California dairies are scrambling to protect herds from bird flu

Earlier this spring, California dairy farmers noticed a puzzling decline in milk production in Texas, New Mexico, Idaho, Ohio, Kansas and Michigan. Weeks later, news emerged that several flocks in these states, as well as North Carolina, had been diagnosed with avian influenza — the same strain that has devastated bird populations around the world and demonstrated an alarming ability to jump to mammals.

In an effort to prevent domestic herds from becoming infected, officials in California and elsewhere have imposed restrictions on livestock imports from affected states, while the USDA has urged livestock managers to reduce livestock movement as much as possible.

Although the U.S. Centers for Disease Control and Prevention believes the current risk to the general public is low, this development has left dairy farmers reeling. Never before have dairy cows in the United States been infected with the H5N1 avian influenza virus.

“Nobody expected this to happen,” said Michael Payne, a researcher and outreach coordinator at the Western Institute for Food Safety and Security at the University of California, Davis.

Scientists and health agencies around the world have been tracking the spread of the virus for years.

Since 2021, the virus has killed hundreds of millions of farm poultry and infected more than 48 species of mammals — including humans — as well as untold numbers of wild birds. It has also proven particularly deadly among some communal mammals, such as elephant seals and sea lions in South America, as well as caged animals in Europe.

However, the outbreak among dairy cows came as a rude shock.

In addition to the cattle infections, a farm worker in Texas who had close contact with infected dairy cows was also infected, but experienced only mild symptoms. This was the second known human case in the United States.

Although the agricultural worker's illness is mild, the possibility of continued infection worries some.

“The alarming trend of cases being reported in livestock in several states raises the possibility of continued human exposure to the virus,” said Suresh Kuchipudi, professor and chair of the Department of Infectious Diseases and Microbiology at the University of Pittsburgh. “This could increase the risk of further adaptation to the virus, which may facilitate human-to-human transmission.”

Public health advocates, wildlife biologists and epidemiologists say there are several reasons why livestock outbreaks caught farmers and officials by surprise.

First, although sporadic infections of livestock via other strains of influenza have occurred in the past, no other avian influenza has evolved the ability to pass between cows and other ruminants, Kochipudi said.

“It was surprising,” he said. “Absolutely unprecedented.”

Second, there is no single federal or state agency responsible for monitoring this disease, which affects wildlife, agriculture, and public health. Some experts say it's a flawed, silo-like approach to the virus that has many government agencies here and in other states concerned.

“This is a fundamental problem in our surveillance system, especially when it comes to emerging diseases and zoonoses, such as avian influenza,” Kochipudi said. “It's a public health problem, a wildlife problem, and also a domestic animal problem,” in which the One Health solution – which includes all three elements – can help manage information gathering and communications.

For example, while it remains unclear how cows became ill, experts say that if farmers had been on the lookout for sick birds or wildlife and communicated with their wildlife agencies and farm bureaus, the infection may have been contained.

The California Department of Food and Agriculture is now asking farmers to be on the lookout for sick birds and mammals, take steps to remove migratory birds and waterfowl that could come into contact with their flocks, and prevent them from nesting nearby.

There are also concerns about the disease being transmitted through infected poultry litter — a mixture of poultry litter, spilled feed, feathers and other waste scraped from the floors of industrial chicken and turkey production plants — that is used in the United States. In livestock feed on some farms. In California, poultry waste is processed at high temperatures that kill viruses, so that's unlikely to be a concern, UC Davis' Payne said.

The practice is banned in the UK, EU and Canada, where fears of the spread of bovine spongiform encephalitis – mad cow disease – have made such practices seem too risky.

Despite concerns expressed by some experts, California officials say current efforts to monitor bird flu are effective.

State veterinarian Annette Jones said she works seamlessly with several state and federal agencies, such as the U.S. Department of Agriculture.

“We have veterinarians and experts spread across the state who can do those initial investigations. “If there is any inkling that there may be a human health issue, we also work very closely with the California Department of Public Health, which has links with county public health and the CDC,” she said. “To an outsider, this probably sounds like shortcut soup, right? But to an experienced insider, we know.”

Jones and others in the dairy and agricultural sector say there is no reason for the public to be alarmed or concerned when it comes to livestock infected with bird flu.

They say infected cows seem to have a mild reaction and improve quickly. The milk is also pasteurized, so if milk from an infected cow enters the system, the virus will be killed.

However, others say the question “what's next” is most troubling.

“We want to address what's happening so we can prevent something worse from happening,” said J. Scott Weese, a professor at the Ontario College of Veterinary Medicine and director of the Center for Public Health and Zoonoses at the University of Guelph. “What is even worse is that this virus will mutate into a virus that can be easily transmitted between humans and can cause serious illness.”

Experts say the disease has already defied all expectations, from its ability to infect a variety of species, to its international spread and duration. That would make his appearance on a mammal-based factory farm cause for increased surveillance and concern, said Crystal Heath, a Bay Area veterinarian and co-founder of Our Honor, an animal welfare organization.

“We have hundreds, if not thousands of genetically similar animals, all living in the same place, standing in each other's waste and breathing on each other,” Heath said. “It's the Shangri-La of an opportunistic virus.”

It's still unclear how widespread the virus is, or how long it has infected livestock, Weese said.

The fact that observers have noticed a decline in milk production in states now known to have infected herds suggests to some that it may have been present for weeks or months. If symptoms are mild enough in livestock and humans to not warrant a visit to a veterinarian or doctor, the disease could spread and have a greater chance of evolving, including finding a mammalian host infected with human influenza and avian influenza, providing an opportunity to evolve, Weese said. Mix and recombine.

That's why many are now turning to factory pigs, said Matthew Hayek, an assistant professor of environmental studies at New York University in the Department of Environmental Studies. Pigs are alarmingly effective as influenza recombination factories — mammalian vessels that mix human and avian influenza viruses with deadly ease.

“This is a problem not only for our food production, but for our safety as a species,” he said.