A recent discovery in Nevada has revealed that dairy cattle have been infected with a novel strain of bird flu, distinct from the variant that has been circulating among U.S. herds since the previous year. The Department of Agriculture officials disclosed this information on Wednesday, indicating that multiple forms of the virus, classified as Type A H5N1, have crossed over from wild birds into cattle on at least two separate occasions. This development has raised concerns among experts about the broader transmission and the challenges associated with controlling infections in both animals and individuals who have close contact with them.
Renowned influenza expert, Richard Webby, from St. Jude Children’s Research Hospital, expressed surprise at the revelation, stating, “I always thought one bird-to-cow transmission was a very rare event. Seems that may not be the case.” The new strain, identified as D1.1, was detected in Nevada cattle, distinct from the previously identified B3.13 version that was confirmed earlier in March after infecting numerous herds across 16 states. The D1.1 strain was discovered in milk samples collected as part of a surveillance program initiated in December, underscoring the importance of continued testing efforts, as emphasized by virus expert Angela Rasmussen from the University of Saskatchewan in Canada.
The emergence of the D1.1 strain is significant as it has been linked to the first reported death in the U.S. associated with bird flu, as well as a severe illness case in Canada. Tragically, a resident of Louisiana succumbed to the virus in January after experiencing severe respiratory symptoms following contact with wild and backyard birds. Similarly, in British Columbia, a teenage girl was hospitalized for an extended period due to a virus traced back to poultry sources. The U.S. Centers for Disease Control and Prevention reported that around 67 individuals in the U.S. have been infected with bird flu, predominantly individuals working closely with dairy or cattle.
In response to these concerning developments, USDA officials have announced plans to share genetic sequences and other pertinent information regarding the new virus strain on a public repository in the coming week. Scientists stress the importance of this data-sharing initiative to gain insights into the timeline of the spillover event and the potential extent of the virus circulation. Evolutionary biologist Michael Worobey from the University of Arizona, who has extensively studied the H5N1 virus in cattle, emphasized the critical need for swift dissemination of information about the virus, given its pandemic potential, which he believes could surpass the impact of COVID-19.
Worobey underscored the significance of timely information-sharing for national security, global health security, and the overall well-being of individuals, animals, and businesses in the U.S. The gravity of the situation cannot be understated, and proactive measures are imperative to mitigate the risks posed by this emerging health threat.
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The Associated Press Health and Science Department is supported by the Howard Hughes Medical
