by Sally Colby
Between thinking about crop yields, weather and commodity prices, farmers sometimes ponder the unthinkable: the possibility of a foreign disease reaching the U.S.
One such disease is foot-and-mouth disease (FMD), which was in the news in the early 2000s when it hit Great Britain. Throughout that outbreak and to this day, the USDA works tirelessly to ensure that FMD and other disastrous diseases don’t enter America.
Jamie Jonker, vice president of sustainability and scientific affairs for the National Milk Producers Federation (NMPF), has been following advances in a vaccine to protect cattle and other species that can become infected with FMD.
Jonker describes FMD as a highly transmissible disease of dairy cattle, swine and other cloven hooved animals. “The last outbreak in the U.S. was in 1929,” he said. “That means very few people in the U.S. have seen it unless they’ve been somewhere else in the world where there’s been an outbreak.” In addition to the outbreak in Great Britain and in South America in the early 2000s, more recent outbreaks have occurred in Southeast Asia and Africa.
“It’s a disease that is still around the world,” said Jonker. “As we live in a global society, the potential for the transmission of the disease – unintentionally or intentionally – is of concern for livestock producers in the U.S.” Jonker added that there have been numerous changes in how an FMD outbreak would be dealt with in the U.S. since the UK incidence.
“I don’t think we’d find if acceptable to massively slaughter animals,” he said. “That means we have to increase our capability to deal with the disease if an outbreak occurs.”
The good news is that the FMD vaccine bank managed by the USDA is now modernized and much more prepared to deal with an outbreak. “The vaccine bank (for use during an outbreak) is managed by the USDA,” said Jonker. “There are very specific prohibitions about how FMD disease can be researched here in the U.S. and who can store the vaccine.”
One of the most challenging aspects of FMD and manufacturing a suitable vaccine is that while FMD is one virus, there are numerous serotypes. The types that have been circulating in South America are different from those in the Middle East, Southeast Asia and Africa.
“That means we have to be prepared for a variety of serotypes,” said Jonker. “But vaccine technology has continued to advance, and that’s been important in being able to modernize the bank.” Jonker explained that the USDA purchases vaccine antigen, which can be stored longer than the actual vaccine. If the antigen is needed, the USDA works with a vaccine manufacturer to determine the serotype then ramps up vaccine production for use where it’s needed.
Jonker said in the past, the amount of antigen has been limited, so the volume required to immunize animals would not be available if an outbreak occurred in the U.S. The 9.5 million mature dairy cows plus female replacements, 94.8 million beef animals and millions of pigs, sheep and goats would require tens of millions of doses for protection. “Up until this year, the vaccine bank didn’t have the volume for those numbers,” said Jonker. “In the 2018 Farm Bill, there was a special provision to increase U.S. preparedness for foreign animal diseases, including FMD. The bill has specific funding that allowed the USDA in July to announce an agreement to purchase $27 million worth of FMD vaccine. They also announced that it was the first of several purchases over the next few years.”
This funding will greatly expand the capacity of the vaccine bank. Jonker said previously, the vaccine antigen had a shelf life of five years, but the shelf life is now 10 years. “Not only are they purchasing more,” he said, “it will have a longer shelf life so they don’t have to continue to purchase the same serotype as often.”
Should farmers be worried about FMD? Jonker said there’s heightened concern about the disease entering the U.S., partly the result of watching what happened in the UK. The other basis for concern is that around the same time as the UK outbreak, FMD was identified as a bioterrorism agent. “The concern is making sure we have the ability to respond to an intentional or an accidental introduction,” he said. “Sometimes it takes a while for things to happen through governmental processes, and part of that was getting dedicated funding to modernize the vaccine bank.”
Some wild animals are potential vectors for disease transmission, including feral swine. Other cloven hooved animals such as deer can get FMD, and although they may not show signs of disease, they can still transmit it. Vehicles and people who visit the farm including feed trucks, veterinarians, hoof trimmers and nutritionists are potential spreaders of FMD.
“It isn’t just that we now have more vaccine and we’re all set,” said Jonker. “USDA has a disease response plan that considers all the risk factors involved in an FMD outbreak. The USDA plan looks at the scale of the outbreak and how they would respond based on outbreak characteristics.” Part of the ongoing FMD control plan also involves strict inspections at ports of entry, include searching for items that can possibly transmit FMD.
Jonker said that in the event of an outbreak, the response will, ideally, be based on risk and science. First, the serotype must be definitively defined, then there will be a period of time for the manufacturer to take the antigen and put it in vaccine doses. Between identifying an outbreak and vaccine availability, there will be additional control measures such as restrictions on livestock and livestock product movement. “It will be a week or so from the time we know we have an outbreak to the time we have a vaccine,” said Jonker.