New Bird Flu Strain Found in Nevada Dairy Worker

The worker, exposed to infected cattle at a Churchill County dairy, had mild symptoms and did not need hospitalization.

Dairy cattle feed at a farm near Vado, N.M., on March 31, 2017. Rodrigo Abd/AP Photo

A dairy worker in Nevada has been infected with a novel strain of bird flu, marking the first time this particular version of the virus has been traced to a cow, according to the Central Nevada Health District on Feb. 10.

The Centers for Disease Control and Prevention (CDC) has also confirmed the case.

The worker, who was exposed to infected dairy cattle while working at a farm in Churchill County, experienced mild symptoms that did not require hospitalization.

“The person had conjunctivitis with no other reported symptoms and is recovering. … There is currently no evidence of person to person spread of this virus,” the Central Nevada Health District said in a statement.

The bird flu, currently spreading through animals and some people, is known to scientists as Type A H5N1 influenza. There are different strains of it, with a version known as B3.13 confirmed in March after spreading to cattle in late 2023, scientists said. It has infected 962 herds of cattle in 16 states, with most cases occurring in California.

This new strain, known as D1.1, is distinct from the B3.13 version. The D1.1 strain was initially confirmed in Nevada cattle on Jan. 31 from milk samples collected as part of a monitoring program that began in December. Before then, the D1.1 version had been detected in a number of people exposed to poultry.

The CDC said on Feb. 10 that available data shows that D1.1 likely infected a total of 15 people in five states—Iowa, Louisiana, Oregon, Washington, and Wisconsin—all related to poultry last year.

Potential for Wider Spread

The discovery of the D1.1 strain in cattle suggests that the virus has spread from wild birds to cattle on at least two separate occasions. Experts suggest that this raises concerns about the potential for wider spread.

Andrea Garcia, vice president of science, medicine, and public health at the American Medical Association, stated in a YouTube video posted by the group on Feb. 10 that “Some experts do fear that it could mark a new chapter in the outbreak or that bird flu may become endemic in the U.S. This is something we are continuing to very closely follow.”

However, the risk to the public for H5N1 bird flu remains low, according to the CDC.

Meanwhile, health officials are taking measures to prevent the spread of the virus further.

“Close contacts of the infected person and other workers exposed at the farm are being contacted and monitored for symptoms and are being offered personal protective equipment (PPE), testing and antiviral medication,” according to the Central Nevada Health District.

The Central Nevada Health District also recommends several steps to protect against infection, including avoiding touching sick or dead animals or their droppings, cooking animal products to the appropriate temperature, avoiding uncooked food products such as unpasteurized raw milk or cheeses, and reporting dead or sick birds or animals to the USDA Wildlife Services. They also recommend poultry and livestock owners report sick or dead animals to their veterinarians and the Nevada Department of Agriculture.

Dairy Farms in California

As of Feb. 10, the U.S. Department of Agriculture’s (USDA) laboratories have confirmed H5N1 bird flu in 29 dairy farms in the last 30 days in California, according to the California Department of Food and Agriculture (CDFA).

Since California’s first detection of H5N1 bird flu in dairy cattle in August 2024, there have been a total of 739 infected dairies, with 280 of those fully recovering and being released from quarantine.

The CDFA is managing multiple USDA-funded research projects to better understand the virus so the state can adjust strategies to combat the evolving virus, according to a Feb. 6 press release from the agency.

The nationwide outbreak of H5N1 bird flu began in poultry in 2022.

The Associated Press contributed to this report.

From NTD News