Avian Flu Outbreak in Dairy Cows: A New Challenge for U.S. Farmers

Earlier this spring, California dairy farmers noticed an unusual drop in milk output in Texas, New Mexico, Idaho, Ohio, Kansas, and Michigan. Weeks later, it was revealed that numerous herds in these states, as well as North Carolina, had been infected with avian influenza, the same strain that has decimated bird populations around the world and demonstrated a disturbing capacity to spread to mammals.

To protect local herds against infection, officials in California and elsewhere have set limitations on cow imports from impacted areas, while the United Areas Department of Agriculture has recommended livestock managers limit cattle movement as much as possible.

Although the US Centers for Disease Control and Prevention feel the current risk to the public is low, the development has left dairy farmers reeling. U.S. dairy cows have never been infected with H5N1 avian flu viruses. X`”Nobody saw this coming,” said Michael Payne, a research and outreach coordinator at UC Davis’ Western Institute of Food Safety and Security.

For years, scientists and health organizations around the world have tracked the virus’s progress.

Since 2021, it has killed hundreds of millions of farmed chickens and infected over 48 species of animals, including humans, as well as an unknown number of wild birds. It has also proven particularly lethal to some communal mammals, like elephant seals and sea lions in South America, as well as confined fur-farmed animals in Europe.

However, outbreaks in dairy cows have come as a surprise.

In addition to the cattle infections, a farmworker in Texas who had direct contact with sick dairy cows became infected, although only showed mild symptoms. This was the second recorded human case in the United States.

Despite the farmworker’s slight condition, the likelihood of further infections concerns some.

“The concerning trend of multiple states reporting cattle infections raises the likelihood of continued human exposure,” said Suresh Kuchipudi, professor and chair of the Infectious Diseases and Microbiology Department at the University of Pittsburgh. “This could amplify the risk of further virus adaptation, potentially facilitating human-to-human transmission.”

Public health activists, wildlife biologists, and epidemiologists believe the cow epidemics have startled farmers and regulators for a variety of reasons. First, while other flu strains have caused sporadic illnesses in cattle in the past, Kuchipudi stated that no other bird virus has ever evolved the potential to spread between cows and other ruminants.

“That was surprising,” he remarked. “Unprecedented.”

Second, no single federal or state agency is in charge of monitoring this disease, which has implications for wildlife, agriculture, and public health. Some experts argue that it is a poor silo-like approach to a virus that affects various government organizations both here and in other countries.

“This is a fundamental problem in our monitoring system, especially when it comes to emerging and zoonotic infections, such as the avian flu,” Kuchipudi added. “This is a public health problem, a wildlife problem, and a domestic animal problem,” for which a one-health solution incorporating all three parts might be extremely beneficial in terms of managing information gathering and transmission.

While it is unknown how the cows contracted the disease, experts believe that if farmers had kept an eye out for sick birds or wildlife and communicated with wildlife agencies and farm bureaus, the infection may have been contained.

California’s Department of Food and Agriculture is now urging farmers to keep an eye out for sick birds and mammals, as well as make efforts to gently remove migrating birds and waterfowl that may come into contact with their herds and prevent them from nesting nearby.

There is also fear that the disease was transmitted by infected poultry litter, which is a mixture of fowl excreta, spilled feed, feathers, and other trash scraped from the floors of industrial chicken and turkey production factories and utilized in cow feed on some farms in the United States. According to Payne of UC Davis, poultry manure in California is handled at high virus-killing temperatures, so there is little worry.

The practice is prohibited in the United Kingdom, the European Union, and Canada, where fears about transmitting bovine spongiform encephalitis (mad cow disease) made such practices appear too dangerous.

Despite worries raised by some experts, California officials say current avian flu monitoring procedures are effective. State Veterinarian Annette Jones stated that she collaborates with numerous state and federal authorities, including the United States Department of Agriculture.

“We have veterinarians and professionals distributed across the state who can conduct initial investigations. And if there is any indication that there may be a human health issue, we also collaborate closely with the California Department of Public Health, which has ties to County Public Health and the CDC,” she explained. “To the outsider, that probably looks like acronym soup, right? But we know as insiders with experience.

Jones and others in the dairy and agricultural sectors believe the public should not be scared or concerned about avian flu-infected livestock. They believe afflicted animals have a moderate reaction and recover rapidly. Also, milk is pasteurized, so if an infected cow’s milk enters the system, the virus is killed.

Others, however, believe the “what’s next” question is the most concerning.

“We want to address what is going on so that we can prevent something worse from happening,” said J. Scott Weese, an Ontario Veterinary College professor and director of the University of Guelph’s Centre for Public Health and Zoonoses. “That something worse is this virus becoming a virus that can be easily transmitted between humans and can cause serious disease.”

Experts say the illness has already defied predictions, from its capacity to infect a wide range of species to its global spread and persistence. Crystal Heath, a Bay Area veterinarian and co-founder of Our Honor, an animal protection organization, believes that its existence on a mammal-based factory farm should prompt increased surveillance and worry.

“You have hundreds, if not thousands of genetically similar animals all living in the same space, standing in each others’ waste and breathing on each other,” Heath said. “Its Shangri-La for an opportunistic virus.”

According to Weese, it is still unclear how widespread the virus is or how long it has been infecting cattle.

The fact that observers detected a decline in milk output in states with infected cattle shows that it may have been there for weeks or months. And if symptoms in cattle and humans were minor enough not to necessitate a visit to a veterinarian or doctor, it might be circulating and having even more chances to evolve, according to Weese, including finding a mammalian host with human and bird flu, allowing it to mix and recombine.

According to Matthew Hayek, an assistant professor of Environmental Studies at New York University’s Department of Environmental Studies, many people are now looking into factory pigs and swine. Pigs are regarded as effective flu-recombination factories — mammalian vessels that combine human and avian flu viruses with potentially fatal ease.

“That’s a problem not just for the sake of our food production,” he went on to say, “but for the sake of our safety as a species.”