From: "Ruth Watkins" ruthwatkins@supanet.com 

To: "maryatwarmwell" maryatwarmwell@hotmail.com

Sent: Thursday, May 17, 2007

Subject: vaccination against FMD in piglets

The details are not very clear but here are some observations on the comments

1. In pigs especially intensively reared pigs inside there can be  enormous shedding of FMD, some types more than others, for instance as an  aerosol thus quickly exposing any pig in the shed and travelling at least locally on a farm in air currents ie to the neighbouring shed etc This is greater in pigs than other animals it was dreaded in 2001 but never happened.

2. Piglets come along very quickly in large numbers in the sheds with breeding sows. They need to be vaccinated fairly quickly though I presume they imbibe anitbody from the sow's milk when she is fully vaccinated. It has been a problem in FMD outbreaks in Taiwan some years ago for instance

 3. It is possible that a piglet's response to a single vaccine - the highly potent antigen vaccine - may not be as great or quick as an adult or a different animal. Normally at least two doses of an antigen vaccine are needed as in influenza and it is a bonus that a highly potent vaccine has been developed for FMD effective after one dose.

4. Immunity raised by a vaccine particularly if the response was not good might be overcame by a massive exposure to the infectious agent as could occur in an intensive piggeries.

5. Infection can also occur if the exposure is before the development of immunity or a good response ot the vaccine.

I don't think there is anything new or any reason to be perturbed by the pig article. It is unfortunate that vaccination in intensive rearing conditions does not work so well especially in piglets. Perhaps problems of formulation can be improved for pigs.

ruthwatkins@supanet.com