Avian flu first made the jump from birds into dairy cows on farms in a number of US states in spring 2024. Until now, all such cases of the H5N1 virus have been ascribed to a genotype called B3.13, but the US Department of Agriculture (USDA) has just announced the detection of a second genotype,

A pandemic is not inevitable, scientists say. But the outbreak has passed worrisome milestones in recent weeks, including cattle that may have been reinfected.

Dairy cattle in Nevada have been infected with a new type of bird flu that’s different from the version that has spread in U.S. herds since last year, Agriculture Department officials said Wednesday.