Scope of avian flu spread in cows is still not known, worrying health experts

Reliance on individual dairy farmers to help track the spread of avian flu is leaving the federal government without the data necessary to understand — and slow — the virus’ spread in the U.S.

The biggest challenge for the federal response, agriculture and public health officials told POLITICO, is that the more the virus spreads among dairy cows, the more opportunity it has to mutate and become easier to jump to additional humans. The number of documented infected dairy herds in recent weeks has risen rapidly — and several other states have confirmed initial infections in cows.

But many dairy farmers are declining to test their cows, leaving the nation vulnerable to a situation in which federal officials won’t have adequate warning if the virus evolves and poses a greater risk of infection to people.

“The longer this is prevalent in animal farms and livestock operations across the state, the greater the opportunity is for future mutations in animals or human risks in different ways going forward,” said Tim Boring, who heads the Department of Agriculture and Rural Development in Michigan, a state with two confirmed human cases to date as it deals with a major bird flu outbreak among poultry and now dairy herds.

The federal response is largely focusing on voluntary efforts by farmers to help track and contain the outbreak. But many farms still have not signed up for USDA efforts to boost surveillance and testing for the virus. To date, 94 herds across 12 states have tested positive for bird flu, but the testing has covered a mere fraction of the nation’s nine million dairy cattle. Only about 45 exposed and symptomatic humans have been tested for avian flu, CDC Principal Deputy Director Nirav Shah said in a Thursday briefing with reporters.

Mark Lyons, a senior USDA animal health official, said federal officials are “still working closely to understand the breadth” of the bird flu outbreak in the nation’s dairy herds.

While the risk to the public remains low, the CDC is focusing on preventing cases in populations at higher risk of infection. Given the extent of spread among dairy cows, additional human cases in farmers and dairy workers “would not be surprising,” according to CDC spokesperson Rosa Norman.

“Continued comprehensive surveillance in wild birds, poultry, mammals and people worldwide are critical to determine the public health risk, along with ongoing preparedness efforts,” the spokesperson said. “We are taking a number of measures to keep up testing and sequencing of influenza viruses over the summer to help increase surveillance.”

Jerome Adams, former surgeon general under President Donald Trump, said more testing is needed to understand how widespread avian influenza is — a threat he described as rapidly growing and potentially catastrophic despite the limited human infections detected to date. But farmers and workers must be reassured that they will not face legal penalties by allowing government officials onto farms and there should be financial incentives to participate in testing, he added.

“We failed — through two administrations — to develop and implement an effective surveillance strategy with Covid, and we are repeating the same mistakes with [this virus],” Adams said. “Farmers are reticent to test for many reasons. Fear of financial harm is a major factor.”

Since April, more than 15,000 animal samples have been tested, with more than 4,300 under a federal order requiring dairy cow testing before animals are moved across state lines, according to USDA data.

Deborah Birx, former Trump administration coronavirus response coordinator, said it is essential to know whether the baseline incidence of infections among dairy cows and humans is changing so the government can prepare a response.

“It’s not about pointing fingers, it’s not about whether their workers are documented, it’s about knowing where we are and how much this is spreading in humans, and how much is spreading in cows,” Birx said. Allowing voluntary anonymous testing and taking steps to allay fears that farms could be shut down is critical to get that buy-in, she added.

A new effort by the CDC aims to ensure that clinical laboratories send samples from people with suspected novel influenza infections like avian flu to state health laboratories for further testing. The guidelines call for the CDC to be alerted of specimens that test positive for such viruses or if unsubtyped results are obtained.

“We have indicated to states that the threshold for testing somebody is exceedingly low if they do happen to detect somebody who has been exposed and who would like to be tested,” Shah told reporters. “We're open to doing that, very much so.”

HHS Secretary Xavier Becerra urged state leaders at the Western Governors’ Association Annual Meeting to help increase monitoring for avian influenza.

“That includes reaching out to dairy farmers in your states to confirm they are taking steps to protect workers — and encouraging those farms to test their cows or their milk so we know quickly if a herd is positive,” Becerra said earlier this week according to prepared remarks.

Although federal funds have been allocated, no farms have enrolled in voluntary on-site milk testing, according to the USDA. Fewer than a dozen farms have applied for separate financial aid in exchange for boosting biosecurity measures to help contain the virus. Meanwhile, federal rulemaking is delaying the rollout of compensation for farmers who have lost or had to kill cows because of the disease.

That’s a problem because the scope of financial support for dairy farmers to date has been “peanuts,” according to Michael Mina, chief science officer at telehealth company eMed and a mass-testing advocate during the Covid-19 pandemic. With the virus spread across many herds across the country, strengthening sequencing efforts to understand if a mutation that warrants aggressive action toward a particular farm is critical.

“We actually did have a period of time where there was a possibility to contain this had we taken very aggressive fast action,” Mina said. “Those days are done. It’s big and you can’t just squash it.”

Michael Osterholm, an epidemiologist and director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said that even if every cow in the U.S. is tested daily, it does not guarantee that a mutation won’t occur that starts a new pandemic.

“What I would like to know is in terms of transmission issues, is how many of these current farms that are turning up positive can trace back cattle movement to the original outbreak farms,” Osterholm said. “If that can't happen, it greatly complicates how you try to stop ongoing transmission in dairy cattle.”

Michigan, which is dealing with a major bird flu outbreak among poultry and now dairy herds, is undertaking an “aggressive” response effort, Boring said. There have been no confirmed avian flu fatalities in the U.S.

In recent days, Wyoming, Minnesota and Iowa have announced their first confirmed avian influenza cases in dairy herds, underscoring many agriculture officials’ fears that the virus is present in wide swaths of the country but just hasn’t yet been detected.

Shah deferred to USDA when asked how much dairy cow surveillance testing the CDC believes is necessary on a call with reporters on Thursday. State agriculture officials and some farmers pushed back on an early CDC effort to deploy federal public health officials on farms across the country to better track and contain the virus.

So far, 11 farms have enrolled in financial support programs the USDA announced May 10 to help bolster biosecurity measures to contain the virus, according to USDA spokesperson Allan Rodriguez. No farms have enrolled in a separate voluntary testing pilot program to monitor virus levels in milk in dairy herds, though there’s been interest in the effort and the USDA “expects the number of participating producers to increase in the weeks ahead.” The department is talking with at least 20 states about participation in the pilot program.

“USDA continues to ramp up outreach and leverage every tool available to raise awareness of these new resources,” Rodriguez added.

Dr. Jamie Jonker, the chief science officer at the National Milk Producers Federation, said that “any widespread disruption to an industry is going to encounter a wide variety of responses and questions.”

“Only three months into H5N1 in dairy cows, testing is identifying affected farms, and dairy farmers are taking action in response,” Jonker said. “With USDA programs in effect for just over one month, farmers are working with USDA to make them effective, even as details of those programs are still being worked out,” he added, noting dairy farmers are doing what they can both to understand the H5N1 situation and work effectively to address it.

Boring said Michigan state officials are working to head off a potentially devastating blow to the dairy industry and to try to keep the virus from spreading to more humans. While the U.S. has responded to bird flu outbreaks in the poultry industry for decades, the outbreak among dairy cows is a new and vastly different challenge. Boring acknowledged state officials are still flying somewhat blind in their response after the virus was first detected in dairy cows in Texas in late March.

“It's a tough situation. There's a lot that we still don't know. We're learning more every day,” Boring said.

“So oftentimes, we're working with a bit of incomplete information,” he added.

Boring said he believes several Michigan farms have reached out to the USDA for more information about the financial aid the department announced last month as a way to contain the virus, but he didn’t know whether any farmers have applied for the USDA money.

Producers in his state are chiefly watching the USDA’s expected rollout of specific emergency assistance funding for livestock losses in the coming weeks. Agriculture officials in blue and red states are pressing the USDA to make that move as generous as possible to offset the growing economic toll of the virus, while working to contain the spread.

But that effort is “continuing to go through the [federal rulemaking process],” according to USDA, signaling that a full rollout could take months. It’s also unclear how many infected cows in the U.S. are dying from bird flu or being killed due to a drop in milk production.

Boring confirmed “there have been instances of cow fatalities associated with this” in Michigan, but he didn’t know how many infected cows have been killed, or culled, in his state.

He suggested culling is still used in “rare instances” for infected cows that contract other diseases and wasn’t aware of any mass culling.

“We're concerned about the spread of this into other populations, whether it's swine, or whether it's directly to humans,” Boring said.

Still, public health experts like Osterholm who have been monitoring avian influenza for decades caution that no one knows what the future holds.

“I've been dealing with this virus since 2003 and on multiple occasions, thought, well, this is it, it's going to go, and then it didn’t,” Osterholm said. “That doesn't mean it won't go now, but it also means be careful, because, in fact, what we're seeing happen may not be indicative that we're going to see a major antigenic change in the virus.”