The World Health Organization (WHO) announced on Wednesday that a 59-year-old resident of Mexico had succumbed to a subtype of avian influenza, marking the first confirmed human fatality from the H5N2 strain of bird flu. This case, a global first, underscores the evolving threats posed by zoonotic diseases.
The deceased individual, who passed away on April 24, exhibited symptoms including fever, shortness of breath, diarrhea, nausea, and general discomfort before being hospitalized at the National Institute of Respiratory Diseases in Mexico City. Despite medical intervention, the patient died on the same day.
Remarkably, the WHO reported that the patient had no known history of exposure to poultry or other animals, which are typical vectors for bird flu transmission. This is particularly concerning given that the H5N2 strain had only been detected in poultry in Mexico prior to this case. The WHO emphasized that the patient had multiple underlying health conditions, including chronic kidney disease, type 2 diabetes, and long-term systemic arterial hypertension, and had been bedridden for three weeks before the onset of acute symptoms.
Despite the severity of this case, health authorities have sought to reassure the public. The WHO noted that the risk of human-to-human transmission remains low. "While a human infection with bird flu has the potential for high public health impact, the current risk to the general population is low," the WHO stated.
The Mexican Ministry of Health echoed these sentiments, emphasizing in a statement that there is no identified source of infection, thus minimizing the risk of contagion for the broader population. The ministry confirmed that all samples from identified contacts of the patient tested negative for the H5N2 virus.
Following the patient's death, health officials conducted an extensive investigation, identifying 17 hospital contacts and 12 additional contacts near the patient's residence. Among these, only one individual reported mild symptoms, which subsequently tested negative for bird flu and COVID-19. Further, nasal, throat, and blood samples from these contacts were analyzed, with no additional cases of H5N2 detected to date.
Dr. John Brownstein, an epidemiologist and chief innovation officer at Boston Children's Hospital, underscored the significance of this case. "While both H5N2 and H5N1 belong to the same family of influenza A viruses, H5N1 has been known to infect humans for years, whereas this is the first-ever reported case of H5N2 in humans," he noted. "The good news is that neither H5N2 nor H5N1 have demonstrated human-to-human transmission so far. However, this first case is a wake-up call. It reminds us that influenza viruses can evolve, and continued surveillance of these viruses in both animals and humans is crucial."
The emergence of the H5N2 strain in humans draws attention to the broader context of avian influenza outbreaks. In the United States, the H5N1 strain has caused significant concern, affecting millions of birds and several dairy cows. So far, three farmworkers in the U.S. have contracted the H5N1 virus, all experiencing mild symptoms and subsequently recovering.
The Centers for Disease Control and Prevention (CDC) in the U.S. has also reassured the public regarding the low risk of widespread transmission. "There is no evidence of human-to-human transmission of these strains," the CDC stated.
