FMD: Why Not Vaccinate?

The question has often been raised if FMD is such a huge potential problem for the United State livestock industry, why don’t we just vaccinate and protect our animals?  The use of FMD vaccine presents several problems.

1) The vaccine must be of the correct type and subtype.  There are 7 major types of FMD virus and 60 subtypes.  Very little cross protection is provided between types and subtypes. Often commercially prepared vaccines contain a limited number of types and subtypes and may not provide any protection to the specific type causing the outbreak.

2) Vaccination does not prevent animals from developing a “carrier” status. Here the animal does not develop clinical FMD, but remains a carrier of the virus.  If this animal is allowed to remain in the herd and new, non vaccinated, animals are introduced they can become infected with FMD.  Animals can remain in apparent carriers for months to years.

3) Vaccination makes testing and removal difficult.  Often after an outbreak the affected country is trying to return to FMD free status.  If vaccinated animals remain in the population then serological testing is difficult.  Serological testing  cannot determine if an animal has a titer to FMD because of vaccination, because it is a carrier or because it has subclinical FMD (often seen in sheep).

4) There is an international organization, OFFICE INTERNATIONAL DES EPIZOOTIES (OIE), or The World Organization for Animal Health.  The role of the OIE is to set international standards for animal health issues and to insure fair trade.  As presented in the OIE mission statement:

In the world economy, the unimpeded flow of international trade in animals and animal products requires:

A) veterinary regulations designed to prevent the spread of transmissible diseases to animals and to human beings;

B) the harmonization of requirements for such trade, in order to avoid unjustified trade barriers.

The OIE is responsible for the certification the FMD status of member countries (currently 157 nations).  The United States, Canada, Mexico and all of Western Europe are members.  FMD is a disease that OIE actively monitors.  The OIE has established a warning system allowing Member Countries to take rapid action should the need arise. Within 24 hours of the occurrence of the first outbreak of a List A disease (such as FMD), or any other infectious disease that could have serious repercussions on public health or on the economy of animal production, the affected country reports the incident to the OIE Central Bureau.   The Central Bureau immediately sends a summary of the warning message by e-mail to  Member Countries.  This warning system allowed the USDA to respond to the FMD outbreak in the UK rapidly.  Once FMD has developed in an FMD, free country the OIE has established a series of protocols that must be complied with for that country to return to FMD free status.  If an FMD free country that has started a vaccination program, that nation cannot return to FMD free status until all vaccinated animals have been slaughtered and all vaccination programs have stopped.

Currently the UK is considering the use of vaccination to stop the FMD outbreak.  Although this may help in slowing the spread of the disease, this will have long term implications for livestock producers.  All FMD vaccinated animals will need to be permanently identified and slaughtered when possible.  The UK will be severely restricted in the exportation of livestock and livestock products.  It will take the UK years to return to FMD free status if vaccination is started.

5) OIE vaccination standards require two vaccinations one month apart, and this would provide protection for only six months.  All susceptible species (cattle, swine, sheep and goats) will need to be vaccinated.  The cost of such a massive vaccination program in the huge livestock population of the United States would be enormous.

Because of the problems associated with FMD vaccination, the United States, Canada and Mexico are much better off in preventing the introduction of FMD.  If an FMD outbreak does occur, the rapid identification and isolation of the outbreak are vital to restricting the problem to a limited area.  If a wide spread outbreak does occur and at some point a vaccination program is started it would limit our livestock export market for several years.  Currently the United States enjoys the status of being free of FMD and BSE.  If we retain that status it will provide US livestock producers a tremendous competitive advantage in the international market.

If you want more information on the OIE see:  http://www.oie.int/eng/OIE/en_oie.htm

USDA on FMD: http://www.aphis.usda.gov/oa/fmd/index.html

The information in this document has been reviewed by the Veterinary Staff at AzVDL .
If you have questions of FMD please contact me at the Arizona Veterinary Diagnostic Laboratory, telephone 520-621-2356 ext 18.

S Peder Cuneo D.V.M., MS, Diplomate ABVP Beef Cattle
Extension Veterinarian University of Arizona
e-mail cuneo@u.arizona.edu
telephone 520-621-2356 ext 18