Bird Flu Experts Express Concern Over Food Safety Amid Outbreak

In a press briefing, Johns Hopkins Bloomberg School of Public Health experts said the H5N1 dairy cattle outbreak could pose specific food safety risks to humans and pets.

According to the Centers for Disease Control and Prevention (CDC), H5N1 bird flu has affected over 90,000,000 poultry and over 40 dairy cattle herds in nine states. Only two human cases of bird flu have been confirmed, one related to exposure to infected poultry in 2022 and another reported this year in a person exposed to infected dairy cattle in Texas.

No human-to-human transmission of H5N1 has been reported, and the risks to humans remain low.

However, recently, the safety of milk and meat from infected cattle came into question after testing showed that one in five samples of store-bought milk contained fragments of H5N1.

Still, the U.S. Food and Drug Administration (FDA) says that as of May 10, testing of 297 retail dairy samples showed no viable virus present. The agency says any H5N1 present in raw milk is destroyed by pasteurization.

In addition, retail meat samples tested by the U.S. Department of Agriculture (USDA) were negative for bird flu.

However, in a May 15 Johns Hopkins Bloomberg School of Public Health media briefing, experts in microbiology and environmental health told reporters that while H5N1 risks to humans remain low, there is concern over the potential for bird flu to be present in specific food products, pet food, and drinking water.

What are the concerns over the presence of H5N1 in food?

Andrew Pekosz, Ph.D., professor and vice chair of the W. Harry Feinstone Department of Molecular Microbiology and Immunology at Johns Hopkins, said there are documented cases of human infections from eating undercooked poultry products contaminated with H5N1 or encountering infected birds during the slaughtering process.

"This process of coming into exposure with infected material and consuming it is one that has been shown to represent a very high risk of infection with H5N1 viruses for a number of years now," Pekosz adds.

Meghan Davis, Ph.D., an associate professor in the Department of Environmental Health and Engineering at Johns Hopkins said that pasteurized milk and meats handled according to meat safety recommendations are generally safe.

According to Davis, raw milk in pet food is also worrisome, not only for the possible bird flu risks for pets but also for humans.

"Feeding pets raw milk could be very problematic given that we know on dairy farms that cats on the farm that have been consuming the raw milk have been getting very sick with neurologic [symptoms], respiratory disease, and high mortality," Davis explained.

Davis says that if H5N1 were to infect pets, not only would that be a concern in terms of the virus and its potential to mutate into something more adaptive to humans, but it also could expose people in ways that differ from exposures related to meat processing plants or dairy farms.

Could other food products contain bird flu?

While commercial milk and beef have undergone testing for the presence of bird flu, Davis said that dairy cow manure should also be tested to understand the potential risks of the virus contaminating crops fertilized with cattle manure.

According to Davis, exposure assessments "should include testing of manure from dairy cows to see if they might be infectious given that we recognize that a lot of these manures are part liquid, and this may be sprayed onto the crop fields or onto fields that are adjacent to places where you might have raw crops or fruit products that could potentially become contaminated."

Davis noted that H5N1 is an envelope virus, so they expect it to become inactivated in the environment over time.

"But we don't know the dimensions of that, and without knowing that, it's hard to really understand all the different routes of exposure not only within the farm but from the farm into surrounding areas," Davis added.

Is bird flu in drinking water?

Recent testing revealed that H5N1 markers were present in wastewater, especially in areas with a high number of confirmed bird flu cases in cattle. However, whether H5N1 could be present in the drinking water supply is unclear.

"We don't yet know the survivability of the virus in this particular case under those conditions," Davis explained. "What we do recognize is that one of the ways that wild birds can get infected is through water."

Still, Pekosz noted that chlorination should inactivate any virus in public water treatment systems.

"I think in terms of the water that all of us drink from our homes, there's a high level of assurance that the water will be safe," Pekosz said.

The latest on bird flu vaccines

While the risk of bird flu transmission between humans is currently low, Pekosz is confident that the United States would have a vaccine to combat the disease if it were to happen.

"The U.S. government and other governments have tested and made stockpiles of certain avian influenza viruses and [are] taking them through the first steps of putting them into the vaccine production pathway," Pekosz said. "So, certainly, there is at least one H5N1 vaccine candidate that is essentially ready to be moved to manufacturers to produce large amounts of virus should the need be present."

"We've now got a lot of experience in terms of using those vaccines in humans," Pekosz explained. "So, I think that we're much better prepared to react and respond to a potential H5N1 pandemic than perhaps we were against COVID-19 because we've had several years to […] think about ways that we could speed up that process and get better prepared to deal with it."