Avian influenza virus is a zoonotic disease and a serious public health concern, with 889 cases reported across 23 countries and deaths in approximately half of the reported cases (Influenza, 2023, H5N1 Bird Flu, 2024, Avian Influenza, 2024, Anand et al., 2024). It is transmitted from birds to humans, primarily in the setting of contact with infected animals or in an environment contaminated by the feces of infected animals (Influenza, 2023, Anand et al., 2024).

The recent notification of human infection with the H5N1 avian influenza virus in Texas, reported to the World Health Organization (WHO) by the United States on April 1, 2024. This case was reported a few days after a report of a human avian influenza case from Vietnam (Avian Influenza, 2024, Anand et al., 2024). Shortly after, two case of H5N1 infection was reported in Michigan on May 22, 2024 and May 30, 2024 (Reports Second Human Case, 2024, CDC Confirms Second Human H5 Bird Flu Case in Michigan, 2024). These cases mark a pivotal moment regarding the persistence of zoonotic diseases (Avian Influenza, 2024).

The case reported in Texas State, USA, is an adult working at a dairy cattle farm who developed conjunctivitis on March 27, 2024, originating from exposure to dairy cattle presumed to be infected with the H5N1 virus. Notably, this is the first documented case of H5N1 transmission from cattle to humans in the USA, a rare host for the virus. The case was confirmed through reverse transcription-polymerase chain reaction testing by the Texas Tech University Bioterrorism Response Laboratory and Centers for Disease Control and Prevention (CDC). Despite the potential severity of the H5N1 infection, the patient experienced only conjunctivitis, received antiviral treatment, and recovered. The second case of H5N1 avian influenza was reported in a dairy worker in Michigan presenting with conjunctivitis. In this case, the nasal swab came negative for influenza, however, the eye swab sent to CDC was positive for influenza A (H5) virus. The third case of H5N1 avian influenza was also reported in a dairy worker from Michigan, presenting with cough and conjunctivitis. This case was also confirmed by CDC. So far, there is no report of person-to-person spread of H5N1 infection.