HPAI detection in Washington dairy herds turns biosecurity into a shared supply-chain task

The confirmation of highly pathogenic avian influenza in two Washington State dairy herds again puts biosecurity at the centre of animal-production chains as a cross-species discipline. On 8 October, USDA’s Animal and Plant Health Inspection Service reported PCR detection of H5 virus from clade 2.3.4.4b. Genetic sequencing is still to be completed.

According to APHIS, these are the first confirmed livestock detections in Washington. The affected herds were tested after showing clinical signs consistent with avian influenza and had previously tested negative under routine surveillance within the National Milk Testing Strategy. The agency and the Washington Department of Agriculture are conducting further epidemiological investigations, diagnostic testing and data collection.

The official announcement does not change the U.S. eradication strategy. APHIS stresses that biosecurity remains the principal measure for reducing introduction and spread between premises. It also states that milk from affected animals is diverted from the commercial tank or destroyed, and that commercially pasteurised milk is considered safe.