US finds traces of bird flu virus in pasteurized milk

US health officials announced on April 23 that they had detected fragments of the bird flu virus in the nation's pasteurized cow's milk supply during a large-scale study of the impact of bird flu on dairy farms.

However, US authorities say these virus fragments may not be harmful to human health.

The study comes as an outbreak of highly pathogenic H5N1 avian influenza has spread among dairy herds in the United States, with one person in Texas contracting a mild form of the disease.

The current H5N1 outbreak has killed millions of birds, but cows infected with the virus do not develop severe illness.

The US Food and Drug Administration (FDA) announced that during nationwide testing, they discovered influenza virus fragments in “milk from infected animals, in processing systems, and on store shelves.”

Experts used a highly sensitive quantitative polymerase chain reaction (qPCR) test, which can detect remnants of genetic material from the pathogen, to determine whether the heat used during milk pasteurization inactivated the virus.

The US FDA emphasized: “The milk pasteurization process has served the public health well for over 100 years. Even when viruses are detected in raw milk, the pasteurization process can help remove pathogens to a minimum level and does not pose a health risk to consumers.”

FDA scientists are also working to further investigate the virus-positive samples by using "egg viability studies."

In this method, the virus is injected into a sample of embryonated chicken eggs and then monitored to see whether the virus replicates.

The FDA is currently conducting additional analysis of dairy products on the market to assess any potential differences between various dairy products, such as whole milk, cream, etc.

Previously, the bird flu virus was also detected in raw milk (fresh, unpasteurized cow's milk) - a type of milk that health authorities have long advised against consumption.