Fatal H5N2 Bird Flu Case Confirmed in Mexico

The World Health Organization (WHO) has confirmed the first laboratory-verified human case of avian influenza A(H5N2) globally, reported in Mexico. This significant development, announced on June 5, 2024, marks a critical moment for global health surveillance, as reported by Reuters.

www.reuters.com reported, The patient, a 59-year-old male residing in Mexico State, tragically died on April 24, 2024, after experiencing a rapid onset of symptoms. According to the WHO, he had several pre-existing medical conditions, complicating his health status.

Crucially, Mexican health authorities and the WHO noted that the patient had no documented history of exposure to poultry or other animals. This absence of direct contact has intensified investigations into the source of infection, as stated by the Secretaría de Salud de México.

www.reuters.com noted, Investigations are currently underway to determine how the individual contracted the virus. The WHO confirmed that contact tracing efforts have identified no further human cases linked to this patient, suggesting no immediate evidence of human-to-human transmission.

Despite the fatality, the WHO has assessed the current risk to the general public from H5N2 as low. However, the organization emphasizes the ongoing need for vigilance and robust surveillance systems worldwide, as detailed in their official statement on May 29, 2024.

www.reuters.com reported, This case underscores the persistent threat of avian influenza viruses to human health and the importance of international collaboration in monitoring emerging pathogens. Experts are closely watching for any signs of viral adaptation or increased transmissibility, Reuters reported.

• Background of H5N2 Avian Influenza: Avian influenza A(H5N2) is a subtype of bird flu virus that primarily affects poultry and wild birds. While it has caused significant outbreaks in animal populations, particularly in Mexico and other parts of the world, human infections have been exceedingly rare. The virus can lead to severe disease in birds, often necessitating culling to prevent further spread, as documented by the World Organisation for Animal Health (WOAH).
• Patient Profile and Timeline: The deceased patient was a 59-year-old male with multiple underlying health conditions, including chronic kidney disease, type 2 diabetes, and systemic arterial hypertension, according to Mexico's Ministry of Health. He developed symptoms such as fever, shortness of breath, diarrhea, and nausea on April 17, 2024, and was hospitalized in Mexico City before his death on April 24, 2024, as detailed by the WHO.
• Ongoing Investigation and Source of Exposure: The precise source of the patient's infection remains unknown, prompting an intensive epidemiological investigation. Mexican health authorities, in collaboration with the WHO, are conducting contact tracing, environmental sampling, and genetic sequencing of the virus to identify the origin. The lack of direct poultry exposure makes understanding the transmission pathway particularly challenging, Reuters noted.
• Risk Assessment and Public Health Implications: The WHO maintains that the current risk to the general population from H5N2 is low, emphasizing that this is an isolated case without evidence of sustained human-to-human transmission. However, any human infection with an avian influenza virus is a public health concern due to the potential for viral mutation and adaptation, highlighting the need for continuous global surveillance, as stated by WHO officials.
• Comparison with Other Avian Flu Strains: While H5N2 is less commonly associated with human infections, other avian influenza strains like H5N1 have caused hundreds of human cases globally since 2003, often with high fatality rates. H5N1 has also recently spread to mammals, including dairy cattle in the United States. This H5N2 case serves as a reminder that various avian flu subtypes pose a potential zoonotic threat, according to CDC reports.
• H5N2 in Mexican Poultry: Mexico has a history of H5N2 outbreaks in its poultry industry. SENASICA, Mexico's National Service for Agrifood Health, Safety and Quality, reported H5N2 outbreaks in poultry farms in the State of Mexico in March 2024. This indicates the virus's circulation in the region's animal population, providing a potential environmental context for the human case, though a direct link is yet to be established.
• Global Surveillance and Preparedness: This case underscores the critical importance of robust global surveillance systems for avian influenza viruses in both animal and human populations. International health organizations and national governments are urged to enhance their preparedness plans, including rapid diagnostic capabilities, vaccine development, and public health communication strategies, as emphasized by the WHO.