Mexico’s youngest confirmed H5N1 case raises concern

Mexico has recorded its first human case of H5N1 avian influenza, also known as bird flu, the country’s health ministry announced Friday. The disease was found in a 3-year-old girl from the northern Durango state, who is seriously ill and hospitalized.

The health ministry reaffirmed that there is no current evidence to suggest persistent human-to-human transmission of the virus. The World Health Organization has stated that the risk to the general public is low.

H5N1, a highly pathogenic strain of avian influenza, has spread globally in animals since 2020, causing extensive outbreaks in commercial poultry and sporadic incidence in other animals, including alpacas and household cats. In 2024, for the first time, the virus was detected in cattle.

According to Reuters, Durango’s economy, which is particularly reliant on cattle-based agriculture, is particularly vulnerable to such outbreaks. 

This recent human case is a new landmark in Mexico’s avian influenza history. The World Health Organization notes that Mexico also had its first confirmed human case of A(H5N2) avian flu last year, which killed a 59-year-old patient who had underlying conditions. Notably, the case had no reported exposure to poultry or animals, leaving the virus’s transmission dynamics in doubt.

As a result of these cases, public health officials have tightened surveillance and prevention interventions. These include monitoring individuals who had close contact with infected individuals, such as active investigations to identify the source of the virus. Health experts are also scaling up diagnostics and response to any future outbreaks.

While these isolated cases continue to be a cause for concern, WHO’s assessment is that the risk of a wider, sustained outbreak is low. No additional human cases of the H5N2 strain have been detected, and no further transmission has been found in the communities where the cases occurred.

Authorities are maintaining heightened vigilance within poultry and wild bird populations, where H5N1 continues to pose a risk. Health authorities recommend increased alertness, especially in areas of confirmed outbreaks, and urge travelers to avoid contact with poultry or contaminated environments in those countries.

Although this case does not change the general risk to the broader population, health organizations are watching the situation closely, given the variability of influenza viruses and their potential to perhaps spark larger outbreaks.