The strain was identified on Jan. 31 through genome sequencing of milk from the state as part of the USDA’s nationwide mass milk-testing program.
A new type of highly pathogenic avian influenza (HPAI) has been detected in dairy cattle in Nevada, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) said in a Feb. 5
statement.
The strain was discovered in six herds and is different from the version of HPAI, or bird flu, that has spread in cows throughout the United States since last year, officials said.
The new strain discovered in Nevada dairy cattle is of genotype D1.1. Previous detections in dairy cattle have been of genotype B3.13, according to the agency.
Genotype D1.1. was the predominant genotype among wild birds this past fall and winter and has been identified in wild birds, mammals, and spillovers into domestic poultry, the agency said.
According to the agency, the strain was identified on Jan. 31 through genome sequencing of milk from Nevada as part of the U.S. Department of Agriculture’s (USDA) nationwide mass milk-testing
program.
“APHIS continues to work with the Nevada Department of Agriculture by conducting additional on-farm investigation, testing, and gathering additional epidemiological information to better understand this detection and limit further disease spread,” the USDA said in the statement.
The D1.1 version of the virus was linked to the first U.S. human fatality tied to bird flu. The individual was over the age of 65 and was reported to have underlying medical conditions. The person contracted H5N1 after being exposed to wild birds and a “non-commercial backyard flock,”
according to the Louisiana Department of Health.
That same version has also been linked to
severe illness in a teenager from British Columbia, who was hospitalized in critical condition last fall, as well as to outbreaks in Washington state.
Nevada Dairy Cattle Quarantined
The agency said the discovery of the latest strain of bird flu does not impact its eradication strategy for the virus and is a “testament to the strength of our National Milk Testing Strategy (NTMS).”
It added that it plans to publish a technical brief on the findings on its official website and will post the sequence data on
GenBank in the coming weeks, as part of efforts to share information of import to the scientific community.
In a separate
statement published on Jan. 31, the Nevada Department of Agriculture (NDA) said two herds of dairy cattle had been placed under quarantine in the counties of Nye and Churchill due to bird flu detections.
The department said testing was underway to confirm what strain of the virus has been detected in Churchill County but that preliminary results showed the detection to be consistent with a strain that has also been detected in wild birds in all North American flyways.
NDA Director J.J. Goicoechea stressed the importance of keeping equipment clean, practicing good animal health safety practices, and bolstering biosecurity measures to prevent the spread of disease.
Since March 2024, H5N1 avian influenza has been detected in nearly 958 cow herds in 16 states,
according to the USDA.
A total of 67 human cases of bird flu infection have been reported in the United States across eight states since April 2024,
according to the Centers for Disease Control and Prevention.
Reuters and The Associated Press contributed to this report.
