Six dairy herds in Nevada have tested positive for a newer variant of the H5N1 bird flu virus that’s been associated with severe infections in humans, according to the Nevada Department of Agriculture.

In the US state of Nevada, a newly identified H5N1 bird flu strain, D1.1, has been found in six dairy herds. Scientists warn the virus could become endemic, posing risks to livestock and human health.

At least four cattle herds in Nevada have tested positive for a strain of H5N1 bird flu never before seen in cows, state agriculture officials confirmed Wednesday, and respiratory symptoms like coughing and sneezing have been reported.