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Raw Milk and Raw Milk Products May Contain the Bird Flu Virus

Time to avoid raw milk and raw milk cheeses. The bird flu virus (H5N1) has been spreading among dairy cows for months, and now scientists are finding extremely high amounts of the bird flu virus in cows' milk. The good news is that pasteurization will kill the virus.

The big concern is that somehow the virus will mutate and start infecting humans on a large scale. Besides cattle, there have been outbreaks of the virus in over 200 species of mammals since 2022. Millions of wild birds have died from the virus.

The National Institute of Health (NIH) reports that: 1) The H5N1 bird flu virus survived in raw dairy milk kept under refrigerated conditions for at least 5 weeks (they didn't test beyond that point). 2) When mice consumed infected raw milk, they showed signs of illness. This suggests that drinking raw milk may pose a risk of transmission to people. 3) Pasteurization "neutralized" the virus

The CDC says it's not just raw milk, but also any raw milk dairy products - cheeses, yogurt, ice cream can be contaminated by the virus and to avoid eating them.

The following article reports that as of June 5, H5N1 infections have been confirmed in more than 80 dairy herds in 9 states and in 3 dairy farm workers, who had mild symptoms (first 2 had conjunctivitis type eye symptoms, the 3rd had respiratory symptoms). A number of cats have died from the virus after ingesting raw milk.

Excerpts from Nature: Huge amounts of bird-flu virus found in raw milk of infected cows

Milk from cows infected with bird flu contains astronomical numbers of viral particles, which can survive for hours in splattered milk, new data shows1,2. The research adds to growing evidence that the act of milking has probably been driving viral transmission among cows, other animals and potentially humans.

That’s a better scenario for public health than transmission through airborne particles, which would be more difficult to contain. “It’s good news it’s probably spreading by the milking process,” says Martin Beer, a virologist at the Federal Research Institute for Animal Health in Greifswald, Germany. This means that changes to milking procedures could help to bring the outbreak under control and prevent human infections.

A virus that’s going places

Since it was first isolated in 1996, the highly pathogenic bird-flu virus H5N1 has caused outbreaks in domestic and wild birds around the world, and it has occasionally infected mammals such as seals and foxes. On 25 March, US health officials announced that H5N1 had been detected in dairy cows for the first time. As of 5 June, infections have been confirmed in more than 80 dairy herds in nine states and in three dairy farm workers, all of whom had mild symptoms.

Scientists had not previously suspected that cattle could easily become infected with bird flu, because the animals were thought to lack the receptor allowing the virus to enter their cells. But reports of sick cattle with inflamed udders raised suspicions that the virus can infect the animals’ mammary glands.

Viral milkshake

Diel and his colleagues examined the milk of cows with H5N1 and found astonishing amounts of virus: some samples contained hundreds of millions of infectious particles, a level “that is higher than we can grow in the lab” for experiments, says Seema Lakdawala, an influenza virologist at Emory University School of Medicine in Atlanta, Georgia. “In ideal conditions, we don’t get that — this is crazy high.”

This abundance could help to explain why H5N1 viral fragments have been found in one in five retail milk samples: a small number of infected cows could taint the milk supply with many particles. (Pasteurization inactivates H5N1 in milk, according to a preprint7 posted last week.)

The findings suggest that minimizing exposure to raw milk could be an important way to prevent transmission. 

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