University of Nebraska Medical Center

Highly Pathogenic Avian Influenza A(H5N1) Virus Infection in a Dairy Farm Worker


Sporadic human infections with highly pathogenic avian influenza (HPAI) A(H5N1) virus, with a wide spectrum of clinical severity and a cumulative case fatality of more than 50%, have been reported in 23 countries over more than 20 years.1 HPAI A(H5N1) clade viruses have spread widely among wild birds worldwide since 2020–2021,2,3 resulting in outbreaks in poultry and other animals.2 Recently, HPAI A(H5N1) clade viruses were identified in dairy cows, and in unpasteurized milk samples, in multiple U.S. states.4,5 We report a case of HPAI A(H5N1) virus infection in a dairy farm worker in Texas.

In late March 2024, an adult dairy farm worker had onset of redness and discomfort in the right eye. On presentation that day, subconjunctival hemorrhage and thin, serous drainage were noted in the right eye. Vital signs were unremarkable, with normal respiratory effort and an oxygen saturation of 97% while the patient was breathing ambient air. Auscultation revealed clear lungs. There was no history of fever or feverishness, respiratory symptoms, changes in vision, or other symptoms. The worker reported no contact with sick or dead wild birds, poultry, or other animals but reported direct and close exposure to dairy cows that appeared to be well and with sick cows that showed the same signs of illness as cows at other dairy farms in the same area of northern Texas with confirmed HPAI A(H5N1) virus infection (e.g., decreased milk production, reduced appetite, lethargy, fever, and dehydration5). The worker reported wearing gloves when working with cows but did not use any respiratory or eye protection.

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