First cases of highly pathogenic avian influenza in dairy cows in Washington State
The first cases of bird flu in dairy cattle have been confirmed in Washington state, according to the USDA. The HPAI H5 clade 2.3.4.4b virus has been detected in 2 dairy herds.
The US Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) National Veterinary Services Laboratories (NVSL) confirmed highly pathogenic avian influenza (HPAI) H5 clade 2.3.4.4b in 2 dairy cattle herds in Washington. This was announced on 8 October.
APHIS will complete genetic sequencing and announce final results as soon as they are available. The affected herds were tested after exhibiting clinical signs consistent with avian influenza. Prior to this detection, the herds consistently tested negative through routine surveillance conducted under the National Milk Testing Strategy program.
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First cases in Washington State
These are the first confirmed case detections of HPAI in livestock in the State of Washington. While dairy cattle in a total of 19 states have been infected since the start of the outbreak in March 2024, APHIS has seen cases in only a small number of states this year.
It is working closely with the Washington 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.
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Biosecurity
USDA’s HPAI eradication strategy is a top priority and biosecurity is still key to mitigating the risk of disease introduction or spread between premises, says the USDA. 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. Financial assistance is available to enhance biosecurity and offset costs associated with HPAI.
This detection does not pose a risk to consumer health or affect the safety of the commercial milk supply. According to the US Centers for Disease Control and Prevention (CDC), highly pathogenic avian influenza viruses circulating in birds and US dairy cattle pose a low risk to the general public in the United States.