Highly pathogenic avian influenza (HPAI) has, as of April 4, been detected in dairy herds in six states. The National Veterinary Services Laboratory in Ames, Iowa, which is operated by the USDA Animal and Plant Health Inspection Service (APHIS), has confirmed positive test results from seven dairy herds in Texas, two in Kansas, and one each in Michigan, New Mexico, Idaho and Ohio.
The first cases in U.S. cattle were confirmed in Texas and Kansas on March 25 after several weeks of speculation about a “mystery illness” affecting dairy herds in the Southwest and southern Plains. Multiple affected farms reported finding dead wild birds on their property, which are believed to be the source of the HPAI infections. It was initially thought that cattle and other ruminants are “dead-end” hosts – meaning that, while they can contract the disease, they cannot transmit it to other animals. However, after weeks of seeing how the sickness spreads throughout these dairy herds, veterinarians and pathologists have begun to question the veracity of the dead-end host belief.
Illness from HPAI in cattle is relatively mild, with symptoms including decreased lactation, loss of appetite, fever and a drop in rumen motility lasting only a few days. To date, symptoms have occurred mostly in older dairy cows.
So far, HPAI has not been detected in beef cattle. Milk from sick cattle is not marketed, and officials continue to be confident in pasteurization’s effectiveness against viruses such as HPAI. The USDA reports no concern about the safety of the commercial milk or meat supply.
APHIS has created a webpage with recent announcements pertaining to HPAI detections in livestock, as well as biosecurity information and other resources.
