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World Health Organization (WHO) has confirmed the first-ever human death caused by the H5N2 strain of avian influenza. The victim, a 59-year-old resident of the State of Mexico with underlying health conditions, passed away in April after contracting the virus.
This is the first globally reported, laboratory-confirmed human case of influenza A (H5N2) virus infection and the first instance of an avian H5 virus infecting a person in Mexico. The patient had no known history of exposure to poultry or other animals.
Mexican health authorities reported the case to WHO on May 23, 2024. The individual had been hospitalised in Mexico City on April 24, 2024 and exhibited symptoms like fever, shortness of breath, diarrhoea, nausea and general discomfort. According to the officials, the laboratory test has confirmed the 59-year-old person dying of the infection.
The death has sounded alarm bells among the scientific community. As per International Health Regulations (IHR), 2005, a human infection due to novel influenza A virus subtype even has potential for high public health impact.
The man had multiple underlying medical conditions, the WHO statement highlighted. The relatives of the victim informed the authorities that the person had been bedridden for about three weeks for reasons different than what it displayed before the acute symptoms of avian flu.
The laboratory results from the person’s sample showed a non-subtypeable influenza A virus. On May 8, 2024, the sample was sent for further analysis to the Laboratory of Molecular Biology of Emerging Diseases Center for Research in Infectious Diseases, which confirmed it was positive for influenza A (H5N2).
On May 20, the sample was sent to the Institute of Epidemiological Diagnosis and Reference (InDRE) of the Mexico National Influenza Centre for RT-PCR analysis, which yielded a positive result for influenza A, the WHO said. The sample’s sequencing confirmed the influenza subtype as A (H5N2).
This virus poses a low risk to the general population, according to WHO.
The health officials identified and tested 17 other contacts who were close to the case, out of whom one reported a runny nose between April 28 and 29. However, the tests were negative for the influenza and SARS-COV-2. Twelve additional contacts (seven symptomatic and five asymptomatic) were identified near the case’s residence, the statement further said.
All of the samples tested negative for influenza A, B, and SARS-CoV-2. The results of the serology or blood serum are pending.
Earlier in March, the strain A (H5N2) outbreak was discovered in a backyard poultry farm in Michoacán, bordering State of Mexico, where the victim’s death was reported.
Later that month, another outbreak of low pathogenicity avian influenza (LPAI) of the same strain was discovered in poultry from Texcoco, State of Mexico, followed by another outbreak of the same strain in April from the municipality of Temascalapa, also in the same state.
So far, authorities have not been able to link the first human case to the poultry outbreak.
Earlier in March, Avian influenza virus type A (H5N1) was found in dairy cattle in nine states, infecting some humans who came into close contact with the animals.
In May, Australia reported the first human infection with A(H5N1), with no evidence of transmission.
In 2021, 18 herons in China died due to avian flu of strain A(H5N6) as per the United States Centers for Disease Control and Prevention.