The first reported case of highly pathogenic avian influenza (HPAI) in Oregon has been confirmed, according to the U.S. Department of Agriculture (USDA).
USDA’s Animal and Plant Health Inspection Service (APHIS) National Veterinary Services Laboratories (NVSL) confirmed via PCR (polymerase chain reaction) detection of HPAI H5 clade 2.3.4.4b in a dairy cattle herd in Oregon.
APHIS will complete genetic sequencing and announce final results as soon as they are available. The affected herd was tested as part of Oregon's ongoing surveillance for HPAI in dairy cattle. Prior to this detection, the herd has consistently tested negative through routine surveillance conducted under the National Milk Testing Strategy program.
This marks the first reported case of HPAI in cattle in Oregon. While dairy cattle in a total of 22 states have been infected since the start of the outbreak in March 2024, APHIS has seen cases in previously unaffected states this year. APHIS is working closely with the Oregon Department of Agriculture to conduct additional on-farm investigations, diagnostic testing, and epidemiological data collection to better understand the detection and prevent further disease spread.
The detection does not change USDA’s HPAI eradication strategy. Biosecurity is still key to mitigating the risk of disease introduction or spread between premises. APHIS recommends enhanced biosecurity measures for all dairy farms. Producers should immediately report any livestock with clinical signs, or any unusual sick or dead wildlife, to their state veterinarian.
This detection does not pose a risk to consumer health or affect the safety of the commercial milk supply. The U.S. Food and Drug Administration is confident that pasteurization is effective at inactivating HPAI virus, and that the commercial, pasteurized milk supply is safe. Dairies are required to send only milk from healthy animals into processing for human consumption; milk from impacted animals is being diverted from the commercial milk tank or destroyed so that it does not enter the human food supply.
According to the U.S. Centers for Disease Control and Prevention (CDC), HPAI viruses circulating in birds and U.S. dairy cattle pose a low risk to the general public in the United States. However, people who have job-related or recreational exposures to infected birds or mammals are at higher risk of infection and should take appropriate precautions outlined in CDC guidance.
