Analysis on H5N1 Subtype HPAI Outbreaks in Dairy Cattle in the United States in 2024
Since March 2024,several cases of dairy cattle infected with H5N1 subtype high pathogenicity avian influenza virus(HPAIV)were reported in the United States,causing extensive global concern.In the paper,the outbreak was systematically reviewed,its prevalence and distribution rule were analyzed,and recommendations on measures to prevent the risk were proposed.It was found that,based on current data,the responsible H5N1 subtype HPAIV was classed into the clade 2.3.4.4b,and highly homologous to the strain synchronously prevalent in poultry and wild birds in the United States.Preliminary analysis revealed that the responsible virus might originate from wild migratory birds.Since the outbreak,comprehensive prevention and control measures including movement restriction and transportation inspection were taken by the United States where the dairy industry might be imposed with negative impact to a certain degree,but China had been less affected till now.Therefore,it was recommended to reduce potential impact to China through continuously monitoring the outbreaks outside of China,strengthening risk surveillance on domestic wild birds,implementing compulsory immunization to poultry,intensifying publicity and guidance,and improving emergency reserves,etc.