California dairies scramble to guard herds against bird flu

Earlier this spring, California dairy farmers noted surprising declines in milk production in Texas, New Mexico, Idaho, Ohio, Kansas and Michigan. A few weeks later, news broke that several flocks in those states, as well as North Carolina, had been diagnosed with avian flu – the same strain that has devastated bird populations across the world and has shown a troubling ability to spread to mammals.

In an effort to prevent infection of local herds, authorities in California and elsewhere have placed restrictions on livestock imports from affected states, while the U.S. Department of Agriculture has urged ranchers to minimize livestock movements as much as possible.

Although the U.S. Centers for Disease Control and Prevention estimates the current risk to the general public to be low, this development has shaken dairy producers. Never before have American dairy cows been infected with the H5N1 avian flu virus.

“No one saw this coming,” said Michael Payne, a researcher and outreach coordinator at UC Davis’ Western Institute of Food Safety and Security.

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

Since 2021, it has killed hundreds of millions of farmed poultry and infected more than 48 species of mammals – including humans – as well as countless numbers of wild birds. It has also been particularly deadly in some community mammals, such as elephant seals and sea lions in South America, as well as in caged farm animals in Europe.

Nevertheless, the outbreaks among dairy cows came as a rude shock.

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

Despite the mildness of this farm worker’s illness, the prospect of new infections worries some.

“The concerning trend of multiple states reporting bovine infections increases the likelihood of continued human exposure,” said Suresh Kuchipudi, professor and chair of the department of infectious diseases and microbiology at the University of Pittsburgh. “This could amplify the risk of further adaptation of the virus, potentially facilitating human-to-human transmission. »

Public health advocates, wildlife biologists and epidemiologists say the cattle outbreaks have surprised farmers and authorities for several reasons.

First, although there have been sporadic infections of cattle with other flu strains in the past, no other avian flu has ever evolved the ability to transmit between cows and other ruminants, Kuchipudi said .

“It was surprising,” he said. “Totally unprecedented. »

And second: There is no single federal or state agency charged with tracking this disease – a disease that affects wildlife, agriculture and public health. Some experts say it’s a flawed silo approach to a virus that involves multiple government agencies here and in other countries.

“This is a fundamental problem in our surveillance system, especially when it comes to emerging and zoonotic infections, such as avian influenza,” Kuchipudi said. “This is a public health problem, a wildlife problem and also a domestic animal problem,” for which a “one health” solution – in which all three elements are included – could really help in terms of managing information gathering and communication.

For example, although it is still unclear how the cows contracted the disease, whether farmers had been on the lookout for sick birds or wildlife and contacted wildlife agencies and their farm offices, the infection could have been contained, experts say.

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

There are also fears that the disease may have been transmitted through infected poultry droppings – a mixture of poultry droppings, spilled feed, feathers and other waste scraped from the floors of industrial chicken production plants and of turkeys – which in the United States are used. in livestock feed on some farms. Payne of UC Davis said that in California, poultry waste is processed at high temperatures that kill viruses, so this is unlikely to be a problem.

The practice is banned in the United Kingdom, the European Union and Canada, where fears of the spread of bovine spongiform encephalitis – mad cow disease – have made the practices seem too risky.

Despite concerns expressed by some experts, California officials say existing bird flu surveillance efforts are effective.

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

“We have veterinarians and experts located across the state who can conduct these initial investigations. And if there is a suspicion that there might be a human health issue, we also work very closely with the California Department of Public Health, which has ties to county public health and the CDC,” she declared. “To an outsider, it probably looks like a soup of acronyms, right? But for an experienced person, we know.

Jones and others in the dairy and agriculture industry say there is no reason for the public to be alarmed or concerned when it comes to cattle infected with avian flu.

They say infected cows appear to have a mild reaction and recover quickly. Additionally, milk is pasteurized, so if infected cow’s milk entered the system, the virus would be killed.

Still others say it is the question of “what’s next” that is of most concern.

“We want to respond to what’s happening to prevent something worse from happening,” said J. Scott Weese, a professor at the Ontario Veterinary College and director of the Center for Public Health and Zoonotic Diseases. University of Guelph. “What’s worse is that this virus becomes one that can be easily transmitted between humans and cause serious illness. »

Experts say the disease has already exceeded all expectations, from its ability to infect diverse species to its international reach and duration. That should make its appearance on an industrial mammal farm a cause for increased scrutiny and concern, said Crystal Heath, a Bay Area veterinarian and co-founder of Our Honor, an animal welfare organization.

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

And it’s still unclear how widespread the virus is or how long it has been infecting livestock, Weese said.

The fact that observers have noticed a drop in milk production in states now known to have infected herds suggests it could last for weeks or months. And if symptoms were mild enough in cattle and humans that they didn’t warrant a trip to the vet or doctor, they could be circulating and even more likely to progress, Weese said – including the discovery of a mammalian host affected by human and avian influenza, which would allow mixing and recombination.

That’s why many are now turning to farmed pigs, said Matthew Hayek, an assistant professor of environmental studies at New York University in the Department of Environmental Studies. Pigs are considered efficient and worrisome flu recombination factories – mammalian vessels that mix human and avian flu viruses with potentially lethal ease.

“This is a problem not only for the sake of our food production,” he said, “but for the sake of our security as a species.”