As dairy and poultry farmers work to limit losses related to avian flu, they are learning the virus can be transmitted in a wide variety of ways.

Vectors can include, for example, wild waterfowl water contaminating by swimming in dairy farms’ lagoons. 

Changes in farm practices such as stopping the pumping of water that might be contaminated by the virus into dairies for cleaning could save livestock and poultry producers money and improve the reputations of products and facilities, experts say.

“The risk factor increases with every point of contact between people and infected animals. It also increases with every point of contact between infected birds and dairy cows,” said Maurice Pitesky, associate professor of veterinary medicine at the University of California, Davis. 

Maurice Pitesky.jpegMaurice Pitesky | Photo by Don Preisler

Pitesky, who is also an associate specialist in cooperative extension for the University of California, said the virus can be spread by contact with mud or dirt. Individuals who do not wear protective gear or fail to change their clothes and shoes before entering a poultry or dairy facility could be vectors. 

“Say an active hunter or a hiker previously observing wild birds in the wetlands walked into a dairy or poultry facility without taking any precautionary measures, like wearing foot coverings and spraying their shoes. This would increase the risk for the facility. This is ultimately why these facilities go to great lengths to prevent this type of scenario,” said Pitesky.

James Roth, director of Iowa State University’s Center for Food Security and Public Health, said the virus in lactating cattle is extremely similar to the one in commercial poultry. Currently the virus is only known to infect the mammary gland of lactating cows, not young or male cattle. 

Cows produce an extremely high amount of the virus in the milk. USDA is addressing the spread of the virus by requiring the testing of lactating cows before movement between states and state rules that prohibit the movement of cattle from affected dairies in the same state. 

Roth said consumption of pasteurized milk is not a public health concern because the pasteurization process kills the virus.  FDA tests have indicated there are fragments of avian flu virus in milk products in grocery stores in areas with affected cows, but the virus is dead and polymerase chain reaction tests used to detect the virus are extremely sensitive.

"Currently people are not easily susceptible to the virus. Biosecurity measures such as wearing disposable gloves, eye protection, and face masks in milking parlors are helpful. In hot, wet environments like milking parlors, typical face masks become ineffective. Yet even without masks, we’ve only seen one case of a person contracting the avian flu virus in a dairy. That person had mild infection and recovered,” said Roth.

Roth added the virus is highly pathogenic in poultry because it kills 90% of birds. The biggest problem for dairy facilities is a temporary lower production, with a few cows potentially not returning to full production. 

Researchers at universities and vaccine companies are working on an avian flu vaccine for cattle. Once developed, the vaccine would need to be approved through USDA’s process, manufactured, and distributed.

Researchers at Iowa State University and other institutions are also looking at testing bulk milk samples as a way to monitor herds. Once developed, the method must be validated, which takes time. 

"Right now, with the virus present in lactating cows in nine states, facilities should abide by biosecurity measures that focus on milk. The biosecurity measures for poultry are working OK, though not perfectly. Biosecurity is inconvenient and expensive, and has to be done every day by everyone all the time,” said Roth. 

Concern regarding activists and poultry 

An April report by the California Department of Food and Agriculture and USDA suggests activists who entered California poultry facilities in Sonoma County could have spread the virus that required the farms to euthanize thousands of birds. 

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“However, it should be acknowledged that high-pathogenic avian flu had been in wild bird populations for some time preceding that in the state and region. This makes it harder to tie the incidents to the losses. The timing of the incidents and the losses line up. Unfortunately, unless swabs of the activists’ clothing and shoes were taken, it will likely be difficult to definitively prove this scenario. The idea would be to see if they were carrying the strains that the birds at the facilities suffered,” said Pitesky.

Without such evidence, poultry facilities might find it difficult to prove a connection between the activists and euthanized animals in court. 

Cassie King, a spokesperson for Direct Action Everywhere (DxE), the organization associated with 2023 activism efforts at farms in Sonoma and Merced counties, said the CDFA and USDA report focuses on violations of biosecurity protocols by the Sonoma County poultry facilities during the period connected with the 2023 avian flu outbreak.

King said the violations included the sharing of personnel and equipment. 

She said DxE’s biosecurity measures for its team of “investigators” go above and beyond industry standards and DxE’s biosecurity protocols have been veterinarian-approved. Those measures include staying away from poultry, waterfowl, and other birds for at least seven days before entering a facility, she said.

Meanwhile, poultry farms can make progress in limiting the spread of avian flu by adding and improving biosecurity measures with a focus on operational and physical biosecurity, experts say. Such measures include asking employees and visitors about contacts with dairy farms on biosecurity forms.

“We still need to take other steps to limit exposure," said Pitesky. "This virus can move as an aerosol. Dairy and poultry farms should also be using a new generation of remote sensing tools to better understand what is going outside their barns with respect to waterfowl.

"This type of outward-facing biosecurity needs to be integrated toward traditional biosecurity efforts which focus on the actual barns and their physical and operational biosecurity. This can help them make daily predictions regarding wild waterfowl and raptors and other types of risks for a facility."

Fatigue regarding precautionary measures is related to COVID 

The public’s weariness of messaging and the politicization of terms such as “biosecurity” and “quarantine” contribute to a lack of public interest in understanding and preventing avian flu, said Peter Chin-Hong, professor in the University of California, San Francisco’s health division of infectious diseases. 

“Another issue is that avian flu is like COVID-19 in that it also negatively affects respiratory health. Consequently, people don’t want to talk about or hear about avian flu,” said Chin-Hong. 

The good news is that avian flu is not easily transmitted person-to-person. A person may be able to contract avian flu from coming into contact with sick birds or cows. There is currently no evidence that a person who consumed eggs, dairy products, or meat from a sick animal could contract avian flu. Chin-Hong said individuals ingesting raw milk and unpasteurized cheese from sick cows are at a higher risk. 

 “Viruses can mutate, so we are observing who contracts avian flu and how. Still, even if more people start contracting avian flu, we’re ahead of the game compared to COVID,” said Chin-Hong.

Identifying the parties who are most likely to be affected is critical to slowing and stopping the spread of the virus. 

“In this case, that group is farmworkers. They’re like the first responders or essential workers such as nurses during COVID. Right now, we need more funding and effort to educate these workers,” said Chin-Hong. 

Avian flu-specific personal protective equipment for dairy workers includes N95 masks and goggles and visors to protect the eyes. 

“Providing access to care for people who get sick is important. The farmworkers need that care to recover. The community needs to offer this care, so farmworkers do not overwhelm the healthcare system,” said Chin-Hong. 

Correction: An earlier version incorrectly described the findings of a California Department of Food and Agriculture report as to the possible role of activists in spreading the virus. The report only discussed the role of activists in Sonoma County.

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