Last updated on February 17th, 2025 at 12:08 pm

I do not get the raw milk craze in the USA because it is dangerous, and now it could contain bird flu. The best milk is pasteurized because it eliminates dangerous pathogens without changing the essential nature of the milk. But like the fads for organic and gluten-free foods, raw milk has fans in groups that overlap greatly with the anti-vaccine crowd. Of course.

Of course, Donald Trump’s nominee for Secretary of Health and Human Services, anti-vaxxer Robert F Kennedy Jr, has vowed to allow wider distribution of raw milk across America.

This post will examine raw milk and the huge risk of bird flu.

What is bird flu?

Avian influenza, what everyone is now calling “bird flu,” is a subtype of type A influenza, designated as A(H5N1). Without getting into all the details of the naming system, the designation is based on antigens common to this subtype of influenza. There is another avian influenza designated as A(H7N9), but the current outbreak appears to be the H5N1 subtype.

As the name implies, these viruses usually affect birds but they can occasionally pass from birds to humans, cows (where it can contaminate raw milk), pigs, and other animals. The H5N1 subtype arose in Asia a few years ago and has spread across the world. It is highly pathogenic (meaning it can cause disease in humans) and has passed to humans several times.

Infected birds shed the bird flu virus through their saliva, mucous, and feces. Human infections with bird flu viruses can happen when the virus gets into a person’s eyes, nose, or mouth, or is inhaled. This can happen when the virus is in the air (in droplets or possibly dust) and a person breathes it in, or possibly when a person touches something that has the virus on it and then touches their mouth, eyes, or nose. Human infections with bird flu viruses have occurred most often after unprotected contact with infected birds or surfaces contaminated with bird flu viruses. However, some infections have been identified where direct contact with infected birds or their environment was not known to have occurred.

There are numerous cases where bird flu has been transmitted between humans, but most infections of humans are from constant contact with infected birds. Human infection with avian influenza A virus poses pandemic potential, so CDC and other public health agencies investigate every case to assess whether human-to-human transmission might have occurred. Detailed public health investigations can help determine whether person-to-person spread of an avian influenza A virus occurred.

The signs and symptoms of bird flu infections in humans can range from nothing to severe. The infections are similar to other flu infections including fever, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, fatigue, and shortness of breath.

H5N1 has been around for a few years, and the CDC has stockpiles of vaccines for the H5N1 and H7N9 subtypes. And if either avian influenza mutates, the CDC has a method to quickly develop new vaccines.

Bird flu and raw milk

Bird flu was first confirmed in US dairy cattle in March 2024, and since then, it has spread widely. In California, more than 435 separate dairy herds have seen bird flu infections, more than all other US states combined. High levels of the virus have been found in the milk of infected cows.

About 20% of samples of pasteurized milk sold in stores were found to contain H5N1 viral remnants (which cannot cause disease). Pasteurization, or heat treatment, not only kills the bird flu virus but also bacteria such as E. coli, listeria, and salmonella, which are known human pathogens.

Officials with California’s Department of Food and Agriculture have been conducting weekly tests of raw milk in bulk tanks from the state’s dairies. Additional tests conducted at Raw Farm sites in California were negative for the virus, but officials said they would begin testing for bird flu twice a week.

Because of the bird flu contamination, California has had to recall some brands of raw milk.

Summary

As of today, we have no evidence that raw milk has actually infected people with bird flu. At least 55 people in the USA are known to have been infected by the virus this year, but nearly all were dairy or poultry workers who developed a mild illness after close contact with infected animals.

Research has shown that mice fed raw milk contaminated with bird flu became very ill. Another 2024 study showed that of 24 domestic cats that were fed milk from sick cows on a north Texas dairy farm, more than half became sick and died in mid-March, presumably of bird flu infection.

The cats had signs of systemic influenza infection, including depressed mental state, stiff body movements, ataxia, blindness, circling, and copious oculonasal discharge, the researchers reported. Neurological examination found no menace reflexes and pupillary light responses with weak blink response.

These studies do not provide evidence that raw milk could pass H5N1 disease to humans, but they are concerning.

Even though the current risk is low, the problem is that H5N1 could evolve into a strain that could acquire the ability to infect and be transmitted easily in humans in a sustained manner. That would lead to a pandemic. And raw milk could become the source of that new strain of H5N1.

The claims about raw milk are based on pseudoscientific nonsense recently pushed by right-wing commentators. However, the FDA says it’s unsafe, the CDC says it’s unsafe, and numerous other sources say it’s unsafe.

So raw milk has no science-based benefits and has a huge amount of science-based risks, including spreading bird flu. But the crackpots that are going to head America’s healthcare system don’t care about scientific evidence.

Citations

• Burrough ER, Magstadt DR, Petersen B, Timmermans SJ, Gauger PC, Zhang J, Siepker C, Mainenti M, Li G, Thompson AC, Gorden PJ, Plummer PJ, Main R. Highly Pathogenic Avian Influenza A(H5N1) Clade 2.3.4.4b Virus Infection in Domestic Dairy Cattle and Cats, United States, 2024. Emerg Infect Dis. 2024 Jul;30(7):1335-1343. doi: 10.3201/eid3007.240508. Epub 2024 Apr 29. PMID: 38683888; PMCID: PMC11210653.
• Guan L, Eisfeld AJ, Pattinson D, Gu C, Biswas A, Maemura T, Trifkovic S, Babujee L, Presler R Jr, Dahn R, Halfmann PJ, Barnhardt T, Neumann G, Thompson A, Swinford AK, Dimitrov KM, Poulsen K, Kawaoka Y. Cow’s Milk Containing Avian Influenza A(H5N1) Virus – Heat Inactivation and Infectivity in Mice. N Engl J Med. 2024 Jul 4;391(1):87-90. doi: 10.1056/NEJMc2405495. Epub 2024 May 24. PMID: 38785313.