Highly pathogenic avian influenza (HPAI) has been a disease of concern for poultry producers for the past several years. While the virus remains a serious threat to poultry producers, farmers who raise other livestock weren’t too concerned until the virus jumped species and infected dairy cattle.
The main characteristic of zoonotic disease such HPAI is potential transmission to other animal species and humans.
Dr. Jonathan Zack, DVM, director of National Preparedness and Incident Coordination, USDA-APHIS, addressed the issue in a recent industry call. Zack said since February 2022, poultry producers and allied industries have been responding to the current HPAI outbreak in domestic poultry. HPAI has been detected in 48 states and in more than 1,164 commercial and backyard poultry flocks.
“The key is that poultry producers and allied industries have been working hard on a long campaign for HPAI in the U.S.,” said Zack. “Unfortunately, this is going to continue with the threat of HPAI virus in domestic waterfowl here in North America and throughout the world.”
With widespread HPAI and its recent jump to dairy cattle, the virus isn’t going away soon. In the interest of animal and human health, USDA-ARS is testing HPAI vaccines for both poultry and cattle.
Zack said there’s a lot of difference in using vaccines to manage disease in poultry and dairy cattle.
“Within poultry, different groups of animals or commodity sectors such as turkeys, chicken layers, chicken broilers or backyard poultry are all significant commodities,” he said. “Vaccination of poultry is very complicated in terms of how to effectively vaccinate the poultry at the hatchery and [administer] the secondary booster vaccine necessary. I think for any emergency use of vaccine, whether it’s for dairy cattle or poultry, we need to look at the big picture where that isn’t a unilateral decision by APHIS. There are potential consequences across the board for intrastate commerce, interstate commerce and international trade.”
The consensus in the poultry industry is that an HPAI “stamping out” program is necessary. Zack believes it’s important for industry sectors to work together to discuss vaccination scenarios and policies, to share information about what might work technically and what might work for a particular business or commodity and the impact on trade.
Zack discussed the implications for trading partners if there’s a vaccine program in the U.S. “Is it safe and effective, and how would you use it in any given commodity group?” he said. “In the U.S., we’ve been able to successfully respond to HPAI in domestic poultry without emergency use of vaccine. We’re trying to understand what other countries have done in terms of their vaccine and research and their surveillance of vaccinated flocks.”
Considerations for a vaccine program include understanding the vaccines available, whether programs are cost-effective and if a flock is vaccinated, how will it be monitored? What will producers do if a suspected wild HN strain is introduced on top of the vaccine? Will producers maintain a stamping out/zero tolerance approach for detection of avian influenza, even in a vaccinated flock?
In addition to HPAI, Zack pointed out that a major concern for years has been foot-and-mouth disease (FMD) entering the U.S. Ongoing industry efforts include establishing the new vaccine bank and determining how an FMD vaccine would be used in an outbreak.
“For any trans-boundary disease, exclusion is very important,” said Zack. “The key is determining how we’re prepared to respond if exclusion fails.”
While the U.S. was unprepared for HPAI in dairy cattle, Zack believes that six to 12 months of working together to prepare for such an outbreak would have been better for dairy farmers. Despite the surprise factor, Zack said dairy farmers and industry have worked well together to manage the issue.
“Any successful animal disease program or response or emergency effort has to include producers, industry groups, the National Animal Health Laboratory Network (NAHLN) and state animal health officials,” said Zack. “The more we can come to a consensus for a response, the better off we are. We’re for any opportunities to collaborate on this current and future endeavors.”
Dr. Jamie Jonker, chief science officer for National Milk Producers Federation (NMPF), agreed that the dairy industry was completely surprised when HPAI was discovered in dairy cattle. “It wasn’t on our radar until March 25,” he said. “When we started seeing herds with mystery illness in the Texas panhandle and New Mexico, we were ruling out everything else. Thanks to the work of laboratories, we found out it was H5N1 – nothing we would have worked to prepare for. It’s a novel, emerging viral issue in dairy cows.”
Jonker noted that about 145 dairy farms have been affected by HPAI. “On individual farms, there’s a very large impact over a several week period,” he said, listing loss of production in clinically infected cows and the cost of treating symptoms. “It’s a very resource-intensive time on the farm with workers and family members working around the clock in a 30-day, intense process.”
Dr. Doug Ensley, DVM, director of Veterinary Public Health for Boehringer Ingelheim Animal Health USA, also spoke to the issue of vaccines. Boehringer Ingelheim has been involved with poultry influenza globally and is one of the companies that submitted information for dairy cattle vaccination. Ensley said the company is working closely with USDA to look for opportunities to test and develop innovative products.
The National Animal Disease Preparedness & Response Program (NADPRP), along with the National Animal Vaccine & Veterinary Countermeasures Bank, was established by the 2018 Farm Bill and allows the U.S. to increase its ability to stockpile veterinary countermeasures to protect American livestock from foreign animal diseases.
“The bank isn’t really vaccines,” said Ensley. “It’s antigens, because we know that most vaccines have a very short expiration date. The antigen has a long-term expiration date. It’s frozen and allows us, if FMD comes to this country, to supply doses of vaccine very quickly. We’ve seen how important speed is to response to disease.”
Ensley explained that vaccine companies work with vaccine bank managers and USDA to determine where strains of a virus are occurring and determine the risk and which strains should be put in the bank.
“We don’t have cross-protection against strains,” he said, “but having the right supply in the bank is important.” Logistics are critical to ensure a timely process.
“USDA does an outstanding job of monitoring, but companies and producer groups bring more to the table,” said Ensley. “Boehringer is always looking for ‘what works.’ There’s better technology out there – what will make it better for the producer? The easier and better the technology, the more compliant producers will be.”
by Sally Colby
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