Andrew Stephens - after working as a vet with dairy cattle in West Wales for a few years Andrew Stephens took up a research post with the Veterinary Epidemiology and Economics Research Unit (VEERU) at The University of Reading.
In response to comment written on the farmtalking forum he wrote this week (Aug 13 2007) on the misconception that vaccine is useless 'because you need to know the exact strain'.
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"....Then use a multivalent vaccine - formulated according to most likely sources of infection at any time. Not beyond the wit of epidemiologist to identify most likely type(s) of virus in circulation - or potentially able to escape as in latest situation - is this not the approach taken with formulating human flu virus vaccine each year?"
He went on to describe the composition of such vaccines.
"Decivac FMD DOE is an inactivated oil adjuvanted vaccine for the active immunisation of pigs, cattle, buffalo, sheep and goats against Foot and Mouth Disease.
Decivac FMD DOE may contain antigens of the FMDV types O, A, C, Asia1 and SAT1, SAT2, SAT3 (monovalent or multivalent).
The actual combination of antigens depends on the local situation. Each dose (2 ml) of vaccine contains at least 3 PD50 of the virus types indicated.
The FMD viruses are propagated on BHK cells, chemically inactivated and subsequently purified and concentrated.The resulting antigens are stored at ultra low temperature until formulation of the final vaccine.'
He commented that the correspondent to the forum who takes such an anti-vaccination stance did not ".. address the issue of whether it is sustainable to seek to maintain the 'FMD-free without vaccination' population of susceptible livestock in countries with a high input-high-output agricultural system and a complex food distribution system of which the slightest disruption has severe economic consequences?"
He said, " I guess you may consider this to be a political question as opposed to a (strictly) scientific question?
But surely the political and social factors do influence policy - I worked at one time in a research group that pioneered a social cost-benefit approach to planning and assessing animal disease control measures; can one ignore social costs (and benefits)?
All this corresponds with another email received from Dr Ruth Watkins this week on the subject of vaccination and its misconceptions. Particularly relevant to those who think that vaccination amounts to a sort of nasty chemical cocktail being pumped,willy-nilly into animals. Dr Watkins wrote (Aug 12)
- "We vaccinate against lots of things and those of us who have at least had tetanus and diphtheria vaccinations, which are toxins adsorbed (sic) to aluminium hydroxide or phosphate a mineral carrier, join the billion or so who have had this and who have remained well.
It has of course saved millions of lives of people who would have died from tetanus or diptheria.
Adjuvants are added to dead vaccine (killed virus) or protein (toxin) used to vaccinate to ensure our immune system takes them up to make an immune response an form protective antibody.
In the case of FMD, if I recall correctly, in order to make the vaccine of high potency so that a good response is made to one shot of the killed vaccine, a mineral oil is used. This may be irritant and it is not acceptable for humans to receive such a vaccination but it is not inedible.
I don't believe steroids are used in any vaccines. It would be ludicrous to suggest, on the basis of giving the FMD vaccine suspended in mineral oil as an adjuvant, that the vaccinated animal must then be killed.
All our lives we are exposed to viral bacterial and parasitic infections, bitten by insects that inject their saliva and we swallow goodness knows what so that our digestive system is exposed also to a myriad of proteins and other substances. Even if your correspondent went back to the Stone Age he would have had viruses (herpes, adenoviruses, respiratory viruses, hepatitis B etc) bacteria, commensal and pathogenic, eg M tuberculosis, and also been loaded with worms in the gut and blood even lungs too. He would have had lice in his hair and fluke in his liver, and been exposed to animal viruses and bacteria when he killed and butchered freshly killed animals to eat (this is believed to be the source of HIV virus infection in humans, HIV-1 from the chimp). The tiny dose of protein given in modern vaccines and the relative freedom from worms and insect bites mean that modern man has a fraction of the exposure of his Stone Age counterpart.
We do however have exposure to man-made molecules that do not degrade in the environment, and to synthetic hormones such as oestrogens in the water, which is a concern but they are not in the vaccines used.
On the question of whether the UK will have to "keep vaccinating if it starts", Andrew Stephens wrote:
- So what? The vaccinations could be scheduled along with other health
care/ management interventions in a herd or flock and the whole of
the UK would thereby be protected from any future re-introduction of
FMD virus. The costs would be bearable vs. the risk I'd have thought.
With ever increasing movements of people and goods around the world - and within the UK - is it sustainable to believe that one effectively maintain an 'FMD-free without vaccination' (ie.susceptible) population of animals in any country with a high input-high output agricultural system and a complex food distribution system of which the slightest disruption has severe economic consequences?"
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