Bird Flu Spread for Four Months in US Dairy Cows Without Being Detected

 

Bird flu in US dairy cows

Bird flu, a highly pathogenic virus known as H5N1, had been silently circulating among dairy cows in the United States for at least four months before scientists and government regulators confirmed its presence. A new analysis of genomic data by scientists at the US Department of Agriculture's Animal Disease Center reveals this disturbing reality.

This study, posted on the BioRXIV server as a preprint, reveals that the H5N1 virus likely moved from wild birds to cows between mid-November and mid-January, meaning it was active in the dairy industry long before it was identified. Additionally, infected cows were found with no apparent connections, suggesting that the extent of the outbreak could be much larger than has been documented so far.

Official confirmation of the presence of the virus in dairy cows occurred on March 25 in Texas. Since then, at least three dozen infected herds have been recorded in nine states.

Alarmingly, at least one farm worker who came into contact with infected cows also tested positive for H5N1, becoming the second human case of this type of flu ever reported in the United States. Fortunately, the worker recovered after receiving antiviral medication.

Tests in milk

Tests on milk samples from retail stores have revealed traces of the virus in about one in five samples, indicating the widespread spread of the infection. Although it has been confirmed that the virus in pasteurized dairy products is not active and does not pose a health risk, consumption of raw milk is discouraged.

Dr. Michael Worobey, of the Department of Ecology and Evolutionary Biology at the University of Arizona, points out that steps could have been taken to detect H5N1 much earlier if metagenomic sequencing, a technique that allows multiple pathogens to be identified in a single time, had been used. sample.

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The study also reveals how the virus spread rapidly among herds across the United States. Samples collected between March and April found very similar H5N1 viruses in flocks and flocks of poultry in several states, suggesting a mass contagion event between wild birds and cows.

Additionally, evidence of virus transmission between livestock and domestic birds was found, as well as evidence of infection in wild animals and pets near dairy farms.

This discovery raises concerns about the possible evolution of the virus in the dairy cattle population, which could pose an ongoing threat to public health for years to come. However, it is unclear whether this virus has the potential to start a human pandemic, its roots in a species as important as dairy cows increase the risk for everyone.

According to Worobey, this event highlights the need for a change in the way animal disease outbreaks are addressed. It urges regulators to adopt more advanced testing techniques and abandon the “wait and see” mentality when it comes to identifying emerging pathogens.