Foot-and-Mouth disease is exotic to the U.S. but the USDA-Animal and Plant Health Inspection Service (APHIS) has updated their response plan to any possible introduction of the infection. Regular reviews are conducted by APHIS, based on experience in other nations confronted with catastrophic diseases and the Agency conducts regular exercises to ensure preparedness.
An important component of the updated response plan will be the use of an effective FMD vaccine. This is an important departure from the conventional stamping-out approach. Obviously APHIS was influenced by the extensive outbreak in the U.K. that commenced in 2018 and resulted in extensive losses in the dairy, beef, pork and sheep industries. During the initial six months of the outbreak, the resources of the Department of Agriculture were overwhelmed. Control was only achieved when the U.K. military were called on to deplete farms and dispose of carcasses, ending the outbreak.
Post-disease reviews clearly indicated that quarantine including restricting movement of animals, products and personnel were critical to limit the spread of infection. FMD is not in itself a fatal disease and animals can recover if provided supportive therapy and care. Ring immunization to establish a barrier against dissemination of virus will be incorporated in any future outbreaks of FMD in the U.K. Epidemiologic monitoring has clearly demonstrated the value of immunization coupled with traditional methods of control. Now that the playbook has been revised for the U.S., it is hoped that a stockpile of FMD vaccine will be available to conduct an extensive immunization program as part of any required response.
Prevention of FMD by rigorous control at points of entry into the U.S. is still the most effective strategy to prevent catastrophic infections such as FMD and African swine fever, requiring the cooperation of trading partners and especially Mexico and Canada. By the same token the USDA and the Customs and Border Control service have a joint responsibility to exclude all exotic diseases.
The concept of using an FMD vaccine as a component of control should be reconsidered with respect to avian influenza. The 2015 outbreak required depletion of over 40 million birds and was a costly exercise for the industry, APHIS and consumers. The probability of introducing HPAI into the U.S. is far greater than FMD given that migratory waterfowl transmit the virus. This is evident in Europe and Asia at the present time. With the general adoption of compartmentalization for breeders and regionalization for production of eggs and poultry meat, ring immunization could be considered to control other than limited outbreaks of HPAI as implemented in Italy with an inactivated DIVA vaccine during the late 1990s.
In 2015, the use of vaccines to control HPAI in the egg industry was essentially vetoed on the grounds that it would seriously impact exports of poultry meat. Given the current situation, applying vaccines to control HPAI among egg production flocks in Iowa should not affect export of leg quarters and feet from southeast states if importing nations accept World Organization for Animal Health (OIE) guidelines. Outbreaks of Exotic Newcastle disease in backyard flocks in southern California, extending over thirty months and the limited outbreak of avian influenza among turkeys in the Carolinas in 2020 indicate a more flexible approach to restricting exports by our trading partners. It is inevitable that HPAI will return to the U.S. poultry industry and accordingly we should not exclude consideration of judicial and appropriate use of vaccines as a component of control.