Influenza A(H5N1) Virus Infection in Two Dairy Farm Workers in Michigan

This correspondence describes two confirmed cases of highly pathogenic avian influenza (HPAI) A(H5N1) virus infection in dairy farm workers in Michigan, following outbreaks among lactating cows across 13 U.S. states. Worker MI-A developed conjunctivitis after milk splashed into the eye; RT-PCR testing of conjunctival swabs confirmed HPAI A(H5N1) clade 2.3.4.4b (genotype B3.13). Worker MI-B presented with respiratory symptoms after direct contact with sick cows and oral secretions; nasopharyngeal swabs tested positive for HPAI A(H5N1). Both cases underscore zoonotic transmission risks from infected cattle, especially via ocular and respiratory exposure. The report highlights diagnostic challenges, variable symptom presentation, and the importance of personal protective equipment (PPE). It calls for heightened surveillance, protective protocols, and further investigation into mammalian adaptation of avian influenza viruses.

This correspondence describes two confirmed cases of highly pathogenic avian influenza (HPAI) A(H5N1) virus infection in dairy farm workers in Michigan, following outbreaks among lactating cows across 13 U.S. states. Worker MI-A developed conjunctivitis after milk splashed into the eye; RT-PCR testing of conjunctival swabs confirmed HPAI A(H5N1) clade 2.3.4.4b (genotype B3.13). Worker MI-B presented with respiratory symptoms after direct contact with sick cows and oral secretions; nasopharyngeal swabs tested positive for HPAI A(H5N1). Both cases underscore zoonotic transmission risks from infected cattle, especially via ocular and respiratory exposure. The report highlights diagnostic challenges, variable symptom presentation, and the importance of personal protective equipment (PPE). It calls for heightened surveillance, protective protocols, and further investigation into mammalian adaptation of avian influenza viruses.