Despite H5N1 bird flu outbreaks in dairy cattle, raw milk enthusiasts are uncowed

Holstein cows at Riverview Dairy in Pixley, California, on March 12, 2020. The liquid part of their manure is directed into a nearby anaerobic digester, which captures methane that would otherwise be emitted into the atmosphere.
Holstein cows feed on hay at a California dairy farm. Bird flu has not been detected in California's dairy herds. (Mel Melcon / Los Angeles Times)

Government scientists are warning consumers to stay away from raw milk, citing research showing "high viral load" of avian influenza in samples collected from infected cows — as well as a disturbing cluster of dead barn cats who'd consumed contaminated raw milk.

“We continue to strongly advise against the consumption of raw milk,” said Donald Prater, acting director of the Center for Food Safety and Applied Nutrition at the Food and Drug Administration.

But raw milk enthusiasts are doubling down on the claimed benefits and safety of their favorite elixir, and say the government warnings are nothing more than "fearmongering."

Read more: Federal government 'believes' virus found in grocery store milk is safe for consumption

Mark McAfee, founder of Fresno's Raw Farm and the Raw Milk Institute, said his phone has been ringing off the hook with "customers asking for H5N1 milk because they want immunity from it." (Bird flu has not been detected in California's dairy herds.)

Other raw milk drinkers, such as Peg Coleman, a medical microbiologist who runs Coleman Scientific Consulting, a Groton, N.Y.-based food safety consulting company, claimed the government's warnings have no basis in reality.

Coleman, who is an advisor to the Raw Milk Institute, has provided expert testimony on the benefits of the unpasteurized dairy product in courtrooms across the nation.

"It's a fear factor. It's an opinion factor. It's based on 19th century evidence. It's absolutely ridiculous," she said, citing research that shows healthy gut biomes and breast milk provide immune system benefits.

The process of heating milk to a specific temperature for a specific period of time and then allowing it to rapidly chill is named for the French chemist and germ theory pioneer Louis Pasteur. Recently, the FDA reaffirmed the effectiveness of pasteurization in destroying Highly Pathogenic Avian Influenza (HPAI) and other viruses, as well as harmful pathogenic bacteria and other microorganisms.

Coleman, however, says the risk of illness are overblown.

"This is all people's opinions, their gut feelings, their ignorance," she said. "I think that if there were a study done, and the microbiota of raw milk drinkers was tested, you might very well find a healthier gut microbiota that's better able to withstand occasional challenges."

It's a message that health officers and food safety experts say is dangerous and foolhardy, especially at a time when government investigators are scrambling to understand the extent of dairy herd outbreaks, and the potential for harm.

"Deliberating consuming raw milk in the hope of becoming immune to avian influenza is playing Russian roulette with your health," said Michael Payne, a researcher and outreach coordinator at the Western Institute for Food Safety and Security at UC Davis. "Deliberately trying to infect yourself with a known pathogen flies in the face of all medical knowledge and common sense."

He and other food safety experts say the safest way to consume dairy is to ingest only pasteurized milk products.

"It's been the gold standard for more than a century," he said.

Read more: 'Nobody saw this coming'; California dairies scramble to guard herds against bird flu

The highly pathogenic avian influenza virus has been found in 36 herds in nine states, and detected in samples of commercially sold, pasteurized milk. Testing has shown those viral fragments to be inactive — neutralized by the pasteurization process.

The live virus, on the other hand, has been detected in raw cow's milk and colostrum — the nutrient rich milk expressed by mammals in the first days after giving birth — and a study that examined dead barn cats at bird-flu-infected dairies in Texas and Kansas suggests contaminated raw milk could be dangerous for other mammals, including humans.

However, the researchers were unable to definitively show the cats acquired the virus via raw milk; it is possible they consumed diseased birds.

It's a point that Coleman has seized on — highlighting it as proof that the government's caution regarding drinking raw milk is specious.

"Show me that it infected the cats through the GI tract," she said. "Otherwise, you are just ... crying wolf trying to blame raw milk or saying ... that raw milk is inherently dangerous, even when the scientific evidence does not support that opinion."

She noted that the cats' symptoms were not gastrointestinal in nature. Instead, they developed depressed mental states, their bodies showed stiff movements, they lost coordination, produced discharge from their eyes and noses, and suffered blindness. More than half of the farms' cats died. She said even if the cats had contracted the virus via the milk, it was likely a result of breathing in milk droplets rather than from consuming it.

"Have you ever seen a cat eat?" asked Coleman. "It's messy. If they got the disease from the milk, it's probably because they breathed it in."

Eric Burrough, a professor and veterinary diagnostic pathologist at Iowa State University who led the cat study, acknowledged that there were things they were unable to control for and other things "we do not know"; the analysis was "diagnostic."

But he and his team were able to show that the cats fed on contaminated raw milk with high concentrations of the virus and that the pattern of infection and death "does not align with random exposure to wild birds," he said.

As for Coleman and McAfee's belief that stomach acid and a healthy gut biome would offer protection, he noted previous studies that showed cats eating wild birds did get the virus, suggesting those safeguards are not sufficient to protect mammals against bird flu.

Read more: California wildlife is vulnerable to an avian flu ‘apocalypse.’ What is driving the spread?

He said "there is also the possibility that virus could enter via the tonsils in the pharynx of the cats prior to ingestion in both the bird consumption and milk consumption scenarios."

In any case, said Payne, there's enough concern out there right now that should give people pause about consuming dairy products that have not been pasteurized.

Even Coleman acknowledged that toddlers and young children — who have been known to be messy eaters — might consume milk differently than adults. And if her messy eating theory has weight with the cats, "it's something to think about" with children.

So far, the virus does not seem to have evolved any genetic adaptations that would make it more amenable to pass between people.

Only one person — a Texas dairy worker infected in March — has so far been reported to have acquired the disease from cattle. His symptoms were mild — just a moderate case of conjunctivitis, or pink eye, according to a case report in the New England Journal of Medicine.

Local and state health departments have tested about 25 other people for the virus and monitored more than 100 for symptoms.

This particular bird flu virus originated in China in 1996, but the clade — or subvariant, known as — found in U.S. dairy cattle became dominant in 2020. It has since killed hundreds of millions of domestic and wild birds — and has been detected on every continent except Australia. It has also jumped to mammals, and is responsible for killing at least 48 different species, including elephant seals, dolphins and sea lions.

Researchers now believe this clade of H5N1 virus was introduced by birds to cattle at one site in the Texas Panhandle, and then spread by cattle-to-cattle transmission as cows were moved between different farms. Evidence also shows that infections have spread from cattle to domestic poultry. And samples have been discovered in wastewater.

There have been 887 confirmed cases of H5N1 human infection across 23 countries since 2003. Of those, 462 were fatal. It is unclear if there were more mild cases that went undetected, something that could potentially reduce the 52% fatality rate.

However, epidemiologists say HPAI is dangerous — and potentially fatal. Considering the global, cross-species spread of illness, they are urging people to be cautious and avoid raw milk.

This story originally appeared in Los Angeles Times.