Mice became sick within 24 hours after consuming unpasteurized cow milk contaminated with the highly pathogenic avian influenza virus, according to a study conducted by the Texas A&M Veterinary Medical Diagnostic Laboratory.
The mice exhibited signs of illness, such as ruffled fur and lethargy. High levels of the virus were detected in their organs, including the mammary glands of two non-lactating mice.
The data from the study, published in the
New England Journal of Medicine, suggest that susceptible animals consuming untreated milk containing the pathogenic avian influenza virus can become infected. “In summary, HPAI H5-positive milk poses a risk when consumed untreated,” the research team wrote.
When the researchers pasteurized the milk, they found that the virus levels were reduced. Consequently, the amount of the virus detected in the mice was also lower. However, pasteurization did not entirely eradicate the virus.
CDC Monitors for Human Transmission
On March 25, 2024, bird flu was first reported in dairy cows, according to the
U.S. Centers for Disease Control and Prevention. This marked the first time ever bird flu viruses had been found in cows.
The CDC confirmed one human infection on April 1 due to exposure to infected dairy cows in Texas. The person developed conjunctivitis, or pink eye, with red eyes but quickly recovered. On May 22, the CDC reported a second human case involving exposure to infected dairy cows in Michigan. Overall,
more than 300 people have been monitored for exposure to infected or potentially infected animals, with at least 37 developing flu-like symptoms.
“Dairy cows are a new and unexpected host of this virus, which has been spreading mostly among wild birds and poultry in the United States since January 2022, with sporadic infections in other species,”
the CDC stated.
Since 2022, the USDA has reported the highly pathogenic avian influenza virus in
over 200 mammals. While rare, mammals can become infected with the bird flu. Despite the virus spreading to dairy cows and being found in raw milk, the risk of transmission to humans has not increased. However, people with job-related or recreational exposure to infected birds, animals, or cows are at the highest risk of infection.
Raw Milk Not Recommended For Consumption
The CDC recommends against consuming raw milk. The agency notes that drinking tainted milk does not protect against future diseases; instead, it could cause illness.
Raw milk is milk that has not undergone pasteurization, a process that removes disease-causing germs by heating the milk to a specific temperature for a certain duration.
Pasteurized milk offers the same nutritional benefits as raw milk without the risks associated with its consumption, according to the CDC. These risks include exposure to harmful pathogens such as E. coli, listeria, brucella, salmonella, campylobacter, and cryptosporidium.
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