WHO Reports First Human Fatality from H5N2 Bird Flu in Mexico

The World Health Organization (WHO) has recently announced a significant health event: the first confirmed human fatality attributed to the avian influenza A H5N2 virus, marking a concerning milestone in the history of infectious diseases. This incident, reported in Mexico, represents the first global instance of a human infection with the H5N2 strain of bird flu, as confirmed through laboratory testing.

The case was initially brought to the attention of the Pan American Health Organization (PAHO) and WHO by the Mexico International Health Regulations National Focal Point (IHR NFP) on May 23, 2024. The patient, a 59-year-old resident of Mexico City, was admitted to a hospital with no known history of contact with poultry or wildlife. Despite this, the individual succumbed to complications arising from multiple underlying health conditions, exacerbated by the viral infection.

Medical records reveal that the patient had been bedridden due to unrelated health issues for three weeks before developing symptoms associated with the H5N2 infection on April 17. These symptoms included fever, shortness of breath, diarrhea, nausea, and general malaise. The patient sought medical help on April 24 and was subsequently hospitalized at the National Institute of Respiratory Diseases "Ismael Cosio Villegas" (INER), where he passed away on the day of admission.

Diagnostic tests conducted at INER initially identified a non-subtypeable influenza A virus through Real-Time Polymerase Chain Reaction (RT-PCR) analysis of a respiratory sample. Further investigation by the Laboratory of Molecular Biology of Emerging Diseases at INER's Center for Research in Infectious Diseases (CIENI) confirmed the presence of the influenza AH5N2 virus on May 8. The diagnosis was corroborated by additional RT-PCR analysis and sequencing at the Institute of Epidemiological Diagnosis and Reference (InDRE) of the Mexico National Influenza Centre, which also confirmed the AH5N2 subtype on May 22.

Following an extensive epidemiological investigation, no additional cases of H5N2 infection were identified. Bird flu viruses, including H5N2, primarily affect birds but have been known to infect humans. Human cases can range from mild to severe respiratory symptoms and can include conjunctivitis and gastrointestinal issues. These viruses typically spread through direct contact with infected animals or contaminated environments.

This incident underscores the importance of vigilant monitoring and reporting systems for infectious diseases worldwide. It also highlights the potential for animal viruses to infect humans, emphasizing the need for ongoing research and preparedness to address emerging infectious diseases.