Dairy cows had been carrying H5N1 bird flu for four months before it was discovered, according to USDA researchers.
The recent study has uncovered more infected cattle, indicating that there could be other unidentified herds carrying the H5N1 virus. This discovery raises concerns that the virus may have been in the US dairy industry for months before experts were made aware of it.
The USDA's research, published on the BioRXIV server, supports the findings of an independent group of over twenty evolutionary and molecular biologists who analyzed the raw genome sequences uploaded by the government. Both groups suggest that the virus had crossed over from wild birds to cows between mid-November and mid-January, indicating that it was present for an extended period before detection.
The H5N1 virus was confirmed in dairy cows in Texas by the USDA on March 25, prompting at least thirty-six infected herds across nine states. One farmworker also tested positive for the virus, the second reported case in the United States. However, the worker received antiviral medication and made a full recovery.
The US Food and Drug Administration revealed traces of the virus in about one-fifth of milk samples from retailers. Though these viruses were inactive, they could not harm humans. Regardless, experts recommend avoiding raw milk consumption as a precaution.
In response to these incidents, Dr. Michael Worobey, head of the Department of Ecology and Evolutionary Biology at the University of Arizona, remarks that action could have been taken earlier to detect the virus. Worobey, who led the group of biologists analyzing the samples, suggests using a technique called metagenomic sequencing, which examines all genetic material in a sample and employs computers to isolate relevant information. If this method had been used, H5N1 might have been detected in January.
Worobey emphasizes the need for regulations to change in detecting pathogens potentially leading to human pandemics. Instead of waiting for sick cows or people, he recommends regular testing of animals using modern techniques for identifying emerging pathogens.
Examining the USDA's account, the study reveals how the H5N1 virus likely spread quickly across the US. Samples taken between March 7 and April 8 revealed almost identical H5N1 viruses in 26 herds in eight states and six poultry flocks in three states, implying a single spillover from wild birds to cows. The research also noted that domestic poultry flocks were infected through different transmission routes. Additionally, the virus infected a raccoon and cats living near the cows on dairy farms.
Interestingly, the virus from the infected farmworker was sequenced and revealed differences from the cow genomes. The scientists believe that these variations could be due to missing samples from the animals the worker interacted with or possible virus evolution between hosts.
Worobey notes that the virus is likely to stay in the dairy cattle population for an extended period, potentially for years to come. While it's uncertain whether this strain will mutate to cause a human pandemic, Worobey emphasizes that allowing a virus to establish itself in a domesticated species can pose risks to humans.
"It adds one more species – a very important species – that didn't have influenza A virus circulating in it before to the list of species where these viruses can have the opportunity to find that right combination that allows them to wreak havoc in the human population, not just animals," Worobey warned.
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Source: edition.cnn.com
