With the fall wild bird migration just around the corner, dairy farms are being urged to get biosecurity plans in place to prevent an outbreak of highly pathogenic avian influenza.

The HPAI strain that has so far affected 192 dairy farms in 13 states has not been found in the Northeast or mid-Atlantic yet. But Dr. Alex Hamberg, Pennsylvania's state veterinarian, says better health surveillance of dairy farms will be needed to stamp out a possible outbreak.

“We need more participation, and we're working with various processors and dairy farmers to build that additional surveillance, and address some of the logistical concerns with getting that done and doing a lot of outreach to get the data we need," he says.

Push for biosecurity

At last week’s Ag Progress Days, representatives from the state’s department of agriculture handed out biosecurity worksheets developed by the Farmers Assuring Responsible Management (FARM) program that has recently been modified for dairy farms.

The 20-page document includes a self-assessment of animals and animal movements, as well as biosecurity controls for people visiting. Only 20 dairy farms have these plans on file with the state, says Seth Confer, the department’s biosecurity program specialist.

But having one in place is crucial, he says, because it will allow a quarantined farm that has tested positive for HPAI to get a movement permit to continue shipping milk to the processor.  

"Pennsylvania is very unique in that we have so many farms that have dairy and swine, dairy and poultry, poultry and swine, all of it. So, obviously the biggest thing right now is dairies because HPAI has been found in more dairy farms across the country," Confer says.

"We're finding it difficult to get stakeholder buy in, if you will. A lot of people are under the impression that it's not in Pennsylvania that we know of, so why do I need to care? One of our biggest pushes is to get people to care," he adds.  

Unique strain

While wild and migratory birds are known carriers of HPAI, Hamberg says the strain that has affected dairy cattle — H5N1 2.3.4.4B substrain B3.13 — has not been found in wild and migratory birds in the Atlantic Flyway, the major north-south flyway for migratory birds that played a major role in the spread of HPAI in poultry in 2022 and 2023.

Based on available data, Hamberg thinks the substrain that caused the first HPAI cases in dairy was mostly likely a mutation of the original H5N1 virus of which the original host was most likely wild birds.

He notes that this H5N1 strain has been circulating around the world for 30 years with occasional spillover events to mammals. But up to now, it has not been very good at spreading quickly. For example, the human cases of HPAI have come from people in direct contact with sick animals with no community spread reported.

Preventing the spread

Unlike HPAI in commercial poultry, which spreads because of wild birds encountering commercial flocks, this substrain spreads among people coming in contact with sick animals; by contaminated farm equipment and tools; and from cows that are infected but not showing symptoms.  

"That's a good thing, because we can combat that with biosecurity,” Hamberg says. “It also means that there hasn't been any detection of a native, natural wildlife reservoir for this virus. As long as it hasn't developed a wildlife reservoir, there is still a chance we can stamp it out.”

Cornell recommends the following steps to protect dairies:

“I still think our movement controls are good as long as people are following the rules and we're picking up animals before they get here,” Hamberg says. “If it gets into migrating wild birds, then it becomes a different story. Even if it's not in our flyway, many of the birds will congregate in their summer and winter grounds, and then they'll spread back out into the flyways to make the journey to the next stop, so they do have the ability to move the virus to different flyways.

“As long as it stays out of our flyways, I think we're in pretty good shape with our movement controls. What we need, though, is to get more surveillance data so that we can be assured that if it does come here, we can detect it early.”