Nevada dairy cows infected with deadly new strain of bird flu

In the United States, dairy cattle in Nevada have been infected with a new genotype of the H5N1 bird flu virus, marking a concerning development in the ongoing outbreak of avian influenza. The U.S. Department of Agriculture (USDA) confirmed that the D1.1 strain of the virus was detected during routine milk testing results announced on January 31, 2025. This incident signifies that H5N1 has spilled over into cows not once but twice, with previous infections associated with a different strain known as B3.13. The D1.1 strain has already been linked to human infections, including a fatal case in Louisiana earlier in January. Health experts are alarmed by the implications of these findings, highlighting a rising concern that this virus may more easily jump between species than previously understood. The USDA reported that until this detection, all dairy herd infections had been linked to the B3.13 genotype, with only mild symptoms observed in affected workers. The introduction of the D1.1 strain raises questions about the potential for more severe illness in humans, particularly dairy workers who frequently interact with cows. Experts are also emphasizing the importance of ongoing testing and surveillance to prevent the virus from establishing a foothold in domestic mammals like cows. The USDA's National Milk Testing Strategy, which began implementation in late December 2024, played a crucial role in identifying this new strain, underpinning the necessity of proactive measures in monitoring the pathogen's spread. The findings underscore a broader epidemiological challenge in managing and containing avian influenza, particularly as it continues to affect wildlife and domesticated animals across the country. With nearly 950 confirmed cases among cattle in different states, the pandemic potential of different H5N1 strains necessitates thorough investigations and decisive governmental responses to mitigate risks associated with animal-to-human transmission. This unprecedented outbreak in cows represents one of the first instances of H5N1 bird flu impacting dairy cattle, heightening awareness of the virus's ability to mutate and adapt to new hosts. While the public health risk remains classified as low, scientists and authorities are urging constant vigilance and expedited sharing of data relating to the genetic sequences of viral strains. The USDA intends to post further genetic details to a public repository soon, seeking to facilitate research that can shed light on the transmission dynamics of H5N1 and its potential consequences for both humans and animals.