FOOT-AND-MOUTH DISEASE IN 2000-2001 PERIOD.
Raul Casas Olascoaga*
*Direct Advisor of the Minister of Livestock, Agriculture and Fisheries
Summary presented on behalf of the Ministry of Livestock, Agriculture and Fisheries of Uruguay in the INTERNATIONAL CONFERENCE ON CONTROL AND PREVENTION OF FOOT-AND-MOUTH DISEASE, BRUSSELS 12-13 DECEMBER 2001.
Livestock raising is the principal agricultural activity of Uruguay and the mainstay of the economy, contributing more than 65 percent of yearly Uruguayan exports in the form of meat, wool, milk, hides and industrialized livestock products. The moderate climate and the even distribution of precipitation make it possible to pasture stock under natural conditions throughout the year. The area of Uruguay is 176,215 km2 and the human population 3,146.200. In 30 June 2001 livestock numbered 10.6 million cattle, 12 million sheep, 480,000 horses, and 270,000 pigs. The number of farm is 57.131 and the exploited land surface is 16,419.683 (Year 2000)
The OIE recognized Uruguay as a country free with vaccination in May 1994. Uruguay suspended vaccination against FMD in June 1994. In May 1996 the OIE recognized to Uruguay the status of free of FMD without vaccination.
On October 23rd, 2000 clinical signs of FMD were recognized on a farm, in the Artigas Department very close to the frontier with Rio Grande do Sul, Brazil. The affected herd had 322 cattle, 63 sheep and 47 pigs. The disease first appeared in the pigs and 9 suckling pigs died suddenly. The next day OIE was officially notified and two days later PANAFTOSA identified the virus as type O, that subsequently was characterized as subtype O1.
The outbreak was eradicated by the stamping-out of diseased animals and exposed contact animals within the area of the outbreak and in the suburban area of the Artigas City. The total numbers of animals destroyed were 6924 cattle, 12,371 sheep and 257 pigs. A zone with a radius of 25 km was fully quarantined. All depopulated farms were cleaned and decontaminated. Sentinel young steers and pigs were placed on the premises 30 days after the last depopulation. A serological survey was conducted in a buffer zone with a 5-25 km radius from the infected farm. All the samples were negative to FMD antibodies. The whole Artigas Department was regionalized and quarantined for a considerable period of time. OIE re-established the status of free country on January 25 of 2001.
Unfortunately, in April 2001, the country again lost this status as a consequence of the introduction and spread of the type A epidemic from Argentina. On the 23rd of April 2001 a vesicular disease outbreak was denounced in Palmitas in the Soriano Department, approximately 70 km to the Argentina boundary separated by the Uruguay River. The infected farm had 430 cattle and 640 sheep, of which 39 of 1-2 years-old steers showed FMD typical signs and lesions. The next day, the veterinary services confirmed the FMD clinical diagnose. On day later, serums of the affected animals were found positives to the VIA and ELISA tests. More than a week later, PANAFTOSA confirmed the virus to be type A( virus strain related to A24).
On April 26th a second outbreak was detected in the neighboring farm with 773 cattle, 474 sheep and 10 pigs. Interdiction of the affected farms was enforced immediately with a complete stand-still of animal movements and trade. Simultaneously several FMD outbreaks occurred in the adjacent Colonia Department at 25 km from the Uruguay River.
The distance between the index foci in Palmitas, Soriano Department and the outbreaks in Colonia Department is about 40 km.
The next day the affected and exposed animals were stamping-out and buried. (5,093 cattle, 1511 sheep and 333 pigs were destroyed). However, on the 29th the Government was forced to suspend the stamping-out procedure due to the strong resistant of the local farmers and the rapid FMD spread to other departments of the country
In the Soriano Department and the adjacent Colonia Department, co-exist an intensive cattle dairy industry as well as cattle fattening and agricultural production systems. The factors that include favoring the dissemination of the virus in those Departments are intense movements of agricultural equipment and machinery, trucks for the transport of beef cattle and milk. Moreover, the zone is economically very much integrated with the adjacent region of Argentina where active foci of FMD occurred in the neighboring Provinces of Entre Rios, Santa Fe and Corrientes.
Both departments were quarantined and on the April 26th ring vaccination was started in an area with a 10-km radius around the infected farms. On the 30th the vaccination was extended to form barrier in the the Soriano and Colonia Departments. However a few days prior to the recognition of the outbreak the epidemic had already spread to others regions of the country. From April 27th to the June 7th all movements, transits and trade of animals were prohibited in the whole territory of the country. O.I.E. and the countries were immediatelly notified and export of animals and animal products were suspended.
On May 5th a massive systematic vaccination was re-established in the total cattle population of the country. In order to protect the Brazilian livestock population against the introduction of the disease, the massive vaccination inmediately covered all Uruguayan departments adjacent the State of Rio Grande do Sul, Brazil. The first vaccination round ended by June 7th when movement and transit restrictions were relaxed. The re-vaccination round lasted from June 15th to July 22nd . A total of 24 million multivalent doses of FMD oil-adjuvant vaccines were applied in these two vaccination rounds (11,773.840 doses in the first round and 12,153.988 doses in the second round were distributed) to coverage a population of 12.6 million cattle in each round. The average rate of vaccination is 350.000 ( three hundred fifty thousand) cattle per day in each massive round of vaccination in the whole country. In each round the veterinary services establish a chronogram of vaccination scheduling routes, date and time. Most of the vaccination is done by the farmers and their auxiliaries and in some cases by private veterinarians. The official veterinary services have an active control of the vaccination procedures a farm level. The dairy cattle stock is vaccinated in one week and the vaccination rate is 67.000 heads per day.
By November 2001, 4.5 million young cattle were additionally vaccinated, each animal identified by ear tag tracking system.
The total number of outbreaks was 2,057 of which 264 were dairy farms. The distribution of FMD outbreaks is shown in Map No 1. The last outbreak occurred in San Jose Department on a dairy farm on August 21st. By the first week of October 2001, Uruguay was again free of FMD (more than 30 days of the last FMD case).
Graph No 1 shows the evolution of the outbreaks caused by type A versus in relation to the vaccination and re-vaccination campaign. It can be seen that at the height of the epidemic there were 40-60 new infected farms per day. Shortly after the end of the first vaccination round, in spite of the relaxing of livestock movement restrictions, the number of new cases decreased dramatically to single numbers. A few day after the completion of the re-vaccination round, there only were a few sporadic cases. Thus, Uruguay was able to control and eradicate this extensive outbreak with the application of livestock movement restrictions and the massive vaccination of the cattle population only, in spite of having a large fully susceptible sheep population in close contact and proximity to the cattle. The total cost of eradicating the epidemic was 13.6 million US$, of which 7.5 million were spend on the purchase of vaccine, and the remainder on indemnization of farmers, cleaning and disinfection and operating expenses.
Susceptible livestock populations are at risk when the first line of defense against the importation or re-introduction of FMD is not well maintained
International collaboration and maintenance of effective surveillance (counting with laboratory support) and transparent and rapid reporting systems is essential.
The transitioning from a “FMD free with vaccination” status to a “FMD free without vaccination status” requires a different mind set of all stakeholders and the preparation of flexible contingency plans and,
Breaking of the regional cycle of endemic and active virus niches of the disease by massive and strategic cattle vaccination campaigns;
Interruption of the cycle of virus transmission from primary endemic areas to secondary ecosystems ( epiendemic, sporadic and free ecosystems)
Vaccination of cattle only, in combination with livestock movement restrictions and trade was shown to control an extensive outbreak in a very short time, with minimal disruption of the rural society and economy.
Strong and continuos programs of education and training of the public and private veterinary services as well as farmers and public in general must be applied
FMD bank of purified and potent antigens and vaccines must be available for immediate use and application in sanitary emergency occurrences.
The O.I.E. criteria for regaining FMD-free status after using vaccination as an aid to eradication need to be reviewed.
International cooperation towards FMD control and eradication
has to be strengthened.
SOURCE: Direccion General de Servicios Ganaderos (DGSG), Ministerio de Ganaderia Agricultura y Pesca, R.O. Uruguay.