REPORT OF THE
COMMITTEE OF INQUIRY ON
Presented to Parliament by the Minister of Agriculture, Fisheries and Food
By Command of her Majesty
HER MAJESTY’S STATIONERY OFFICE
15s od. Net
COMMITTEE OF INQUIRY ON
MINUTE OF APPOINTMENT
I hereby appoint
The Duke of Northumberland, K.G.,T.D., J.P.
A. Cripps, Esq., D.S.O., T.D., Q.C.
Professor D. G. Evans, D.Sc., Ph.D., F.C. Path., F.R.S.
C.H. Plumb, Esq.
Sir Edward Thompson, M.B.E., T.D.
Professor D. Walker, M.A.
Professor Sir William L. Weipers, B.Sc., F.R.C.V.S., D.V.S.M.,
to be a Committee to review the policy and arrangements for dealing with foot-and-mouth disease in Great Britain and to make recommendations.
I further appoint the Duke of Northumberland to be Chairman of the Committee and Mr. J.N. Jotchman to be Secretary, and Mrs. M.D. White to be Assistant Secretary of the Committee.
(Sgd.) FREDERICK PEART
Minister of Agriculture, Fisheries and Food.
28th February, 1968
In addition to the above I hereby appoint
E.L. Thomas, Esq., L.L.B., J.P.
to be an additional member of the Committee.
(Sgd.) CLEDWYN HUGHES
Minister of Agriculture, Fisheries and Food.
22nd April, 1968.
PART 1 OF THE REPORT OF THE COMMITTEE OF
INQUIRY ON FOOT-AND-MOUTH DISEASE
To the Rt. Hon. CLEDWYN HUGHES, M.P.
Minister of Agriculture, Fisheries and Food.
We were appointed on 28th February, 1968:-
“to review the policy and arrangements for dealing with foot-and-mouth disease in Great Britain and to make recommendations”.
We now have the honour to submit Part I of our Report.
We have given priority to consideration of the ways by which the risk of the introduction of foot-and-mouth disease virus into Great Britain, and the risk of future epidemics, might be reduced. Our major task has therefore been to accumulate and evaluate the available scientific evidence and to weigh up the advantages and disadvantages of various possible policies. We have held 29 meetings in this country and have visited Denmark, France, the Federal Republic of Germany, the Netherlands, Argentina, Brazil and Uruguay. The objects of these visits were to hold general discussions on foot-and-mouth disease and to familiarize ourselves with control programmes and the disease situation in these countries. We also visited the Centro Pan-Americano de Febre Aftosa in Rio de Janeiro and we met officials of the United States De-partment of Agriculture in Washington and at the Plum Island Animal Disease Laboratory, Long Island, New York. We received evidence from the Food and Agriculture Organisation of the United Nations and from the Office International des Epizooties. Many countries helped us by supplying infor-mation which we had requested. A large number of organisations and individuals in this country submitted written evidence, and with some of these we have discussed their memoranda. A list of those persons and bodies from whom we have received evidence is in Appendix I.
We wish to thank all our witnesses in this country for the efforts they made on our behalf. Also we are greatly indebted to all those who played a part in the arrangements for our visits to Europe and to North and South America. We deeply appreciate the kindness and courtesy with which we were received, and the frank and full assistance given to us in the conduct of our inquiries.
We interpret our terms of reference as demanding the fullest possible infor-mation we can provide about foot-and-mouth disease and its control and that it is not for us to attempt to express judgments on the social, political and commercial implications of the policy we recommend.
Part I of our Report gives general information about foot-and-mouth disease and deals with measures designed to reduce the incidence of primary outbreaks and the risks of such outbreaks giving rise to epidemics. There remain matters of detailed arrangements if outbreaks occur, including compensation and valuation, which will be the subject of our recommendations in Part II; on these matters we shall be taking further evidence.
A summary of our recommendations is given in Chapter VIII. Anthony Cripps, Q.C. does not wholly agree with all these recommendations. The extent of his disagreement is covered by a Dissenting Note containing his recommendations.
Note: The estimated cost of the Committee’s inquiries to 31st March 1969, including the Cost of producing Part 1 of the Report, is £13,653 19s. Od. of which £1453 19s. Od. represents the estimated cost of printing and publication.
PART 1 OF THE REPORT OF THE COMMITTEE OF
INQUIRY ON FOOT-MOUTH-DISEASE
1 – 2
FOOT-AND-MOUTH DISEASE AND ITS EPIDEMIOLOGY
(a) The Disease
3 - 8
9 – 45
46 – 54
FOOT-AND-MOUTH DISEASE IN GREAT BRITIAN
55 – 56
57 – 63
64 – 71
72 – 82
83 – 96
PREVENTION AND CONTROL OF FOOT-AND-MOUTH DISEASE
(b) In Great Britain
DISCUSSION OF FUTURE POLICIES FOR GREAT BRITAIN
(a) Import Policy
(b) Slaughter Policy
Maps Relating to Cattle Density-
1. Foot-and-Mouth disease is one of the most infectious of all animal diseases. It was first recorded in Great Britain in 1839 and measures for its control were the subject of legislation before the end of the nineteenth century. On three occasions in the past fifty years Committees have been appointed to investigate the cause of outbreaks in Great Britain and to make recommendations on policy, prevention and control arrangements.*
2. The present Committee was appointed following the 1967/1968 epidemic. Our Report, which we are presenting in two parts, will describe the developments that have taken place since the Report of the Departmental Committee on Foot-and-Mouth Disease 1952-54 (the Gowers Committee Report). Part I deals with measures designed to reduce the incidence of primary outbreaks of Foot-and-Mouth Disease in Great Britain and the risks of such outbreaks giving rise to epidemics. Part II will deal with such matters as organization, administration, procedures relating to slaughter and disposal of carcases, sanitary controls, compensation and valuation. In these matters the Ministry of Agriculture, Fisheries and Food (referred to subsequently as the Ministry of Agriculture) have the benefit of long experience, and their record over the years has been one of the considerable achievement. We therefore think it would be wrong to delay the recommendations in part I of our Report until the completion of Part II which will include a review of the detailed control arrangements and ancillary matters. Inevitably there will be some overlap between the two parts.
*(i) Report of the Departmental Committee on Foot-and-Mouth Disease, 1922. (Chairman, Captain the Right Hon. E.G. Pretyman, M.P.) (Cmd. 1784)
(ii) Report of the Departmental Committee appointed to consider the outbreak of foot-and-mouth disease which occurred in 1923-1924. (Chairman, Captain the Right Hon. E.G. Pretyman.) (Cmd. 2350.)
(iii) Report of the Departmental Committee on Foot-and-Mouth Disease 1952-1954. (Chairman, sir Ernest Gowers, G.B.E., K.C.B.) (Cmd. 9214.)
FOOT–AND -MOUTH DISEASE AND ITS
3. We confine ourselves at this point to the main features of foot-and-mouth disease. A detailed description is given in Appendix II. The disease is caused by a virus visible only by using the electron microscope. The virus remains viable under many conditions but it can be destroyed by heat, direct sunlight, acids and alkalis and some disinfectants. There are seven known major virus types-
A : C : O : Asia 1 : SAT. 1 : SAT. 2 : SAT. 3
Sub-types occur within these seven major types and more than fifty sub-types have so far been identified. The immunological difference between the major types is specific and well defined; thus animals which have recovered from infection with one type are for some time immune to that type but they are susceptible to the others. The immunological difference between some sub- types is slight but between others it may be considerable. Foot-and-mouth disease virus may display varying characteristics in relation to infectivity, stability under laboratory tests, severity of the disease, propensity to attack one species of animal rather than another, power of survival outside the animal and ability to stimulate immunity.
4. Cloven-hoofed animals are the natural hosts of foot-and-mouth disease virus. Domestic cattle and pigs are those which most frequently succumb to attack by the virus, sheep rather less frequently and goats still less. Wild cloven-hoofed animals are all apparently susceptible in varying degrees. Hedgehogs have been involved in outbreaks in this country. Man has on very rare occasions been infected; one definite case occurred in Northumberland in 1966. It is unlikely, however, that infection in man plays a part in the spread of the disease. Experimental work has indicated that rats may carry the virus in their gut for long periods following ingestion of infected material and are therefore a potential risk but records do not permit us to conclude whether they can be naturally infected. Laboratory animals such as guinea-pigs may be infected experimentally but they do not develop the disease naturally.
5. Animals are infected with foot-and-mouth disease virus by direct contact with an infected animal. They may also contract the disease indirectly through contact with material contaminated by the virus, for example contaminated feedingstuffs or air.
6. The incubation period after infection varies. It is usually three to eight days but it can be shorter or it may extend to fourteen days or perhaps more. In typical cases the disease is readily diagnosed. In cattle, for example, in the early stages food is refused and lameness follows; salivation, which may be profuse or slight, occurs and is associated with smacking of the tongue and grinding of the teeth. Vesicles (blisters), which are usually ruptured, appear on any part of the mucous membrance of the mouth and occasionally on the udder. The bulb of the heels and the interdigital spaces are commonly affected. In
young calves, however, the characteristic clinical appearances and the post-mortem changes may be absent. In other species there is some variation in the clinical signs of the disease and in the distribution of lesions (see Appendix II).
7. Foot-and-mouth disease varies in its virulence depending on the species of animal affected and on the strain of virus responsible for the outbreak; it can range from a mild form, which may be difficult to diagnose clinically, to one of high severity. In general the death rate from foot-and- mouth disease in adult animals is not high. In Europe, for example, before the introduction of the slaughter policy, the death rate in cattle was estimated to be between one and three per cent. The majority of animals in an infected herd make a gradual recovery after three or four weeks, but in a dairy herd an economic production level is seldom reached during the current lactation, and permanent damage may result, leading to the necessity for heavy culling. The death rate may be higher in young calves and pigs, and in ewes and lambs during the lambing season.
8.Foot-and-mouth disease virus may be present in all parts of the body; it is highly concentrated in the fluid of the vesicles and it is secreted or excreted in the milk, saliva, urine and faeces. All secretions and excretions may contain some virus before the animal has shown signs of the disease and virus may be present in these after the peak of development of lesions. Animals may become carriers and harbour the virus for several months after recovery (see paragraphs 42-45).
9. The incidence of foot-and-mouth disease varies in different parts of the world (see Chapter III). In some parts it is completely absent, as in Australia, Canada, Ireland, New Zealand and the U.S.A.; in others it is present in endemic form as in some parts of South America; in other parts it occurs only sporadically as in Great Britain (see Chapter IV).
Endemic, epidemic and sporadic disease
10. In countries where the disease is endemic, foot-and-mouth disease virus, causing clinical or sub-clinical infection, is continuously present in some animals. Thus the virus does not need to be introduced into these countries to cause an outbreak. Considerable resistance to infection may be shown by certain indigenous species and the presence of the disease may not always be obvious. This is especially true of sheep and also of wild cloven-hoofed animals. Periodically there is an upsurge of the disease, particularly when the susceptible population of young animals reaches a high proportion. This could result in an epidemic with widely-spread outbreaks. At this stage the disease may become more virulent, resulting in a higher death rate. With the spread of the epidemic many of the animals in the country become exposed to the disease and this is followed by the development of immunity; a period of quiescence follows although pockets of disease still remain. The disease may flare up again with an increase in the number of young, susceptible animals or when an outbreak due to a different type of foot-and-mouth disease virus occurs.
11.Sporadic disease occurs in countries which have periods free of the disease; it appears when foot-and-mouth disease virus is introduced from abroad. Countries which have a completely susceptible animal population, as well as those which practice vaccination, may suffer from sporadic outbreaks. Successful control eliminates the disease and a period then follows when the country is completely free from the virus, but where control measures are not successful, a sporadic outbreak may develop into one of epidemic proportions.
Factors involved in the introduction and spread of the disease
12. Foot-and-mouth disease presents serious problems because of the highly infectious nature of the virus and its ability to survive outside the animal host for long periods. Many factors may contribute to the introduction and spread of the disease and these are discussed in the following paragraphs.
(i) Imported animals
13. The disease risks associated with the importation of live animals have long been recognised. Most countries, including Great Britain, control imports of livestock from abroad.
(ii) Imported fresh, chilled and frozen meat and offal
14. Shortly after a healthy animal is slaughtered an acidity develops in the muscles, giving rise to rigor mortis. This reaction can destroy foot-and-mouth disease virus present in the muscle. Acid changes do not take place in any other part of the carcase and thus, if the virus were present, it could survive in bone marrow, lymph nodes, liver and kidney. If freezing or very rapid chilling is carried out immediately after slaughter, the acidity and associated rigor mortis do not develop, and in these circumstances the virus could survive for some months in muscle as well as in the bone marrow, the offal and those other parts already mentioned. Survival of the virus can be prolonged if infected carcases or offal are held in a chilling temperature or a frozen state. Its presence has been demonstrated after about six months in bone marrow stores at 10 C and in frozen offal for at least four to five months. There is no doubt that parts of carcases of animals slaughtered when the virus is present, whether the animals are showing clinical signs or not, can be a dangerous source of infection. However, a study by the Argentine-United States Joint Commission on Foot-and-Mouth Disease has shown that the risk of the virus being present in meat is very much less in vaccinated animals even when they have recently been exposed to infection because the multiplication of virus in such animals is inhibited.
15. Meat, offal and bones from infected carcases may be used in preparing swill for feeding to pigs. Thus swill can constitute a serious risk if it is fed to susceptible animals before it is sterilised. Outbreaks of disease may more often be attributed to the removal of uncooked swill by dogs, cats, birds and vermin to fields, yards and buildings where there are susceptible animals. Kitchen waste stored in uncovered bins, or when carried and spilled from uncovered or unsecured transport, presents another hazard. It is also possible that an outbreak may occur as a result of a farm worker handling swill and then coming into contact with susceptible animals.
16. Bones given to farm dogs may be brought into contact with susceptible animals on any part of the farm. Some bones are disposed of by butchers as
waste which may be taken to a refuse tip. Once there, they constitute a disease risk, particularly on tips in rural areas. Even a controlled tip is not safe since birds can get at the bones before they are covered and can carry small bones and fragments to fields nearby.
17. Although it is known that offal and bones constitute a major risk, we can find only two recorded outbreaks- one in this country and one abroad> attributed to meat where foot-and-mouth disease virus was recovered from commercial carcases associated with an outbreak. Both cases involved pork; in one it was fresh and in the other it was frozen. We do not, however, regard our inability to acquire further evidence of this nature as significant since it is only comparatively recently that virological techniques have been developed that are suitable for the extensive testing that would be necessary to examine a large consignment of imported meat.
(iii) Bones, hooves and horns
18. It is known that foot-and-mouth disease virus survives for long periods in bone from infected animals and there is a possible risk of imported bones, hooves and horns introducing the disease. Imported manufactured products from these materials – for instance bone meal-could also constitute a risk. There is no indication that any such materials or their products have been responsible for outbreaks of the disease in Great Britain since 1938, that is, in the period for which detailed records are available. This may be because the climatic conditions in the exporting countries, the delays that occur before materials can come into contact with animals, and the manufacturing processes are all conductive toward the destruction of the virus.
19. It has been demonstrated experimentally that foot-and-mouth disease virus can be present in bull semen before the infected animal has shown clinical signs and that infected semen can give rise to the disease in an inseminated cow. Thus semen may be a source of infection to other animals. The practice of storing semen at low temperatures is conducive to survival of the virus. However, the risk of introducing the virus into a country, or of spreading the virus within a country by means of infected semen is not considered great.
(v) Glandular products
20. Biological substances prepared from the glands of infected animals may be contaminated by foot-and-mouth disease virus. The virus could be passed to susceptible animals which were being treated with such substances. In 1938 an outbreak in Great Britain was traced to a contaminated imported glandular products used in the treatment of a cow but there have been no recorded cases since then in this country.
(vi) Hay, straw and other vegetable matter
21. Hay and straw are recognised as potentially dangerous materials. Foot-and-mouth disease virus has been shown experimentally to survive on hay for at least 15 weeks, on bran for 20 weeks, and on straw for 4 weeks. Outbreaks of disease in Switzerland have been ascribed to contaminated vegetable matter; there was a remote possibility that an outbreak in Great Britain in 1951 was due to imported bulbs with which cattle might have had contact.
22. The second Pretyman Committee Report (Cmd. 2350) attributed an outbreak to swill which contained parings from imported vegetables. The Gowers Committee found no evidence of this in the period 1938-1953 and outbreaks have not been so attributed subsequently. There was general agreement among our expert witnesses that the risk of introducing the virus into Great Britain with imported vegetable matter is insignificant.
23. Foot-and-mouth disease virus has been shown to survive for long periods on raw and cured hides. The experience in this country suggests that hides are not a hazard since no origins for primary outbreaks have been attributed to them in the period since 1954. The time taken to transport hides to this country and the urban siting of factories probably minimize the risks. The Nene Valley in Northamptonshirea main leather processing areahas had a very low incidence of foot-and-mouth disease over the past thirty years.
(viii) Passenger traffic
24. Spread of foot-and-mouth disease from a primary outbreak has on a number of occasions been attributed to the movement of people who have been in contact with infection, and this will be dealt with fully in Part II of our Report. We also found widespread recognition of the hazard of introducing the disease through foreign travel and by visitors from overseas. With modern fast travel by land, sea or air and the growing mobility of populations this risk is increasing (see also paragraph 140). The foot-and-mouth disease virus can be carried by people on their skin, clothing, shoes and luggage. Experiments have shown that the virus can survive on clothing for periods of from eighty to a hundred days. Tourists in rural areas, farmers and livestock buyers from foreign countries are among those who might inadvertently carry the virus. There have been two incidents in the past where the introduction of foot-and-mouth disease was attributed to the movement of persons between countries. One occurred in 1937 when workers were presumed to have carried the disease to Yugoslavia from France. The second was in Canada in 1952 when the virus was presumed to have been carried to that country from Europe with an immigrant’s effects, possibly on his working overalls or in a meat product. We do not consider this risk to be great; a number of countries which remain free of foot-and-mouth disease received many visitors from countries where the disease is prevalent.
(ix) Vehicular traffic
25. Vehicles that have carried infected animals or have been on infected premises can play a part in the spread of foot-and-mouth disease from a primary outbreak. They may also carry infected material from one country to another (see also paragraph 141). The length of time that foot-and-mouth disease virus would remain viable on a vehicle would depend on the nature of the infected material adhering to the vehicle and on many other factors. It has been shown experimentally that the virus can survive at temperatures of 590 -680F for two to three days in blood dried on iron, for at least two weeks on wool and four weeks on cow hair.
26. The possibility that foot-and-mouth disease virus might be transmitted by the wind has been recognized for a long time. The Gowers Committee were able to point out that the virus could be carried through the air for short distances. They also reported that the veterinarians in Scandinavia were convinced that this was the commonest way in which infection reached their countries. Danish experience supported the theory of windborne infection, and there was an absence of other plausible explanations for the manner in which the virus has spread to Scandinavian countries from Germany.
27. Since 1954 there has been further evidence in support of the theory that foot-and-mouth disease virus is transmitted in air currents. Recent evidence from Denmark suggests that the virus can be windborne for up to eighteen miles over the sea and, in exceptional circumstances, over twice that distance. Danish veterinary officials thought that windborne infection, associated with darkness and damp weather, was the most frequent cause of primary outbreaks in Denmark.
28. In Great Britain much work has been done by the Metereological Office and the Ministry of Agriculture to examine the general hypothesis that meteorological conditions could have favoured the spread of the virus from Continental sources on the occasion of past outbreaks of the disease in Great Britain, and to assess the effects of meteorological conditions on secondary spread in this country. An examination by the Meteorological Office of all primary outbreaks since 1937, except the minor ones, has shown that in every case of multiple and simultaneous outbreaks on the south and east coasts, suitable wind tracks could be found leading back to known infected areas in Europe. It was noted that in the area of the outbreaks, rain, which could have precipitated the virus, occurred at the relevant time. An alternative interpretation by the Microbiological Research Establishment was that the outbreaks could be better accounted for by the favourable effects on the viability of the virus of the high relative humidity prevailing at the time.
29. The Meteorological Office also examined the effect of meteorological conditions on secondary outbreaks of the disease. This was done in five areas: Cheshire (1952); Shropshire (1961); Northumberland (1966); Hampshire (1967); and Cheshire (1967). (The last of these studies had advanced to the point of examining those outbreaks during the initial stages of the epidemic for which there were very few possible authenticated sources; further work is in progress.) The results of the examination suggested that wind and rain might have played a part in the spread of the disease. In general the examination showed that-
(i) few outbreaks occurred upwind of a known source;
(ii) outbreaks were limited to about 2 1/2 miles downwind in dry weather;
(iii) outbreaks extended further down wind in wet weather and even further in periods of light rain;
(iv) Most outbreaks were downwind of more than one possible source of infection on several occasions during rainy periods;
(v) selecting the most likely sources of infection, the percentages of total outbreaks downwind, in relation to distance, were as follows-
33 per cent within 1 < miles
60 per cent within 3 miles
75 per cent within 6 miles
85 per cent within 12 1/2 miles
90 per cent within 18 1/2 miles
95 per cent within 31 miles
(these percentage did not include the Cheshire 1967 epidemic);
One case might have been associated with airborne spread of the virus at a
distance of 50 miles;
(vi) in all five areas there was a number of secondary outbreaks during the
second week following the primary infection; after dry weather the number
was low and after wet weather it was high;
(vii) in all five areas there was a decline in the number of new outbreaks
during a period of dry weather.
The Meteorological Office concluded that the amount of spread due to meteoro- logical causes could be as high as 95 per cent and was unlikely to be less than 80 per cent. They also concluded that spread did not occur unless favourable wind and rain conditions prevailed.
30. The evidence suggests that viruses contained in airborne particles will travel in a viable form in the air for distances of up to thirty miles or more depending on the particle size, the strength of the wind and other factors. Theory and experience suggest that the relevant range of suitable particle size is from 2 to 10 thousandths of a millimeter (2 to 10 microns). The degree of upward mixing of particles depends on meteorological and topographical factors. Transmission of airborne virus might appears to be a greater threat than by day because of the absence of ultra-violet light. The Microbiological Research Establishment suggested that there may be other influences at work in the survival of foot-and-mouth disease virus about which conclusive answers are not at present available. For example, some viruses are known to survive better in association with large particles rather than small ones. Atmospheric relative humidity is a very important factor; high relative humidity appears to prolong the survival of viruses in aerosols. The salt and protein content of the material in which viruses are conveyed and the extent of atmospheric pollution might exert an influence on survival. Although heavy rain may aid deposition of viruses, experiments suggest that it may clear the atmosphere of noxious substances deleterious to the viruses and so prolong their survival.
31. The release of foot-and-mouth disease virus into the air may be brought about in many ways. Present work at the Animal Virus Research Institute on the presence of the virus in the air of animal houses containing infected animals shows that the amount of excreted virus is fairly uniform, starting before the vesicles appear and continuing thereafter. Movement of infected animals or the disturbance of infected materials could create an aerosol containing the virus. Animals either housed or at pasture can be infected by inhalation of airborne virus. It has been suggested that the virus may be drawn up into the air and carried to other sites in thermal air currents generated when infected carcases are burned. In this case the virus source might not be confined to the carcases; contaminated dust particles from the ground surrounding the pyre might also be drawn up into the air and carried away by the wind. During the 1967/1968 epidemic in the west Midlands large volumes of air were sampled at points 100 and 300 yards downwind from fires used to destroy
THE FOLLOWING SIX COLOUR PHOTOGRAPHS
SHOW TYPICAL CLINICAL SIGNS PRESENT IN
ANIMALS AFFECTED WITH FOOT-AND-MOUTH
This proves a ruptured blister on the top of a steer’s tongue , and shows the ragged apperance of the broken “ skin ” ; two pieces of “ skin ” have been removed and laid on the animal’s upper lip. There is extensive seperation of the “ skin ” from the tissue beneath and the typical raw base of the ruptured blister is clearly visible.
This pig’s foot shows blisters as blanched areas at the junction of horn and skin on the heels of the main difits and extending some distance up the back of the accessory digits. The blister on the left main digit has ruptured and lost some of its skin at its outer edge to reveal the raw base. On the left accessory digit the skin has been lost in two places following rupture of the blister.
This shows blisters on the snout and tongue of a pig. There is an unruptured blister on the right side of the snout. At the front of the tongue there is a ruptured blister showing the raw base with the area of blanched and separated “ skin ” at its edges; further back there is a smaller unruptured blister with its blanched “ skin ” .
carcases on two farms. No virus was isolated from the samples but it was thought that the efficiency of the technique employed might not have been high enough to give significant results.
32. Airborne particles can be deposited from the atmosphere by gravity, by downward diffusion of air, by impaction on a solid object or in a falling rain- drop. Large particles (greater than 10 microns) will be deposited close to the source of infection. Virus deposited on pasture or fodder can cause infection when ingested. Smaller particles, on the other hand, will travel in an aerosol and be little affected by gravity or rainfall (other than very heavy rainfall). The probability of infection by inhalation will depend on the concentration of virus-containing particles in the air. It will also depend on the viability of the virus which will be influenced by a number of factors, the most important probably being relative humidity.
33. It has been suggested that animals at free range are exposed to a greater risk from windborne foot-and-mouth disease virus than animals that are housed. On the other hand if buildings are close to a source of infection they may act as a trap for windborne virus, and animals inside may then be at a greater risk than when they are outside.
34. It is possible that birds are responsible for the introduction of foot-and-mouth disease into countries and for its subsequent spread. It is known that the foot-and-mouth disease virus can be conveyed on the feet or feathers of birds and can be excreted by them after ingestion of material contaminated with the virus, but there is no evidence that birds can become infected with the virus. The Gowers Committee pointed out that the virus had been recovered from the feet and feathers of a bird contaminated experimentally as long as 91 hours after contamination. Also it was reported that starlings given the virus by mouth had excreted it in their faces for a period of 10-26 hours. It is thus probable that birds may spread the virus and so cause secondary outbreaks. They are likely to constitute a greater risk if they are carrion eaters such as crows and seagulls. In the recent past there has been considerable misgiving about attributing primary outbreaks to bird migration and it has been suggested that many of the outbreaks so attributed may have been due to windborne virus. Recent Danish evidence suggests that some of the outbreaks previously presumed to have been associated with bird migration to that country cannot be related to migration patterns.
(xii) Milk and milk products
35. Foot-and-mouth disease virus may be present in milk from infected cows a few days before clinical signs appear and may persist for a long time afterwards; milk containing the virus could therefore leave a farm before disease was even Thus milk presents a major potential hazard in transmission of the disease not only by direct transference but also through the contamination of persons, containers and vehicles (see also paragraph 95).
36. Foot-and-mouth disease virus present in milk can be destroyed by varying combinations of time and temperature; an increase in the acidity associated with souring of milk increases the rate of viral destruction. The pasteurisation process used for the treatment of liquid milk may be inadequate to destroy
the virus completely; the virus may also persist in milk for cheese making and
in skim milk for animal feeding. Thus such products, if infected, could play a part in the spread of the virus (see also paragraph 94 and 95). Recent work has shown that the virus in milk from an infected cow is much more difficult to destroy than virus which has been added to milk in the course of an experi- ment.
(xiii) Domestic and wild animals
37. Domestic and wild animals such as dogs, cats and foxes may act as mechanical carriers of foot-and-mouth disease virus, especially the carrion enters. The extent of the risk will depend on the habits of the different species. Rats may be an even greater risk in transmitting infection since they may carry the virus in their gut for long periods. Naturally occurring disease in hedgehogs is well authenticated but the disease producers lameness and they do not travel far when infected. On the other hand the hibernation of hedgehogs might be the means of reviving infection after the lapse of a considerable period of item (see Appendix II). Deer may also become infected naturally as well as acting as mechanical carriers, but they have not been associated with any outbreaks in Great Britain in this century. In some countries wild ruminants and wild pigs are important as sources of infection and in spreading the disease.
(xiv) Insects and arthropods
38. It has been shown experimentally that flies and ticks may transmit foot- and-mouth disease virus from infected to susceptible animals. The virus may survive for long periods in ticks and in their excreta.
(xv) Watercourses and effluents
39. The extent to which streams, rivers and effluents act in spreading foot- and-mouth disease virus is unknown but it an survive in water for a time sufficient for it to be conveyed to neighbouring land by a stream. This is a possible means of spread which might be further investigated.
(xvi) Technical developments in agriculture
40. The pattern of the livestock industry in many countries has changed markedly over the last ten years; in Great Britain for example there has been a reduction in the number of dairy units and a rise in the number of dairy cattle. It was suggested that the number of closed herds may have been declining, with the result that herds are less self contained than they used to be. On the other hand there are indications that the number of closed herds may not be altering significantly; the situation is bound to vary from time to time with changing agricultural policy. Any increasing movement of animals, and other practices associated with intensive farming, such as dung and slurry disposal and bulk milk collection, may well be new factors favouring the spread of foot-and-mouth disease.
(xvii) Excretion of the virus by infected animals
41. An important feature of the disease in relation to its spread is the early excretion of the virus from an infected animal before the onset of clinical signs. Excretion for 24 to 48 hours before the appearance of lesions has long been
accepted but experiments carried out at the Animal Virus Research Institute in 1967 indicate that longer periods of viral excretion may occur. The experi- ments were made with the 01 prototype strain of virus, British Field Strain 1860 (BFS. 1860), isolated from the 1967/1968 epidemic. This work showed that the virus was excreted for a maximum of five days in cattle and sheep and ten days in pigs before the onset of clinical signs. (The experiment is discussed in detail in paragraphs 87 to 89). This earlier excretion is not necessarily a feature associated only with the BFS. 1860 strain; it was demonstrated by the application of new techniques which had not been applied previously. It was pointed out by some of our witnesses that as the evidence relating to early excretion of virus based on laboratory findings, it might not necessarily apply to the same extent in field conditions. However we consider that the excretion of virus can be a significant factor in spread for at least three days before the onset of clinical signs in cattle, and probably for a longer period in pigs.
42. A further significant feature of the foot-and-mouth disease virus is the ability to persist in the convalescent animal, or in the immunized animal exposed to infection without the animal showing any clinical signs of disease. Such animals are referred to as “carriers”, and the virus can be isolated from them. There would thus appear to be a theoretical risk of such animals spreading the disease but there is little evidence that this takes place in the field.
43. At the time of the Report of the Gowers Committee the possibility that vaccinated animals might undergo a mild form of the disease and become carrier animals was recognized, although there was little information about the nature and incidence of the so-called ‘masked infection’ that would then occur. The introduction of general vaccination policies in many countries has made it difficult to study the carrier state in the field, and apart from experimental evidence we have been restricted to reviewing classical observations where carriers might have been expected to occur. An Australian incident associated with the export of bulls from the United Kingdom in 1871/1872, which has been quoted as an instance of carrier transmission, has recently been reviewed by Dr. Murray Puller (Veterinary Research Institute, University of Melbourne), and he suggests that other factors may readily have been responsible. In the U.S.A. in 1914/1915, 740 animals that had either been infected or in contact with foot-and-mouth disease in a show yard were, after a period of isolation, placed in contact with young susceptible cattle and pigs. These young animals remained free of the disease even after a protracted exposure. In an extremely severe epidemic in Denmark in 1938/1939 where some 50 per cent of all cattle were infected, there was no sign that recovered animals subsequently played any part in the spread of the disease. There is some evidence, however, from studies carried out in Africa that animals which had recovered from foot-and-mouth disease many months previously may have infected susceptible animals. Other repeated outbreaks attributed to carriers are not sufficiently scientifically documented for reappraisal.
44. Since 1954 further information has been obtained on the carrier state as a result of investigations by several groups of research workers at the Animal Virus Research Institute, on the Continent, at the Centro Pan Americano de Febre Aftosa (Pan American Foot-and-Mouth Disease Center) in Brazil and at
the Plum Island Animal Disease Laboratory of the United States Department of Agriculture. Their findings may be summarised as follows:
(a) both fully susceptible and immunised cattle may become carriers
after experimental infection;
(b) the virus can be shown to be present in carriers in the mouth,
pharynx, oesophagus and the tonsils (the last especially in sheep);
(c) over a period varying from up to a few months to two years after initial infection, the virus can be recovered from the pharynx and
oesophagus by taking samples of mucus with the aid of an Instrument known as a probing;
(d) susceptible animals kept in close contact with proved carrier animals did not develop clinical signs of the disease nor was the virus isolated from them;
(e) there is some evidence that in a small number of cases, the virus may pass from carrier animals to susceptible animals; this is suggested by the presence of foot-and-mouth disease antibody in a few susceptible animals after exposure to carriers and by one of them resisting challenge with foot-and-foot-and-mouth disease virus;
(f) properly inactivated vaccine, when injected into animals, does not of itself give rise to the carrier state.
45. The consensus of opinion among our scientific witnesses was that the danger of carrier animals had been exaggerated and that carriers in a susceptible population did not constitute a significant risk. (See paragraph 124 for more recent Danish experience.) In this context we quote the European Commission for the Control of Foot-and-Mouth Disease* who have stated that “From the material that has been collected and surveyed it would seem that only in exceptional cases are recovered animals able to transmit foot-and-mouth disease and therefore would seem to play a very small role in the epizootiology of the disease’”.
THE WORLD DISTRIBUTION OF
46. The report of the Gowers Committee reviewed the distribution of foot-and-mouth disease during the years 1929 to 1953 both at home and over- seas. Briefly the position abroad was that the disease had never been known in New Zealand; Australia had not had an outbreak since 1872; the U.S.A. had enjoyed freedom for 25 years and Ireland for thirteen years. Canada had experienced only one outbreak, which occurred in 1952. in the greater part of South America, throughout Asia, in most African countries and in most of Europe, the disease was either endemic or sporadic with occasional epidemics.
47. The position in Australia, Canada, Ireland, New Zealand and the U.S.A. has not altered. We do not have complete information on the world distribu- tion of foot-and-mouth disease but a number of countries provided us with information (see Appendix I). Table I shows the number of outbreaks in the countries that made returns to the Office International des Epizooties (O.I.E.) for the year 1967. Table II shows their population of livestock that are susceptible to foot-and-mouth disease.
Outbreaks of Foot-and-Mouth Disease in Foreign Countries in 1967,
reported to O.I.E.
Algeria .. ..
Angola .. ..
Belgium .. ..
Brazil .. ..
Cambodia .. ..
Ceylon* .. ..
D .. ..
De .. ..
East Germany ..
France .. ..
of Germany ..
Greece .. ..
India .. ..
Iran .. ..
Iraq* .. ..
Italy .. ..
Jordan .. ..
Kenya .. ..
Malawi .. ..
Poland .. ..
South Africa ..
Spain .. ..
Sudan .. ..
Syria .. ..
Togo .. ..
Tunisia .. ..
Turkey .. ..
Upper Volta ..
Vietnam .. ..
* Reported cases.
Algeria.. .. .. ..
Angola .. .. .. ..
Argentina .. .. .. ..
Belgium .. .. .. ..
Brazil .. .. .. ..
Cambodia .. .. .. ..
Cameroon .. .. ..
Ceylon .. .. .. ..
Colombia .. .. .. ..
Dahomey .. .. .. ..
Denmark .. .. .. ..
East Germany .. .. ..
France .. .. .. ..
Federal Republic of Germany
Greece .. .. .. ..
Hungary .. .. .. ..
India .. .. .. ..
Iran .. .. .. ..
Iraq .. .. .. ..
Italy .. .. .. ..
Jordan .. .. .. ..
Kenya .. .. .. ..
Lebanon .. .. .. ..
Malawi .. .. .. ..
Mozambique .. .. ..
Netherlands .. .. ..
Poland .. .. .. ..
Portugal .. .. .. ..
Rhodesia .. .. .. ..
South Africa .. .. ..
South West Africa .. ..
Spain .. .. .. ..
Sudan .. .. .. ..
Syria .. .. .. ..
Tanzania .. .. .. ..
Thailand .. .. .. ..
Togo .. .. .. ..
Tunisia .. .. .. ..
Turkey .. .. .. ..
U.S.S.R. .. .. .. ..
U.A.R. (Egypt) .. .. ..
Upper Volta .. .. ..
Uruguay .. .. .. ..
Venezuela .. .. ..
Vietnam .. .. .. ..
Populations of Susceptible Livestock in the Countries listed in Table I
(1967) (million head)
The disease was also present in 1967 in Burundi, the Congolese Republic, Djibouti, Ghana, Israel, Libya, Paraguay, Republic of Niger, Republic of Nigeria and Uganda, but we do not know the total number of outbreaks. The following countries advised O.I.E. that they had been free from the disease in 1967: Albania Czecholovakia Hong Kong Rumania
Austria Ethiopa Lesotho Sweden
Botswana Finland Malaysia Switzerland
Bulgaria Gaboon Morocco Yugoslavia
It was also reported that the disease does not occur in Jamaica, Madagascar and the New Hebrides, and that Japan has not had an outbreak since 1933. Map I shows the distribution of the types of virus throughout the world since 1954. The present situation is briefly discussed in the following paragraphs.
48. Foot-and-mouth disease is endemic in parts of the African Continent. An important contributory factor to the continued presence of foot-and-mouth disease virus in African countries is the presence of wild animals. For instance when the disease occurs in some border regions of Rhodesia it is sometimes associated with migrations of game from Botswana in the west and from Mozambique in the south-east. Outbreaks of the disease which originate in wild animals often appear to have been smouldering there for some time, and indeed strains of the virus have been found which seem to be adapted prefer- entially to particular species of game. The veterinary authorities in some African countries, for example South Africa, have made determined efforts to restrict the spread of the disease by fencing off some of the game areas. Many African countries are now promoting vaccination schemes.
49. Foot-and-mouth disease is endemic in many areas of South America. The Pan American Foot-and-Mouth Disease Center, which operates under the American Health Organisation, advises on control programmes and a number of countries have embarked on systematic vaccination campaigns. Argentina, Brazil and Uruguay have already established extensive vaccination programmes and a number of other countries are developing schemes. We visited Argentina, Brazil and Uruguay and were impressed by the progress that is being made in controlling foot-and-mouth disease in those countries. The disease situation in Argentina is progressively improving. The Province of Santa Cruz and the territory of Tierra del Fuego appear to be free from foot- and-mouth disease, and if outbreaks occur they would be dealt with by the slaughter policy. Plans are in hand for extending this policy to the Provinces of Chubut and Rio Negro, and a buffer zone is maintained between the Rio Negro and the Rio Colorado, in which all cattle, sheep and pigs are vaccinated, to protect the disease-free area to the south. We would expect that the vigorous pursuit of their policies will lead to the gradual isolation and then the extension of disease-free areas in all three countries.
North and Central America
50. The U.S.A. and Canada have been free for many years from foot-and-mouth disease; the last outbreak in Canada was in 1952 and in U.S.A. in 1929- both outbreaks were eradicated by slaughter. Central America has been free the disease for some time. The Pan American Health Organisation controls the entry of all animals, vehicles and travellers entering Panama from the South American Continent, and there is a zone across the Darien peninsula in which there is a restriction on movement of cattle. Most of the large Caribbean islands are free; the last outbreaks were in Curacao in 1961 and in Guadeloupe in 1964.There was a serious outbreaks in Mexico in 1948 which was eradicated
(see paragraph 122); the country has been free of the disease since 1953.
51. Foot-and-mouth disease has never been known in New Zealand. Australia has been free of the disease since 1872.
Asia and the Sub-Continent of Asia
52. In large areas of South-East Asia and the Sub-Continent of Asia foot- and-mouth disease is endemic. We have no precise information about the disease in China but Japan has been free since 1933. In the Middle East sporadic disease occurs from time to time and the disease is endemic in certain areas.
U.S.S.R., Central and South-East Europe
53. Foot-and-mouth disease is reported to be sporadic in European U.S.S.R. but endemic in the cattle raising areas of Central Asia. It is said to be present in wild animals in these areas and in adjoining countries. Outbreaks occur from time to time in the Balkans and in Central Europe and may at times give rise to epidemics. The disease appeared in Rumania in 1959 and spread to the neighbouring countries of Bulgaria, Yugoslavia and Hungary. About the same time outbreaks occurred in Poland and Finland. By 1960 Rumania and Bulgaria, and by 1961 Yugoslavia, were once again free of the disease but sporadic outbreaks have occurred since. By agreement with Czechoslovakia, Poland and Rumania, the U.S.S.R. maintains buffer zones of vaccinated along its frontiers with these countries and in some areas zones about nine miles wide are kept free from all susceptible livestock for additional security. Bulgaria continues to vaccinate in its border area adjoining Turkey as part of the campaign to protect south-eastern Europe against types of virus from which Europe is generally free. (In paragraph 121 we describe the measures that were taken from 1962 onwards to fight the spread into Europe of South African type SAT. 1 virus and of type A22 virus which spread through Turkey and the Anatolian Peninsula as far as Greece.)
54. Table III gives the incidence of foot-and-mouth disease from 1954 to 1968 in the European countries nearest to Great Britain. Outbreaks in Great Britain are also shown, for the purpose of comparison. Luxembourg Northern Ireland, Norway and the Republic of Ireland have had long periods of complete freedom from the disease. In the remaining countries mentioned in the table, outbreaks of the disease have occurred regularly in most years, and during some periods a number of countries such as France, the Federal Republic of Germany, Italy, Portugal and Spain have suffered heavy attacks. Among more distant countries not included in the table, Finland has been free since 1959 and Sweden since 1966. The disease has never been introduced into Vaccination has been used to control outbreaks of the disease in some European countries since about 1939, and by 1960 countries such as France and the Netherlands had developed and were applying general pro- phylactic vaccination programmes. These programmes, together with the slaughter policy, have greatly reduced the general level of infection in Western Europe over the last few years. This is especially evident in France where there was a steep fall in the number of the outbreaks after 1961.
Incidence of Foot-and-Mouth Disease in some European Countries, 1954-1968
Belgium .. ..
Denmark .. ..
Federal Republic of
Germany .. ..
France .. ..
Italy .. .. ..
Luxembourg .. ..
Netherlands .. ..
Northern Ireland ..
Norway .. ..
Portugal .. ..
Republic of Ireland ..
Spain .. .. ..
Switzerland .. ..
Great Britain .. ..
Note: The figures above show numbers of outbreaks, with the following exceptions. Source: (1954-1967) Reports of the European Commission for the control of
* = Number of animals affected. Foot-and-Mouth Disease.
† = Villages or municipalities affected (1968) Ministry of Agriculture
‡ = Up to September.
FOOT-AND-MOUTH DISEASE IN GREAT BRITAIN
55. Foot-and-mouth disease is not endemic in Great Britain where the latest returns show a susceptible livestock population of about 44 million. Figures I and II illustrate the prevalence of the disease in the period 1954- 1967 and the relationship of primary outbreaks to secondary spread. * There was a period of complete freedom from the disease from June, 1962 to March, 1965 and over the years there have been long intervals between individual outbreaks stemming from each of the three main virus types.
56. The slaughter policy adopted in Great Britain has resulted in an entirely susceptible livestock population and if foot-and-mouth disease virus were continually present in the country more frequent outbreaks would undoubtedly have occurred. Further, there is an annual importation of about 400,000 Irish store cattle and a relatively small number of store sheep which are widely distributed to farms in Great Britain, and the fact that these susceptible animals do not develop the disease is also an indication that it is not endemic in Great Britain.
57. In reporting on the situation at home, the Gowers Committee was unable to point to any single year in the period from 1929 to 1953, over which their review extended, in which the country had been completely free from foot-and-mouth disease; the last period of complete freedom had been in 1917. occurred in each of the years from 1954 to 1960, and in four of these years reached fairly high levels. The high incidence of disease persisted into 1961 with 101 outbreaks from 1st January to 15th April of that year. By contrast, the years from late a1961 to mid-1966 saw record low level of disease. There was only one outbreak in the last half of 1961, and five in the first half of 1962 of which two were primaries; and thereafter the country remained completely free from the disease until April, 1965 when an isolated outbreak occurred in Kent. This was followed by fourteen months freedom until July, 1966, when the disease broke out in Northumberland; the virus type was 01. The affected district was heavily stocked with grazing cattle, and 250,000 breeding ewes and lambs were on open grazings nearby. If the disease had reached the open grazings a very large number of sheep might have become infected and the disease might have spread into Scotland and southwards along the Pennines. In the event, a large Infected Area † was declared and in several instances stock were slaughtered on farms adjoining the infected premises in order to establish a buffer zone devoid of stock to protect the free-range grazings. disease was successfully confined to two fairly small districts within the
* A primary outbreak is one that cannot be linked with any known source of infection in livestock in Great Britain and is therefore attributed to the virus having been introduced from abroad. Secondary outbreaks are those which arise from a spread of infection from primary outbreaks or previous secondaries.
† An Infected Area is an area defined by Statutory Order in which movements of animals and the holding of markets are prohibited except under license.
Infected Area and did not spread to other counties. In all, the disease was confirmed on 32 farms; 5,753 cattle, 38,448 sheep and 714 pigs were slaughtered.
58. Towards the end of September, 1966 there was a primary outbreak in Sussex, with one secondary, involving type A22 virus which was the virus type responsible for the epidemics in the Near East at that time. No connexion could be traced, however, between the Sussex outbreak and any external source.
59. On 8th January 1967 a primary outbreak in pigs in Hampshire (type 01 virus) resulted in 28 secondary outbreaks over a period of four weeks. Five of these were linked with a local abattoir where pigs from infected premises had been sent for slaughter. Between 4th and 7th September four other outbreaks were confirmed at Stratford-on-Avon in Warwickshire (see paragraph 62) and again the virus type was 01.
60. The general improvement in the years 1961-1966 coincided with a period of marked reduction in the level of infection in Belgium and France. But it also coincided with an unusually high incidence of disease in Netherlands and the Federal Republic of Germany (see Table III).
61. Notwithstanding the general improvement form 1961-1966 there were episodes in Great Britain in the period under review, which presented alarming characteristics. An outbreak in cattle in Forest of Dean, Gloucestershire in 1956 involved common grazings and although free-ranging stock were at once brought into enclosures, the movements of sheep and the communal dipping which had already taken place led to widespread infection. In 1957 there was an outbreak in pigs on a farm in Caernarvonshire where the disease had been present for several days before it was confirmed. Hundreds of owners, many of whom kept small numbers of pigs, had their stock slaughtered because of the risk of contact with the disease. The infected Area embraced mountainous, unfenced country, including Snowdonia, but fortunately the disease did not reach the mountain sheep. There was a unique outbreak in mid January, 1960 on a farm in Surrey adjoining the Animal Virus Research Institute at Pirbright. The virus was of a South African type, which had apparently escaped through the Institute’s ventilation system to fields surrounding the inner compound; it was thought to have been spread to the farm by birds or by other wild life. There was no secondary spread from this one primary outbreak , which occurred on a farm in Northumberland, was not detected until the infected animals had reached a slaughter-house in Durham. A large number of subsequent outbreaks was attributed to movements of cattle through markets and slaughter-houses, and the disease spread to Scotland for the first time in seven years.
62. In the period 1954-1967, the disease was diagnosed in 86 per cent of all outbreaks when lesions in the animals were estimated to be less than two days old, and in 71 per cent when lesions were estimated to be less than a day old. From 1959 to October, 1967, however, there were 17 outbreaks where the animals had lesions over seven days old before the disease was confirmed. Of these 17, five had not been reported and were found when the Ministry of Agriculture was carrying out routine investigations during outbreaks; two were discovered in slaughter-houses and in four the lesions were atypical. During this period there were two convictions for failure to report suspected cases. One was in
Relationship of Primary Outbreaks of Foot-and-Mouth
Disease to Secondary spread in Great Britain,
1954 to October, 1967
Gloucestershire in March, 1960 and the other was in Warwickshire following an outbreak of disease on 4th September, 1967 where the animals were found to have been infected for seven to ten days when the outbreak was confirmed.
63. A recent example of atypical lesions occurred in the initial outbreak in Northumberland in 1966. At the first investigation the clinical diagnosis presented difficulty and the laboratory tests proved negative. Restrictions were removed but these were re-imposed when the disease was confirmed on clinical grounds two days later on the original farm and on two nearby premises.
64. In October, 1967 the first outbreak of foot-and-mouth disease in what was to become the worst recorded epidemic in this century, was reported at Bryn Farm, Nantmawr, Oswestry, Shropshire. The epidemic, which lasted until 4th June, 1968, caused 2,364 outbreaks, on 2,346 farms, 18 of which were infected on two occasions. The epidemic resulted in the slaughter of 433,987 animals, including 211,825 cattle, 113,766 pigs, 108,345 sheep and 51 goats.
65. The sequence of events relating to the outbreak on Bryn Farm was as follows. On Saturday, 21st October the owner noticed that one sow was lame; one day later a second sow was seen to be lame. Both animals were removed from the yard and housed. By Wednesday, 25th October a third sow and eleven store pigs were ailing and at this stage veterinary advice was sought. Before the veterinary inspector arrived at the farm, two cows had been sent in the morning to Oswestry market. The inspector diagnosed foot-and-mouth disease immediately on examining the pigs and found that seventeen were infected. ( It is probable that the outbreak on this farm had started in the sows that had been seen to be lame on 21st and 22nd October and that they had transmitted the disease to the remaining pigs). As soon as the disease was diagnosed, the usual restrictions were applied to the farm and to the market. There were 1,963 animals still in Oswestry market and these were detained in the sale yard. One of the two cows that had been sent to the market from Bryn Farm had already left the market by vehicle but was stopped by the police and returned to the farm; the other cow was returned to the farm direct from the market. These two animals were included in a veterinary examination of all the stock at Bryn Farm on the morning of Thursday, 26th October by which time it was found that 28 pigs were infected although no cattle showed any clinical signs. The entire stock on the farm, consisting of 71 Cattle, 67 pigs and 47 sheep, were slaughtered and buried that day.
66. It was decided that none of the stock that had passed through, or were detained in, Oswestry market should be slaughtered as the two cows which had been sent there from Bryn Farm had not shown any signs of being infected with food-and–mouth disease. The decision was therefore taken to clear the market of the detained animals which were inspected and licensed to move either to slaughter-houses or to various farms in the Infected Area. This decision caused much concern among farmers since it was feared that as a result of this dispersal the disease would spread. Nevertheless the market was cleared by the morning of Saturday, 28th October. Many of the animals that had been sent to the market on the Wednesday had been dispersed before movement restrictions were applied, and some had gone as far afield as Banffshire and Devon. These were traced and examined by the veterinary staff of the Ministry of Agriculture. The animals that had been detained and subsequently dispersed were also later re-examined by veterinary inspectors. None of the animals that had been in the market developed foot-and-mouth disease as a result of contact with animals from Bryn Farm.
67. A second outbreak of the disease occurred on Saturday, 28th October and a third was confirmed on the next day; both were in close proximity to Bryn Farm. The situation at this stage did not give cause for anxiety to the Ministry of Agriculture.
68. The position changed dramatically on Monday, 30th October. Nine outbreaks were confirmed on that day and although six of them were close to the original outbreaks, one was at Ruabon, Denbighshire twelve miles distant, another at Darnhall, in Cheshire 35 miles away and another at Carnforth in Lancashire nearly 100 miles away. On Tuesday, 31st October eleven more outbreaks were reported at Cheshire and Shropshire. This concluded the first seven days of the epidemic during which there had been 23 outbreaks.
69. In the next seven days beginning 1st November there were 104 outbreaks, in the following seven days 222, and from then on there was a steady increase in the number of outbreaks until the peak was reached towards the end of November when 490 occurred within the seven days beginning 22nd November. Thereafter there was a steady, but slow, decline in the number of outbreaks until towards the end of February, 1968. From then on there were relatively few outbreaks but they continued through March, April and May until 4th June, 1968 when the last outbreak occurred.
70. During the later phase of the epidemic, from mid-February onwards, eighteen outbreaks occurred on previously infected farms, which had been allowed to restock. Of these, seventeen were on farms situated in heavily infected areas of the north-west Midlands. After investigating the eighteen outbreaks the Ministry of Agriculture considered that twelve of them were due to a recrudescence of the disease, possibly as a result of infected material remaining on the farm ;after the original outbreak, and that the remaining six were due to spread of infection from neighboring farms. The recrudescent outbreaks occurred in Cheshire (4), Staffordshire (2),Shropshire (2), Flintshire (2), Denbigshire (1) and Worestershire (1)
71. The general pattern of the epidemic is illustrated in Figure III and Map II which show that the north-west Midlands and North Wales were the most heavily infected areas.
72. The Report of the Ministry of Agriculture’s Chief Veterinary Officer on the origin of the 1967/1968 foot-and-mouth disease epidemic (Cmnd. 3560) was submitted to us as evidence. Its text is reproduced in Appendix III. The Chief Veterinary Officer reported that the initial outbreak of the disease was in pigs at Bryn Farm on 25th October, 1967. He considered all the known possible means by which foot-and-mouth disease virus could have been brought to the farm and he dismissed the possibility of any connection between the outbreak at Bryn Farm and the last previous outbreak in Warwickshire in September, 1967. The chief Veterinary Officer concluded that the most likely source of infection was frozen Argentine lamb, which might have been supplied to the farm during October. A consignment of 770 frozen lamp carcases from Establishment 1408 in Argentina had been widely distributed in Cheshire and Shropshire between August and November, following importation on 25th August. The Chief Veterinary Officer drew attention to the large number of outbreaks which were reported almost simultaneously over a wide area; he
suggested that there might have been a number of primary outbreaks at about the same time and that there was a possible link with the imported frozen lamb carcases.
73. The Report referred to other consignments of lamb from Establishment 1408 which had been traced to Nottinghamshire, the west Midlands, London, the area around Portsmouth and Southampton, Bristol and South Wales and Newcastle where no outbreaks occurred. It also pointed out that later on in the epidemic new isolated foci of disease arose in widely dispersed locations. Some of the farms involved could be linked with frozen lamb from Establishment 1408 but there was no clear evidence that the lamb was responsible for any of these outbreaks. Samples for virus isolation were not taken from lamb carcases from Establishment 1408 as the consignment had already been distri-buted, but samples were taken from other lamb carcases from Argentina and no virus was isolated. The Chief Veterinary Officer’s summing up was that he had been unable to discover any possible source of the infection except frozen Argentine lamb which, he concluded, was the cause of the initial outbreak on Bryn Farm and some of the subsequent outbreaks (see Appendix III).
74. The Chief Veterinary Officer’s Report was written on 7th February, 1968, before a full investigation of all the outbreaks had been completed. The Ministry of Agriculture gave evidence based on their subsequent findings which they claimed did not detract from those of the Report in any way but rather served to support them. Their full investigation showed that in 24 outbreaks throughout the entire epidemic there was a possible link with lamb from Establishment 1408 but that in a number of these the only evidence was that the lamb had been distributed in the district. In addition sixteen other out-breaks had tenuous links with meat of South American origin―some of which could possibly have come from Establishment 1408.
75. Map III shows the primary distribution of lamb from Establishment 1408 in Great Britain during the period July to December, 1967. We were told that a substantial quantity was redistributed in the rural area north and north-west of Oswestry. Map IV shows the location of retailers in the north-west Midlands receiving Argentine frozen lamb in the months August to November, 1967, both from Establishment 1408 and other establishments, and also the extent of the epidemic up to the end of November. It was clear to the Committee that the lamb had been distributed through normal commercial channels and no blame can be attached to any of the distributors.
76. The general pattern of bulk distribution of South American meat in Great Britain in the period July to December 1967 was also investigated by the Ministry of Agriculture. Beef, and to some extent Offal, were widely distributed in Great Britain though very small amounts went to Scotland, the south-west of England and East Anglia. Lamb and mutton were distributed to the major cities and considerable quantities were sent to centres within or bordering on the main areas of infection. However, from Dover to Bourne-mouth and north to Salisbury and London, over a thousand butchers’ shops were receiving Argentine beef, mutton, lamb and offal during that period and no outbreaks occurred in these areas of England.
77. In view of the large number of outbreaks of the disease which rapidly occurred in the early period of the epidemic, for example 61 in the first ten days, the question was put to many of our expert witnesses as to whether they
Primary distribution of lamb from Establishment 1408 in Argentina
For the period July to December 1967
considered the epidemic was a result of one primary outbreak or a number of primary outbreaks occurring almost simultaneously. Experts from the Ministry of Agriculture considered that the weight of infection at Bryn Farm was hardly sufficient to account for the explosion of outbreaks that followed and pointed out that the two cows that had been sent from the farm to Oswestry market had shown no clinical signs of the disease, nor had they transmitted infection to other cattle in the market. The Ministry’s witnesses were inclined to the opinion that there had been a series of multiple primary outbreaks over a short period and that the one at Bryn Farm happened to be the first to become apparent. They supplied Map V on which are plotted the outbreaks in the Cheshire Plain during the period 25th October to 14th November, 1967 and on which are indicated 19 outbreaks that might have been primaries resulting from imported meat. The basis of some of these suggested primary outbreaks was no stronger than that imported frozen lamb, including some from Establishment 1408, had been distributed in the district.
78. The question of whether the characteristics of the strain of foot-and-mouth disease virus isolated from the initial outbreak would throw any light on the origin of the epidemic was put to the Animal Virus Research Institute. They informed us that the strain isolated from this outbreak belonged to sub-type 01 as did other strains isolated throughout the epidemic. One of these, isolated from an outbreak at Wrexham on 1st November, 1967, was designated British Field Strain (BFS) 1860 and used as the prototype for the epidemic. As sub-type 01 is widely distributed throughout Europe, South America and other countries it was impossible to draw any firm conclusions about the origin of the epidemic on the basis of typing only. The Institute thought that it was possible that the virus had been introduced into this country in South American meat but they did not dismiss the possibility that it might have come from Europe. It was pointed out that there was a similarity between the BFS. 1860 strain and the 01 Lausanne strain which had been common in Europe. The experts could not explain how the virus might have been introduced into this country from Europe but they reminded us that travellers could have carried the virus, although this was a remote possibility. In addition they drew our attention to the Warwickshire outbreak in September, 1967 and told us that the 01 strain isolated at that time was indistinguishable in its stability in the laboratory from strain BFS. 1860 of the 1967/1968 epidemic.
79. Early in the outbreak the Animal Virus Research Institute made some tests of antibody levels for foot-and-mouth disease in sera from sheep sent for slaughter from farms around the original area of infection; the results were negative. On all the evidence available the possibility was dismissed that sub-clinical infection in sheep had preceded the initial outbreak at Bryn Farm. In January, 1968, after the peak of infection had passed, further tests were made in an attempt to detect whether there had been any inapparent infection among sheep on farms contiguous to those where foot-and-mouth disease had occurred. Samples of sera from 59 sheep on 23 farms in the Oswestry area were tested. In the opinion of the Institute the antibody levels to foot-and-mouth disease virus were sufficiently high in three of the serum samples, taken from two farms, to indicate that infection had occurred; these sheep, however, had not passed the infection on to the rest of the flock. The possibility of infection being present
and of being a danger to other stock was regarded as negligible so no further action was taken by the Ministry of Agriculture. We questioned our witnesses on the significance of these observations with particular care. The Animal Virus Research Institute and the Ministry of Agriculture assured us that these incidents were exceptional and did not contribute to the spread of infection during the epidemic. Members of the Ministry’s staff agreed that the results of the serological tests might well have been caused by foot-and-mouth disease virus. However, they were of the opinion that the animals had not had clinical foot-and-mouth disease, that they had not passed infection to contacts on the same farm and that they would not spread the disease to other susceptible animals.
80. We conclude that it is impossible to establish without doubt the origin of the 1967/1968 epidemic. However, having considered all the facts we think that there is a basis for a reasonable inference that the most probable source of the epidemic was infected meat from South America. We do not have sufficient evidence to suggest that the infected meat came from any one particular meat exporting country in South America or from any one particular establishment.
81. We cannot completely set aside other likely sources of the epidemic, having regard to the multiplicity of means by which the disease can be trans-mitted. We consider for instance that the epidemic may have had a link with the Warwickshire outbreak of September, 1967 which was also attributed by the Ministry of Agriculture to South American meat. One theory that can be dismissed is that the epidemic might have been started by windborne virus from the Continent. The Meteorological Office studied the meteorological pattern and were unable to find any suitable wind track during the critical period.
82. We also conclude that it is impossible to identify the number of primary outbreaks in the epidemic. It is difficult however, to explain the rapid develop-ment and extension of the epidemic other than by accepting that a number of foci were established more or less simultaneously. Although such foci may have been primary outbreaks, arising from the distribution of imported meat, there is nevertheless the possibility that some of them may have been secondary outbreaks. For example some of the 28 pigs on Bryn Farm, affected at the time of slaughter, could have been excreting virus for ten days, and two of them for fifteen days, before being slaughtered. However, if this had been so it is surprising that none of the cows on Bryn Farm developed foot-and-mouth disease, and the two sent to market were unlikely to have been in the incubating stage because they did not affect the other animals in the market. Another example of the possibility that a number of foci may have been established early in the epidemic as a result of secondary spread was an outbreak confirmed in Oswestry rural parish on 30th October when seven dairy cows in a herd of 128 were found to have clinical signs of the disease; one of the cows was considered to have lesions that were three days old. Seven other cattle showed clinical signs and all the infected animals together with the animals in immediate contact, had been slaughtered by 31st October. The remaining 77 animals in the dairy here were slaughtered on 1st November and twelve sheep were slaughtered on 2nd November. Such a situation could be conductive to the
dissemination of the virus and the initiation of further multiple outbreaks, thereby contributing to the rapid development of the epidemic in its early phase. Another cause of multiple outbreaks could have been result of disease being present for some time in animals which did not show clinical signs but which were excreting virus; we considered this but found no evidence to support the theory. Neither was there any evidence that the disease had been deliberately concealed.
83. Table IV shows the weekly record of outbreaks divided, for convenience, into five areas. These are:
Area I―NORTH-WEST MIDLANDS Flintshire,
AND NORTH WALES Montgomeryshire,
II―LANCASHIRE & WESTMORELAND
IV―SOUTH-WEST MIDLANDS Monmouthshire,
AND SOUTH WALES Warwickshire and
V―EAST MIDLANDS Leicestershire, Lincolnshire, Northamptonshire and Nottinghamshire.
This table, together with the map of distribution of outbreaks (Map II) and the chart of daily totals (Figure III), all show that by far the largest number of outbreaks (94 per cent) occurred in the north-west Midlands and North Wales (Area I), and we have concentrated out discussion in the following paragraphs mainly on the development of the disease in that area. We have however included some comment on outbreaks in other areas where these appeared to have some epidemiological significance. The Ministry of Agriculture attributed nearly all the secondary outbreaks to local spread which might have been brought about by wind, birds, rodents, other fauna and unknown means. They attributed 51 other outbreaks to the causes shown in Table V.
*Returns of Outbreaks of Foot-and–Mouth Disease throughout the 1967/1968
And North Wales
and South Wales
1967 October 25th .. .. ..
November 1st .. .. ..
November 8th .. .. ..
November 15th .. .. ..
November 22nd .. .. ..
November 29th .. .. ..
December 6th .. .. ..
December 13th .. .. ..
December 20th .. .. ..
December 27th .. .. ..
1968 January 3rd .. .. ..
January 10th .. .. .. ..
January 17th .. .. .. ..
January 24th .. .. .. ..
January 31st .. .. .. ..
February 7th .. .. ..
February 14th .. .. ..
February 21st .. .. ..
February 28th .. .. ..
April 1st .. .. .. ..
May 1st .. .. .. ..
June 1st .. .. .. ..
Grand Total .. .. .. ..
Analysis by the Ministry of Agriculture of Sources of Infection in
outbreaks of Foot-and-Mouth Disease during the 1967/1968 Epidemic
Attributed to Movement of―
Animals .. .. ..
Vehicles .. .. ..
Veterinary Surgeons .. ..
Other persons .. .. ..
Milk products .. .. ..
Hay .. .. .. ..
Recrudescent outbreaks .. .. .. ..
Total .. .. .. ..
(a)―15 milk lorries (8 milk tankers, 7 churn
collection), 2 stock lorries, 1 slurry tank.
(b)―8 skim milk, 1 churn washings.
84. The Ministry of Agriculture’s witnesses thought that compared with previous outbreaks of foot-and-mouth disease in recent years, the 1967/1968 epidemic showed some new features in that the speed and extent of spread were abnormal. There was, however, no evidence from the length of the incubation period of the disease that the infection differed from previous ones. In cattle the period of incubation was from two to five days, in pigs from five to eight days and in sheep (although this was more difficult to determine precisely) from three to seven days. There was evidence that some sheep had exhibited a greater resistance to infection than was expected but such resistance had occurred in outbreaks in the past, and even when severe infections did occur in sheep they did not give rise to much local spread of the disease. Another characteristic of the epidemic was that pigs did not seem to be readily infected; of the 113,766 pigs slaughtered only 327 showed clinical signs of disease.
85. Laboratory evidence obtained by the Animal Virus Research Institute showed that the 01 sub-type strains of virus (BFS. 1860) isolated from the 1967/1968 epidemic had characteristics similar to those of other sub-type 01 strains isolated in previous outbreaks in Great Britain. It has been established that the BFS. 1860 strain is a little more stable under laboratory conditions than other similar strains but it was considered that this factor did not contribute significantly to the nature of the epidemic.
86. During the whole period of the epidemic samples were taken from animals where a primary outbreak was suspected, from a random number of cases in the heavily infected areas, and from clinically doubtful cases for diagnostic purposes. The samples were examined at the Animal Virus Research Institute for isolation of virus and typing, and strains recovered belonged to sub-type 01. The results are shown in Table VI. A more detailed investigation
Isolation of Foot-and-Mouth Disease Virus from
Samples taken during the 1967/1968 Epidemic
Number of samples from
which the virus was
Confirmed cases ..
Doubtful cases ..
Total .. .. ..
was also made of five samples from animals in the areas of Oswestry, Lincolnshire, Nottinghamshire, Warwickshire and Leicestershire between 28th October, 1967 and 19th January, 1968. All the strains of virus isolated from these samples also fell into sub-type 01 and there was no evidence of any change in sub-type during the course of the epidemic.
87. Experiments were also made at the Animal Virus Research Institute to relate the time of excretion of the virus by infected animals to the develop-ment of lesions. Cattle, sheep and pigs were infected by contact with other animals, which had been infected by injecting the virus, and samples for isolation of the virus taken from various sites during the development of the disease. The results of this work are summarised in Table VII.
Isolation of Foot-and-Mouth Disease Virus in
Relation to Development of Lesions
Steers .. ..
Cows .. ..
Sheep .. ..
Pigs .. ..
Number of days
for lesions to develop after
Number of days before
development of lesions
When virus was first
88. In the same experiments determinations were made of the quantity of virus isolated from these sites. The results are shown in Table VIII.
Quantity of Foot-and-Mouth Disease Virus
Isolated at Various Sites in Animals
Maximum number of infectious particles
per sample or per ml. Of milk*
Pharynx .. ..
Milk .. ..
Rectum .. ..
Vagina .. ..
* Number of infectious particles indicated by log scale.
Thus 102 =100, 105=100,000 and so on.
89. It is clear from the results in paragraphs 87 and 88 that considerable quantities of foot-and-mouth disease virus could have been excreted from infected cattle and sheep for as long as five days, and in the case of pigs for as long as ten days, before the appearance of clinical signs. We think, however, that this is not necessarily a unique characteristic of the BFS. 1860 strain because little work has yet been done on strains isolated from previous outbreaks.
90. By the second week of the epidemic, when the disease was becoming widespread, the pattern of spread seemed to be conforming to a well-defined shape. This took the form of a fan from an apex in the hills at Nantmarwr with the western boundary running northwards alongside the mountains towards Wrexham and Chester and the eastern boundary running towards Whitchurch and Crewe. The Cheshire Plain lay within these boundaries. In the third and fourth weeks of the epidemic there was roughly a twofold increase in the number of outbreaks all but 24 of which were in the Cheshire Plain or the immediate surroundings. Map VI illustrates the developing pattern of spread of the disease in the Cheshire Plain during the first three weeks of the epidemic. This area has always had a high concentration of livestock and part of it is the most heavily stocked dairy country in the world. In the conditions of the outbreaks,concentration of livestock in the Cheshire Plain undoubtedly favoured the rapid spread of the disease. The maps at Appendix IV show how cattle densities in Great Britain have increased over the last nine years and how closely the areas of highest density are related to the areas which suffered the highest concentration of outbreaks.
91. There is a continuing tendency in Great Britain for livestock to be kept in large groups; stocking densities are becoming heavier and there is much more communication of all sorts between farms, including the movement of animals. The British Veterinary Association and the Royal College of Veterinary Surgeons thought that in some areas all the livestock should be regarded as an integrated population in relation to the spread of disease. This is particularly
true in dairying areas with a high percentage of small farms and with few
natural breaks such as arable land and woodland between them. In this respect it is interesting to note that in the less densely stocked areas such as Nottinghamshire, Lincolnshire and Northamptonshire there was little or no local spread of the disease. Developments in husbandry, and in the industries supporting agriculture such as those mentioned above, are by no means the only ones which might play a part in the spread of the disease. Other modern practices in relation to livestock, milk marketing, artificial insemination, and transport and deliveries to farms contribute to the risks (see also paragraph 40).
92. The Meteorological Office studied the meteorological factors that might have had a bearing on the pattern of spread of the epidemic and they concluded that wind could have played an important part in spreading infection. They thought it was significant that at the time of the initial outbreak at Nantmawr and for the following nineteen days the prevailing wind was from the south-west and that about 75 per cent of the first 100 outbreaks were lying to the north and north-east of the initial outbreak. They also thought it was significant that rain fell on seventeen of the nineteen days when winds blew consistently from the south-west. We noted that very few outbreaks occurred in the opposite direction, into the wind (see Map VI). This cannot be accounted for over a ten mile range either by a difference in concentration of holdings or of concentrations of livestock. The evidence supports the theory that wind carriage of the virus together with deposition by rain at night may have been responsible for secondary outbreaks particularly during the first month of the epidemic. The range of spread might have been up to thirty miles depending on weather conditions but the longer jumps of infection into Lancashire, Nottinghamshire and Warwickshire were not thought by the Meteorological Office to be associated with windborne spread.
93. The Ministry of Agriculture investigated the possibility that the virus might sometimes have been carried by thermal air currents from sites where infected carcases were burnt. There were three instances in Derbyshire during December, 1967 where outbreaks occurred downwind of infected premises after an interval of from eight to eleven days. In these three outbreaks the carcases had been destroyed by burning, and cremation could have been responsible for the spread of disease. In other outbreaks in Derbyshire where conditions appeared to favour the spread of disease while carcases were burning, there were no subsequent related outbreaks.
94. Another series of outbreaks which occurred during the fourth week of the epidemic was of significance in relation to the spread of disease. At Spetchley in Worcestershire, some forty miles from the nearest outbreak in the north-west Midlands, three outbreaks occurred in pigs, and were then followed by a further 27 outbreaks, all within a radius of three miles. The three original outbreaks were attributed by the Ministry of Agriculture to the feeding of the pigs with skim milk from a dairy where the plant had probably been contaminated by infected milk. In the same week outbreaks occurred in Gloucestershire, at Winchcombe and near Moreton-in-the-Marsh; in both instances pigs were the first animals affected. The source of infection was held to be skim milk from the dairy that had been involved in the Spetchley outbreaks. There was also an outbreak at Wolverhampton which was attributed to skim milk from the same dairy.
95. Although it is generally accepted that infected milk can contaminate persons, containers and vehicles and thus convey the disease to other premises, we were told by the Ministry of Agriculture that it was extremely difficult to assess how much disease had been transmitted in this way during the 1967/1968 epidemic. However, investigations were carried out, in the period from November, 1967 to January, 1968, by the Animal Virus Research Institute, in collaboration with the Central Veterinary Laboratory into the amount of foot-and-mouth disease virus present in milk sampled from various sources in Infected Areas. Their findings are given in Table IX and indicate that some samples of milk contained high concentrations of the virus.
Quantity of Foot-and-Mouth Disease Virus in Milk from Various Sources
in Infected Areas
Number of samples tested
Number of samples positive
Number of infectious particles per ml.*
(Average or range)
Bulk tankers .. ..
Churns .. .. ..
Bottles .. .. ..
Farm storage tanks ..
Cows .. .. ..
Bulk storage tanks ..
102.5 to 104.0
Trace to 105.5
Trace to 102.5
* Number of infectious particles indicated by log scale.
Thus 102=100, 105=100,000 and so on.
96. There are two risks associated with the bulk collection of milk as distinct from churn collection at the farm gate; the visits from farm to farm by the bulk milk tankers and the possibility of releasing contaminated air from the tankers. The latter risk during transportation is now considered not to be as great a danger as was at first thought but precautions were taken to minimise the danger from this source and in December, 1967 suitable filters were fitted to the air exhausts on bulk milk tankers. The risk from bulk milk tanker collection was, in the case of this epidemic, assessed as only marginally greater than the risk associated with churn collection.
97. The 1967/1968 epidemic was the most serious experienced in Great Britain within this century. The numbers of stock slaughtered during the period October 25th, 1967 to June 4th, 1968 were 211,825 cattle, 108,345 sheep, 113,766 pigs and 51 goats. The agricultural industry was gravely affected and the consequential disturbance and loss to many other interests were substantial. Industries relying on agriculture for their raw materials or for their sales were affected by the controls governing movements in and out of Infected and Controlled Areas, and sporting, leisure and other social activities were upset. Among the sports most seriously affected were horse racing, fishing, hunting,
football, car rallying, cross-country running, camping, canoeing, gliding, and mountaineering. Some of those whose livings were associated with these activities suffered considerable financial loss.
98. It is impossible to put forward a reasoned estimate of the total cost of the epidemic to the community as a whole. This would mean attempting some assessment of the losses caused to many organizations and persons outside the agricultural industry; it would mean attempting to put some value on the inconvenience and mental strain caused to many individuals both in agriculture and generally, not only by the necessity of slaughtering a vast number of animals but also by living and working under the unpleasant and restrictive conditions which were imposed during the epidemic. We feel, therefore, that it is reasonable to attempt to assess only the cost relating to the agricultural sector of the economy, to industries and services ancillary to agriculture, to the public sector and to consumers. These costs can usefully be divided into direct costs and indirect costs.
99. The direct cost of the 1967/1968 epidemic is estimated at £35.1 million largely made up of costs borne by the Ministry of Agriculture. The main item in this total is the cost of compensation which is provisionally estimated at £26.66 million. Another large item consists of payments for valuing, slaughtering and burying or cremating animals, and for disinfection; these amounted to some £4.2 million. Another major item is the additional staff costs incurred by the Ministry of Agriculture which amounted to some £2.8 million. Other direct costs are included in the total, such as special ploughing grant payments and the £ for £ extra compensation scheme.
100. The indirect costs might be divided into two groups. The first group would cover the loss of income arising from the slaughter of diseased animals and animals that had been in contact with them, for though the farmer is fully compensated for the slaughter of his stock his is still involved in losses. Com-pensation represents the capital value of the farmer’s slaughtered herd which enables him in due time to replace his stock-assuming there has been no upward movement in prices. The operation of the various control measures, however, normally introduces a delay between the time of slaughter and of replacing stock, and because of this and other factors the farmer loses income for which no cash compensation is made. The next group would include costs arising from the general disruption of agricultural production, marketing, and distribution following the imposition of control measures. For long periods during the 1967/1968 epidemic movements of stock were substantially restricted. In particular, the normal pattern of store stock production and marketing was seriously disrupted; from 24th November, 1967 to 31st January, 1968 for example, the whole of Great Britain was a Controlled Area and livestock markets were closed throughout the country.
101. Some of the indirect costs could be quantified if basic assumptions were adopted, but there is scope for a wide divergence of views in relation to these. Different sets of assumptions would result in considerable differences in the calculations and we considered that the limitations were such that it would require extensive research. However, in a prolonged outbreak the indirect
costs are likely to be proportionately greater. Such estimates as we received of direct and indirect costs ranged from £70 million up to £150 million. The estimates in the lower half of this range were the result of extensive studies. A point of some significance is that part of the indirect costs were borne by farmers who did not have the disease on their farms; we received evidence that a substantial number of such farmers had suffered heavy losses. A number of specific cases are discussed in a valuable study* carried out by Professor W. J. Thomas and Mr. J. Stewart, of the Manchester University Department of Agricultural Economics. The authors mention, for example, the case of two farmers who normally fattened store pigs and who lost several weeks’ output because they could not purchase such animals. Moreover they also had to keep on fat pigs beyond the optimum marketable weight thus incurring a loss of about £1 per pig. In one case the loss of income over the previous year was £430 and in the other £200. They also mention the case of six dairy farmers (for whom they had financial accounts) who incurred losses estimated to range from £5 per cow (or £4 per acre) to £20 per cow (or £10 per acre) because of the delay in getting cows and heifers into calf, because they could not get rid of cows which they would normally have culled, or because they incurred additional expenses on fodder to keep their animals indoors. None of these farmers qualified for compensation payments.
PREVENTION AND CONTROL OF
102. At one time some countries where foot-and-mouth disease was endemic accepted that they would experience recurring outbreaks of the disease , and steps were taken when an outbreak occurred to expedite its spread throughout flocks and herds so that the epidemic would be terminated as soon as possible. This attitude to the disease has disappeared except in the most backward areas. In other countries isolation of the affected animals has been practiced but this has usually been unsuccessful because of the highly infectious nature of the disease. These measures are still accepted by nomadic peoples whose husbandry is dictated by climatic conditions. In those tropical countries where wild animals share pasture with other livestock it may be necessary to accept recurring attacks of the disease although in some African countries measures are being taken to separate the wild from the domestic animals by stock-proof fences. In many such areas vaccination is now applied.
103. Control of foot-and-mouth disease as now practiced by many countries can be considered under two main headings: first the methods of preventing the introduction of the disease into a country with particular attention to the importation of meat from countries where the disease is endemic: second the methods of controlling the spread of the disease when it is present in a country either in endemic or sporadic form.
Control of imports
104. The best method of reducing the incidence of foot-and-mouth disease is by controlling imports of materials which may be contaminated by the virus. Most countries have legislation to control such imports.
105. The slaughter policy is only acceptable to countries or areas of countries where foot-and-mouth disease is not endemic and where introductions of the disease are relatively infrequent. It may be applied alone or in conjunction with a vaccination scheme (see paragraphs 119 and 123). The slaughter policy alone would be applied for example in Australia, Canada, Ireland, New Zealand and the U.S.A.. The success of the policy depends on adequate veterinary resources, the co-operation of farmers in quickly reporting the disease when outbreaks occur, and rigid enforcement of movement restrictions and disinfection. It also depends on eliminating the sources of foot-and-mouth disease virus by rapid slaughter and disposal of carcases, tracing animals that have been in contact with infected animals, and restricting the movement of persons and animals in the area of the outbreak. In most countries there is legislation to provide for these procedures.
106. When foot-and-mouth disease is diagnosed the infected animals are destroyed and the carcases disposed of as quickly as possible. Steps are taken to eliminate the risk of animals that have been in contact with the infected animals spreading the disease. In some countries the carcases of slaughtered animals are disposed of by burying or burning on the farm and in others by removing animals>alive or dead>in specially constructed vehicles to destructor plants. Sometimes the carcases are sterilised and processed for manufacturing purposes, but they may be salvaged for human consumption if they are apparently healthy.
107. There have been significant advances in the production of foot-and-mouth disease vaccines and their application in the field over the last fifteen years. There are two forms of vaccine: (i) inactivated vaccine and (ii) live attenuated vaccine. Inactivated vaccine is ideal for use in countries wherefoot-and-mouth disease is endemic. Great improvements have been made in the preparation of potent inactivated vaccines and these are used in most countries which have adopted vaccination policies. In some centers of research, including the Animal Virus Research Institute, much effort has been directed in the past ten years towards developing live attenuated foot-and-mouth disease vaccine. However, the highest standards of safety and potency have not been attained and the application of this type of vaccine is limited to a few areas. Its successful use reduces the frequency and extent of epidemics and it has been used as a preliminary to a more comprehensive scheme of vaccination with inactivated vaccine.
108. Of those countries that have replied to our questionnaire the following incorporate general vaccination in their control programmes:
Argentina France Kenya
Belgium Federal Republic of Netherlands
Botswana Germany Switzerland
Brazil Italy Uruguay
109. The types and sub-types of foot-and-mouth disease virus that give rise to the disease in a particular area are usually predictable, and countries that practise vaccination use vaccines containing the virus types and sub-types appropriate for their areas. (The vaccines are referred to as monovalent, bivalent, trivalent or polyvalent depending on the number of different virus types they contain.) In Argentina, Brazil, France, the Federal Republic of Germany, the Netherlands, Switzerland and Uruguay cattle are vaccinated with trivalent vaccines which contain sub-types of three main types of virus. The sub-types may be varied from time to time. In 1968 the sub-types in use were
Argentina: A24 : 01 : C3
Brazil A24 : 01 : C3
France A* : 01 : C1
Netherlands A10 : 01 : C1
of Germany A5 : 01 : C1
Switzerland A5 : 01 : C1
Uruguay A5 : 01 : C3
*At present being classified for sub-type by World Reference Laboratory,
110. Some strains of foot-and-mouth disease virus have a wide antigenic spectrum and when incorporated into vaccines give a broad measure of protec- tion against a number of sub-types. It has also been shown that animals that have been subjected to routine vaccination on a number of occasions will be better protected against a range of sub-types than those that have received vaccine on only one or two occasions. General vaccination may therefore give some protection against a sub-type which is introduced into an area for the first time. This may not always be the case and if a new sub-type has to be incorporated in vaccine which has to be manufactured a minimum period of two months, to allow for carrying out efficacy and safety tests, is usually required before the vaccine is ready for use. However, world monitoring services (see also paragraph 120) should allow sufficient notice to be given of the spread of new sub-types and thus allow their early incorporation in the vaccine. In an emergency, for example in the face of a rapidly spreading epidemic, vaccines that had passed the safety tests could be used without waiting for the results of efficacy tests and so reduce the waiting period considerably. The same procedure could apply if a new virus type had to be incorporated in the vaccine.
111. The results of experiments at the Animal Virus Research Institute given in the Figure IV overleaf show the antibody production (which is related to protection) in cattle following a single injection of vaccine in which aluminium hydroxide is used as an adjuvant. In animals not previously vaccinated (line B) antibody is produced by the fourth or the fifth day, and by the sixth day is sufficient to resist an average challenge of foot-and-mouth disease virus. It is considered that by the seventh day, 85 per cent of vaccinated cattle would have achieved a sufficient level of antibody (1.5 on the scale used) to be immune to the disease. In cattle that had been vaccinated previously there is a greater and more rapid antibody response (line A). Antibody to a particular sub-type of virus is also produced even when the sub-type used in the vaccine originates from a different strain (line C), but the response is not so rapid and it does not reach as high a level. In all three immunisation procedures (A, B and C) after about a month there is a gradual fall in antibody level and by the fifth or sixth month it may be undetectable. A similar response to foot-and-mouth disease vaccine occurs in sheep but in pigs it is much less satisfactory.
112. Work on oil adjuvant foot-and-mouth disease vaccines has shown promise and has already reached the stage of field trials. These vaccines are likely to give a reasonable degree of protection within three or four days of vaccination, to prolong the period of immunity and to be almost as effective in pigs as in cattle. Oil adjuvant vaccines that are available at present may produce a tissue reaction around the site of the injection, particularly in pigs, but there is reasonable promise that this drawback will be overcome.
113. Primary outbreaks often occur in pigs and thus theoretically there is an excellent case for vaccinating them. But because of the rapid turnover of the pig population and because hitherto there has been no really satisfactory vaccine for pigs, general vaccination of this species is not usually practiced. It is known that in countries with a vaccinated cattle population the disease sometimes remains undetected in pigs for a period and is only revealed when young unvaccinated susceptible cattle are exposed to infection. These animals are described as “indicators” or “revealers” because they show the presence of latent disease. Furthermore, sheep may be very resistant to disease and there is
NEUTRALISING ANTIBODY* RESPONSE OF CATTLE TO
Antibody level is given as LOG10 of the geometric mean titres of a number of sera.
The broken line indicates the level at which protection may be expected.
*Neutralising antibody gives an indication of protection.
0 Heterologous vaccine is prepared from a different but closely related
strain from the one used to measure the antibody.
Source:- Miinistry of Agriculture
a danger that they may harbour the virus for long periods; its presence would only become apparent when they come into contact with, and transmit the virus to, susceptible animals.
114. Young animals of all species can absorb antibodies from immune dams through colostrums (the first milk) in the first 24 to 36 hours of life. These maternal antibodies may confer protection, which varies from a few weeks to a few months, after which the young animals become completely susceptible. Maternal antibodies inhibit the response to vaccination and for this reason, in countries with general vaccination programmes, young animals are usually not vaccinated until they reach the age of four to six months when maternal immunity is lost. In the Federal Republic of Germany, however, calves aged two months are vaccinated on the assumption that either the animal is already protected by maternal antibodies, in which case the vaccine will not induce more protection, or that the animal is not immune and will respond satisfactorily with the development of antibodies.
115. In order to be successful a general vaccination scheme need not necessarily cover the entire susceptible livestock population of a country. A scheme covering a high proportion of the population, although not ensuring that every animal is immune, nevertheless builds up a national herd immunity which limits the number of primary outbreaks of foot-and-mouth disease and which breaks the chain of transmission of the virus, thereby also limiting the number of secondary outbreaks. In those countries in Europe where general vaccination has been adopted it is usual to protect only cattle.
116. The schedule of doses of foot-and-mouth disease vaccine varies in different countries. In France where animals are vaccinated only once a year, the operation is spread over the whole year so that the entire cattle population is never wholly susceptible. In the Netherlands vaccination takes place in the Spring, but any young animals that have attained the age of four months are vaccinated in the Autumn; other young animals are vaccinated as they are moved off the farm. In Argentina cattle are vaccinated three times a year and from the beginning of 1969 sheep are being included in the vaccination scheme.
117. In European countries vaccine is administered by veterinarians but in other countries, for example Argentina, the veterinary corps is insufficient in numbers to make this policy practicable and vaccination is supervised by local livestock committees which have farming and veterinary members.
118. The burden of cost of vaccination is spread in various ways but in general the farmer pays, either directly or through marketing or co-operative associations, in part or in whole. Where general vaccination is practiced farmers appear to be satisfied that it constitutes a good insurance against the risk of infection and the consequential disturbance, loss of profits and, in some cases, of valuable livestock.
119. Many European countries employing general vaccination also employ a slaughter policy. Outbreaks of foot-and-mouth disease are dealt with by slaughtering the infected animals and sometimes those that have been in contact with them. These countries may also apply ring vaccination round the area of an outbreak, over a distance of from one to three miles. (See paragraph 123). These additional measures>slaughter and ring vaccination> have contributed
considerably to the success of general vaccination campaigns and may now be largely responsible for maintaining the improved situation. The vaccination campaigns in Belgium, France, the Federal Republic of Germany, the Netherlands and Switzerland have undoubtedly been successful, although these countries still have an epidemiological problem among their large susceptible pig population (see Table III).
120. Barrier vaccination involves the vaccination of all susceptible animals in a buffer zone to prevent foot-and-mouth disease spreading from one area to another. The successful application of barrier vaccination depends on the knowledge of the distribution and movement of the types and sub-types of the virus. The international agencies which help in this task are the Office International des Epizooties, (O.I.E.), the Pan American Foot-and-Mouth Disease Center, the European Foot-and-Mouth Disease Commission of the Food and Agricultural Organisation of the United Nations (F.A.O.), the Near East Animal Health Institute at Beirut (also part of F.A.O.) and the Inter-African Bureau for Animal Health. The Animal Virus Research Institute also assists in this work in its role as the international reference laboratory and is designated by F.A.O. as the World Reference Centre for typing and sub-typing of strains of foot-and-mouth disease virus. An example of barrier vaccination is to be found in Argentina, which maintains a buffer vaccination zone running east-west across the whole country to protect the provinces south of the Rio Negro; Denmark also uses barrier vaccination along its southern borders when there is a threat of the introduction of disease from northern Germany. Such vaccination may be carried out either with a monovalent vaccine if the type of virus is known, or otherwise with a polyvalent vaccine.
121. Barrier vaccination was successfully practiced when, from 1962 onwards, south-east Europe was threatened with the introduction of the type SAT 1 virus which had not previously occurred on the Continent. Vaccination measures, co-ordinated by the European Economic Community, the Office International des Epizooties and the Food and Agriculture Organisation, were introduced to prevent the spread of the disease. In November, 1964 the disease situation on the south-eastern borders of Europe was further complicated by the emergence of the sub-type A22 virus which spread rapidly from east to west through the whole peninsula of Anatolia and reached Greece. Investigations showed that only the homologous sub-type A22 vaccine would prevent further spread into Europe. Supplies of such vaccine were produced for use in buffer zones in Bulgaria, Greece and Turkey. In addition a vaccination campaign with sub-type A22 vaccine was carried out in parts of Turkey. Many European countries contributed financially and by seconding staff; the United Kingdom Government supplied approximately £550,000 in cash and in vaccine. The measures taken successfully prevented the further invasion of Europe by type SAT 1 and sub-type A22 viruses.
122. In Mexico a rather different form of barrier vaccination contributed to the control of a foot-and-mouth disease epidemic which started at the end of 1946. Early efforts to control the disease by a slaughter policy met with only limited success and a vaccination policy was introduced in large quarantine
zones which were established by starting barriers fifty miles from known outbreaks and moving towards the source of infection. Eradication of the disease was accomplished by August, 1951.
123. Control of foot-and-mouth disease by ring vaccination may be carried out in a country with a completely susceptible livestock population. It involves the vaccination of all susceptible animals in a prescribed area around an out-break and depends for its success on the rapidity by which diagnosis, typing the virus and vaccination are carried out. If a suitable monovalent vaccine is available, consisting of the type or sub-type similar to that of the virus responsible for the outbreak, it would probably be used on these occasions; failing this a trivalent vaccine, if it contained the appropriate type of virus, might be used. Vaccination may be carried out in conjunction with slaughter of the infected animals and those that have been in contact with them.
124. Ring vaccination is practised in Denmark>a country which does not import carcase meat and which is not subject to many primary outbreaks. All cloven-hoofed animals on the affected farm are slaughtered unless they are judged to be immune as a result of previous vaccination. Cattle and sheep (but not pigs) within a perimeter of at least six miles are vaccinated and this is usually completed by local veterinary surgeons within ten days of the outbreak. Animals in the vaccinated area are retained within this area for some time; in the past this was usually several months but now the policy is that these animals may move out after thirty days. Restocking of cattle is permitted after disinfection of the farm on condition that the new stock have been vaccinated against the actual type of virus responsible for the outbreak at least three weeks and not more than two months before they are moved on to the farm. Restocking of pigs can take place six weeks after disinfection. Calves born on the farm have to be vaccinated at an age of three to four weeks, and the vaccination is repeated every fourth month for twelve months. There is a general rule that for five months after ring vaccination, cattle and sheep moving into the vaccinated area must have been vaccinated at the same time as, or after, the ring vaccination; however this rule may be waived. Some of the animals when vaccinated could be in the early incubation period of foot-and-mouth disease and a small proportion of them could become carriers of the virus. However, the prompt slaughter of the affected animals at an early stage before much virus is shed may mean that the carrier state arises in very few, if any, animals. The importance of the Danish experience is that no problem has arisen as a result of releasing cattle from within vaccinated areas and allowing them to mix with susceptible animals in other parts of Denmark.
Measures to control the introduction of foot-and-mouth disease virus
125. Precautionary measures to limit the introduction of foot-and-mouth disease into Great Britain are provided for in legislation or in agreements, as set out in Appendices V and VII. Orders are in force covering:
Imported meat and meat products;
Imported meat wrapping materials;
imported hay, straw and grass;
imported sera and glandular products;
vehicles carrying livestock.
These control measures appear to have been generally effective except in regard to meat imports to which the Ministry of Agriculture have attributed the majority of foot-and-mouth disease outbreaks. We will therefore deal with this aspect in some detail.
126. The countries from which Great Britain imports meat fall into four categories:-
(i) countries free from foot-and-mouth disease, for example Australia
and New Zealand, to which no restrictions are applied;
(ii) countries where the disease is sporadic and slaughter is included in the control policy, for example Denmark, France, the Netherlands and Poland. The conditions which are applied to such countries include the requirement that the origin of the animals and the place of slaughter shall be at least 20 kilometers (about 12= miles) from any known outbreak of foot-and-mouth disease that has occurred within the last 28 days. A sudden upsurge in the number of outbreaks of the disease or a tendency for the disease to break out from controlled areas would call for immediate consideration of a general ban on imports from the country concerned. Imports are suspended when in the view of the veterinary authorities in Great Britain there is a risk of temporary loss of control over the disease;
(iii) countries or areas of countries in which the disease is sporadic and in which a slaughter policy is not normally practised but where movement control measures are adopted, for example South Africa. Conditions are imposed requiring certification that the origin of the animals is from regions which have been free from foot-and-mouth disease for at least six months;
(iv) countries where the disease is endemic and where the Bledisloe arrangements apply; these are Argentina, Brazil, Chile and Uruguay. (See Appendices VI and VII).
127. The Bledisloe arrangements were first introduced in 1928 and the four countries to which they apply, particularly Argentina and Uruguay, have exported large quantities of meat to Great Britain for a very long time. Under these arrangements these countries are permitted to export meat to Great Britain under less stringent animal health conditions than those which apply to other countries from which we import meat. The original Bledisloe arrangements (Appendix VI) were revised in October, 1968 (Appendix VII) following a visit to all four countries by a British veterinary mission. The revised arrangements require that only carcases from animals that have been properly vaccinated against foot-and-mouth disease shall be exported to Great Britain. Such animals are unlikely to develop infection if exposed to foot-and-mouth disease virus, or to harbour it, and therefore these revised arrangements will undoubtedly reduce the risk from meat imports.
128. Other additional disease precautions in regard to meat imports from these four countries have been introduced from time to time in the light of experience. In 1961 imports of pigment and pig offal were prohibited; this ban is still in force. In December, 1967>at the height of the 1967/1968 epidemic>a complete ban was imposed on the importance of South American meat and offal. On 15th April, 1968 the ban was removed from carcase beef and beef offal but was retained on imports of mutton and lamb including their offal.
129. The complete ban, imposed in December, 1967, was simultaneously applied to all other countries exporting meat to Great Britain with the exception of Australia, Canada, Finland, Iceland, New Zealand, Norway, the Republic of Ireland and the United States of America. As with the South American countries, the ban was removed on 15th April, 1968.
Control of outbreaks
130. Great Britain has relied on the slaughter policy for controlling foot-and-mouth disease since 1892 when an Act was passed authorizing the Board of Agriculture to carry out compulsory slaughter. A serious epidemic occurred in 1922 and although the slaughter policy was generally applied, some of the affected herds were isolated where the circumstances were such as to provide what were then considered adequate safeguards against the spread of the disease. Isolation was abandoned in 1925 and since then the slaughter policy has been rigidly applied. This has been the means of reducing spread to the susceptible livestock population of Great Britain which in June, 1968 numbered about 44 million, including approximately 11 million cattle, 27 million sheep and 6 million pigs. In the following paragraphs we give a brief description of the slaughter policy as it applies in this country at present; there are many administrative arrangements involved and we shall return to these in part II of our Report.
131. As soon as a suspected case of foot-and-mouth disease is reported the Ministry of Agriculture serves a notice on the farmer which prohibits movement on or off his farm except under the permit of the Ministry’s veterinary inspector. The inspector then examines the animals and if necessary he arranges for specimens from them to the tested at the Animal Virus Research Institute. He may impose restrictions on an area of five miles radius of the suspected outbreak which prohibits movement of all animals within that area except under licence. If the case is confirmed, an Infected Area of approximately ten miles radius is immediately declared. The actual extent and perimeter of an Infected Area varies depending on the physical or legal boundaries by which it can be defined and the availability of slaughtering facilities. No movements of animal may take place within an Infected Area except under licence; such licences are issued either for direct movement to a farm (where the animals must remain for fourteen days without further movement) or from a farm to a slaughterhouse, or to a fatstock market for slaughter within the area. The Infected Area Order imposes other conditions relating to the movement of certain classes of persons, animals and materials within an Infected Area. No licenses may be issued for movement of animals out of an Infected Area.
132. Where there might have been widespread dissemination of the disease, such as through a market or a dealer’s premises, it may be necessary to impose wider restrictions, that is Controlled Area restrictions, which prohibit movements and markets without a licence. The object of these wider restrictions is to control movements until animals that may have been in contact with infected stock have been traced and inspected by the Ministry’s veterinary staff.
133. Infected animals are slaughtered immediately the disease is confirmed; the remaining animals on the farm are slaughtered after valuation. The carcases are buried or, in certain cases where burial is not practicable, are burnt.
134. Formerly the carcases of animals which had been in contact with infected animals but which were at the time of slaughter apparently healthy were salvaged in Great Britain but this practice had been abandoned by 1927. Salvage was reintroduced during the second World War but it was condemned in the Gowers Report and thereafter was no longer practised. Cases have been recorded of infected material from salvaged carcases being introduced into swill and thus giving rise to further outbreaks. The Gowers Committee recorded the following incident >
“ The first case of the exceptionally severe epidemic in Dumfriesshire was reported on the 2nd June , in pigs owned by a dairy company at Holywood. The next day outbreaks occurred on two adjoining farms as well as at Lockerbie, some ten miles away. The evidence available indicated that these three outbreaks were either spread from the Holywood dairy or had a common origin with the outbreak there. That origin appeared to be meat salvaged from the outbreaks at Wigtown which was sent via a Dumfries butcher to a school-meal kitchen at Marchmont, Dumfries. Kitchen waste found its way to a piggery (about half a mile from the dairy company’s premises) where it was stored, unboiled, in bins in the open. Rooks abound in the neighbourhood, and it is known that they frequently fed from these swill bins. It is likely that they carried the infection to the dairy company, since there also the birds feed from feeding troughs in the open. Thirty-seven outbreaks followed in the vicinity of Dumfries”.
135. In isolated outbreaks of disease restocking of the infected farm is allowed 28 days after final disinfection or 42 days after slaughter, whichever is the earlier; but when there has been a number of outbreaks in close proximity these times for restocking relate to the time of the last outbreak in the area. It is usual to reduce the size of an Infected Area to about five miles round the infected farm fourteen days after the last outbreak and to remove restrictions after 21 days. Controlled Area restrictions are removed as soon as possible in order to permit livestock trading to be resumed.
136. Preparations for the emergency use of vaccine were made during the 1967/1968 epidemic. During the second half of November, 1967 it was decided to prepare contingency plans for an extensive ring vaccination programme as a second line of defence. A stock of type O1 monovalent vaccine
was acquired and a plan of campaign was drawn up in the first few days of December. Some five hundred veterinary surgeons who were not employed in the foot-and–mouth disease control programme were prepared to leave their normal work and commence vaccination. The plan assumed that full scale vaccination could be started within four days of a decision being taken to vaccinate and that about two million animals could have been vaccinated in ten days. In the event, the plan was not necessary as during December it became apparent that the epidemic was waning.
DISCUSSION OF FUTURE POLICIES FOR
137. There are three main policies for dealing with the prevention and control of foot-and-mouth disease which can be adopted either singly or in combination:
(a) Import policy>designed to reduce the risks of introducing the disease into the country by restrictions on imports which may carry the virus.
(b) Slaughter policy—designed to isolate and stamep out outbreaks of the
disease when they occur.
(c) Vaccination policy—designed either to limit the number of primary
outbreaks as well as the subsequent spread (general prophylactic
vaccination), or solely to limit the spread of the disease when primary
outbreaks occur (ring vaccination).
(a) Import Policy
138. There are a number of ways by which foot-and-mouth disease may be introduced into Great Britain; they have all been referred to in previous chapters and may be summarized as follows:
(i) wind tracks carrying airborne virus;
(ii) migratory birds;
(iii) travellers coming from abroad;
(iv) traffic from abroad;
(v) importation of semen;
(vi) importation of sera and glandular products;
vii) importation of hay, straw and other vegetable matter;
(viii) importation of live animals;
(ix) importation of meat wrappings which mayhave been exposed to
the risk of contamination by the virus;
(x) importation of meat and meat products.
139. The introduction of foot-and-mouth disease virus by wind and birds cannot be controlled. However, the improved situation regarding foot-and-mouth disease in the northern parts of the Continent of Europe over the past few years undoubtedly has reduced the risks from these methods of introduction and has probably been responsible for the reduction of the number of primary outbreaks in the east and south coastal areas of England. There are no suitable wind tracks or migrations from countries such as Spain. All our witnesses thought that the risk of introduction from Continental sources by wind and birds is now small.
140. International travel for business and pleasure is increasing every year. This trend is likely to continue. In 1957 the number of foreign visitors arriving in this country was about 1< million and by 1967 the number had increased to nearly 3= million; over 2 million of those who landed in 1967 arrived by
air. The number of British travellers abroad has also increased; in 1957 nearly 3 million of them returned to the United Kingdom and by 1967 this figure had increased to about 6= million. About 4 million of those who landed in 1967 arrived by air. All our witnesses acknowledged that there could be a risk of foot-and-mouth disease transmission from country to country by travellers although none rated it very highly. It seems that this risk may not be great but transmission of the virus by this means would often be impossible to prove. Although with the rising volume of travel the risk could increase, we think that satisfactory foot-and-mouth disease control programmes overseas will certainly reduce it. Some countries free of foot-and-mouth disease have taken elaborate precautions, when threatened with the introduction of the disease, to inspect passengers and baggage at the port of entry and to ensure that they pass through a decontamination barrier, but we consider that to do this effectively would be impracticable because of the magnitude of the problem.
141. The risk of introducing foot-and-mouth disease arising from vehicular traffic from abroad has also increased. This risk is greatest when animals or other potentially dangerous materials are transported. There are Statutory Orders (see Appeindix V) dealing with this matter which require the cleansing and disinfection of vehicles which have carried animals before they are used to carry other animals; these requirements, however, might not necessarily be implemented until vehicles have travelled far inland. We consider that such vehicles should be cleansed and disinfected at the ports of entry and that the present facilities for doing so are inadequate. Facilities should also be available for disinfection of personnel who come in contact with such vehicles.
142. The importation of semen, sera and glandular products and the importation of hay, straw and other vegetable matter is dealt with in Great Britain by legislation (see Appendix V). It was considered by all our expert witnesses that the importation of these materials under present legislation does not constitute a serious risk of introducing foot-and-mouth disease virus.
143. One of the major risks of introducing foot-and-mouth disease virus into Great Britain could be from the importation of live animals susceptible to foot-and-mouth disease. In this respect Great Britain exercises rigid control procedures(see Appendix V) which have apparently been successful in preventing the introduction of the disease by this means. There has never been an outbreak associated with animals imported under these Regulations, and our witnesses agreed that little or no risk was involved under present legislation.
144. The importation of meat, meat products and meat wrappings constitutes a serious risk particularly in relation to bones and offal (see paragraph 14). We think that the way in which offal is treated makes the risk from this source less than the risk from bones; in general there is little waste thrown away from offal before it is cooked. We accept however that tainted offal might be thrown away without having been cooked and there is also a risk from wrappings and residual blood from offal.
145. Great Britain imports meat and meat products from countries which are completely free from foot-and-mouth disease, such as Australia and New Zealand, from countries where the disease is sporadic, and also from countries where it is endemic. There is no risk of introducing the disease by the importation of meat and meat products from countries which are free from the
disease, but there are differing degrees of risk when imports are from countries where the disease is endemic or sporadic, depending on their disease status.
146. The quantity and type of meat and meat products imported into Great Britain from countries where foot-and-mouth disease is sporadic are included in Appendix VIII. Such imports carry a risk of introducing the disease and although strict control legislation (see Appendix V) is enforced, there clearly remains a potential risk in importing meat and meat products from countries suffering from sporadic outbreaks. This risk would diminish as the animal health situation in such countries improves. Effective controls must depend on the ability at short notice to revoke licences whenever dangerous situations arise in exporting countries. We consider it essential that the importation of meat and meat products should be governed by a machinery which is sufficiently flexible to cope swiftly and adequately with the many differing and often fast changing situations which can arise in these countries. We are satisfied that the general use of revocable conditional licences must be accepted as the only satisfactory means of providing this essential flexibility.
147. The figures of meat imports given in Appendix VIII also include those from countries where the disease is endemic, namely Argentina, Brazil, Chile and Uruguay. We consider that the risk of introducing foot-and-mouth disease into Great Britain in respect of imports from these countries is always high. We have explained in Chapter II that foot-and-mouth disease virus can remain viable in various parts of an infected carcase for long periods and although the virus has been isolated from meat responsible for an outbreak of the disease on only one occasion in Great Britain, we are satisfied that the majority of primary outbreaks in this country have been caused by imported meat from countries where the disease is endemic.
148. Table X overleaf gives the origins to which the Ministry of Agriculture attributes the primary outbreaks of foot-and-mouth disease in the period 1954 to September, 1967. Of the 179 primary outbreaks, 74(41 per cent) were attributed to imported meat and meat wrappings from countries where the disease was endemic. It may well be that some of the 40 outbreaks (22 percent of the total) to which no origin could be attributed were also from meat sources.
149. Great Britain has recognised for a long time the danger of importing meat from Argentina, Brazil, Chile and Uruguay and over the years has made arrangements and imposed certain restrictions regarding meat imports from these countries to reduce the risks (see paragraph 127 and Appendix VI). The situation before the 1967/1968 epidemic was that beef, lamb and mutton, together with their offal, could be imported under the Bledisloe arrangements but there was a complete ban on the importation of pig meat and pig offal.
150. At the height of the 1967/1968 epidemic further restrictions were simposed on meat imports from Argentina, Brazil, Chile and Uruguay (see paragraph 128). In April, 1968 restrictions on imports of carcase beef and offal were removed but the bans on pigmeat and offal, and mutton and lamb and their offal, have remained in force. Further, as a result of a veterinary mission which visited these countries in May, 1968, the Bledisloe arrangements were revised and put into operation in their new form in October, 1968 (see Appendix VII).
Origins Attributed by the Ministry of Agriculture to
Foot-and-Mouth Disease Outbreaks from 1954 to September, 1967
Attributed by ministry of Agriculture to:
Imported Meat and Meat Wrappings
Birds and other Origins
From countries where the disease is:
From unidentified countries
1955 .. .
1956 .. .
1957 .. .