USDA data indicates highly pathogenic avian influenza (HPAI or bird flu) outbreaks in poultry and dairy cattle have sharply decreased in the past few weeks. This tracks with a similar decrease last year. No cases of bird flu have been found in commercial poultry flocks since July 19 and only three dairy herds since August 5.

The most recent bird flu cases in dairy were two herds in Colorado and one in Idaho. Colorado is the only state that requires weekly tests for bird flu. Milk samples from every farm are tested. The state accounts for 64 of the 192 dairy herds in 13 states.

Bird flu is spread by migratory waterfowl and their droppings. This makes outbreaks more common during the colder months of the year. Last year, the virus disappeared from commercial bird flocks from April 15 until October 4. The USDA stresses the importance of biosecurity on the farm to prevent the spread of the virus.

Bird flu has been reported among animals worldwide. Maurice Pitesky, an expert in poultry disease modeling at the University of California-Davis, explained the recent outbreak is magnitudes larger and more complex than previous outbreaks.

Read more about the decrease in bird flu infections here.