• Begin wide spread vaccination if the initial approach of stamping out the animals is beyond control.
• Stop the massive blind killing, an antiquated practice in the age of modern vaccines and diagnostics.
• Quickly and extensively monitor and detect FMDV infections/carriers using UBI FMDV differential diagnostic tests.
• Prevent disease spread by killing infected/carrier animals detected by the tests.
• Continue to monitor progress toward FMDV eradication by using the diagnostic kits until reaching FMD free status.
• Continue the widespread vaccination program until free of outbreaks for at least 24 months.<top>

• Traditional serological FMDV diagnostic methods cannot distinguish vaccinated animals from infected animals. Thus, they believe that vaccination will complicate their FMD-free status.
• Vaccination using traditional killed virus vaccines may itself lead to disease outbreak, due to accidental contamination by live viruses during the vaccine manufacturing.

Once a nation has eradicated the disease from an area, thus gaining FMD-free status, not vaccinating the animals with the currently available killed virus vaccine allows the country to maintain a sensitive means of detecting whether the virus has crept back in again, as any accidental infection will lead to a full-blown outbreak.

However, this strategy of "non-vaccination" is a gamble. It assumes that the nation will be able to contain the outbreak by stamping out the infected herds quickly enough to prevent real damage and thereafter, in the absence of further outbreaks and vaccination, quickly regain its FMD-free status.

Furthermore, the non-vaccination policies are based on the calculation that such outbreaks will happen rarely and be detected quickly so that this calculated vulnerability will be cheaper than the method of routine mass vaccination.

Another concern for vaccination is that there was one case report which stated that in a few animals vaccinated with the killed virus vaccines, FMDV can still cause subclinical infection. It is not clear whether this can infect other animals, or how long such subclinical infection persists. The theoretical risk that this might have happened means meat from a vaccinated animal might be carrying the virus. Until now, standard tests could not distinguish whether an animal has antibodies to infection or to the vaccine. Other regions trying to remain FMD-free without vaccination will not buy meat from countries that vaccinate because some vaccinated animals may harbor such subclinical virus.

For the above reasons, the "FMD-free, non-vaccination" policy has been adopted by most of the industrialized nations in order to maintain their FMD-free status.

From the world trade point of view, there is another benefit to the non-vaccination calculation. If a country does not vaccinate for FMD and other livestock diseases, that country can refuse imports from countries that have the disease, or that vaccinate. These vaccinating countries may be poorer countries with lower production costs, who may offer lower prices. Therefore, this "FMD-free, non-vaccination" policy can constitute an import barrier in today's world trade.

The official statement from EU regarding why it does not vaccinate is that it must protect its exports to FMD-free countries. However, such exports only amounted to 5 per cent of total EU meat sales in 1999 (which reached $17 billion), prior to some import bans due to BSE.

More than 78 per cent of meat sales in 1999 were domestic. If the "FMD-free, non- vaccinating" policy did not constitute an "IMPORT BARRIER", some of the domestic meat sales might have been lost to foreign competitors who vaccinate for FMD. <top>

• The risk of accidental infection increases with global trade and travel;
• The risk of deliberate infection is considered non-negligible by many intelligence agencies; and
• Detecting an outbreak before it has spread far is made more difficult by modern livestock stocking densities, centralized marketing practices and a decline in veterinary surveillance.

The current outbreak in Europe suggests not vaccinating may not be cheaper after all. <top>

Despite the EU non-vaccination policy, Belgium and the Netherlands have formally asked other EU countries to consider vaccinating routinely for FMD again. They have not said how this would be coupled with monitoring for subclinical infection. (Such routine prophylaxis must be clearly distinguished from the emergency vaccination permitted and now planned in the EU to contain outbreaks. All such emergency vaccinated animals must be destroyed before the region regains its disease-free status under current rules.)

Answers to the last few questions have incorporated the essay written by Debora MacKenzie, a European correspondent for New Scientist magazine. <top>

First, mass culling policy dictates the killing of many adult animals which would otherwise have survived infection, albeit with perhaps a 10 percent loss in productivity. Despite this mass culling policy, a legacy of surviving but infectious animals are left behind, which would perhaps take years to eliminate in order for the USA to return to FMD-free status.

Japan and South Korea account for over 60 percent of US beef and pork exports, and will ban imports of both from the US at the first report of a US outbreak. Australia and New Zealand will be happy to fill the gap. If US adopts a ring vaccination and selective culling policy, the outbreak will only result in a 10 percent loss in meat production as a result of an outbreak. This slight decrease in meat production will not affect the capacity to export to markets other than Japan and Korea.

Second, the logistics of slaughtering and disposing of possibly millions of head of livestock quickly overwhelms capacity. During the FMD outbreak in Taiwan in 1997, 4 million pigs were culled at a peak rate of 130,000 per day after the army got up to speed. Assuming the US Army could do the same on the larger US feed lots, it will still take 30 days to kill and depose of 4 million animals; 30 days in which the disease is still spreading. It is questionable, however, whether the public would stand for the spectacle of the US Army or National Guard shooting livestock.

Third, the risk of delays due to litigation are great. Farmers and national associations of breeders would seek injunctions. Animal rights and environmental groups would do the same. Slaughtering could be held up for weeks. Also the substantial financial resources necessary for a big emergency would exceed existing provisions and require additional legislation, preceded by much debate, before being approved. Even emergency funds from the White House would take time to arrive. The general experience with public health authorities has been that they will always hope that the outbreak will be contained with minimum expenditure, inevitably leading to too little funding too late. There is no reason to believe animal health authorities will react differently.

Models exist that purport to show US conditions under the most optimistic circumstances. If culling of 95 percent of latently infected plus infectious herds can be achieved beginning in the second week after recognition of the first outbreak, "only" 20 percent of an affected region's herds need be destroyed to achieve control. But if culling to that level is delayed by just one week, the eventual destruction will have to be more than 90 percent. It is unlikely that any state agency will be able to move that fast, or be able to cull to that level.

Finally, a recent analysis of the potential cost of FMD in California projects direct costs, plus production losses, plus trade losses would sum to around US$8000 per head culled, or US$ 8 billion per million head -- and this may be a conservative estimate. Twenty percent of the cattle in Texas alone is 1.6 million head.

References:

Ekboir J 1999. Potential impact of Foot and Mouth Disease in California. Agricultural Issues Center, Div Ag & Nat Res, Univ. Cal. Davis.

Yang PC, Chu RM, Chung WB, Sung HT 1999. Epidemiological characteristics and financial costs of the 1997 Foot and Mouth Disease epidemic in Taiwan. Vet Rec 145 (25): 731?734.

The above discussion on "why mass culling?as opposed to selective culling- although being used in the UK for the current outbreak is out of the question for the USA" is adapted from the contribution by Dr. Jack Woodall woodall@bioqmed.ufrj.br, originally appeared in www.promedmail.org on April 4, 2001. Dr. Jack Woodall's official affiliation is at: Dept. of Medical Biochemistry, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.<top>