In an unprecedented case reported on 23rd May 2024, the Mexico International Health Regulations (IHR) National Focal Point announced a confirmed instance of avian influenza A(H5N2) in a human. The afflicted individual was a 59-year-old resident of the State of Mexico with no recorded contact with poultry or other animals. The patient, suffering from multiple underlying medical conditions, half confirmed to be bedridden for other reasons three weeks before developing severe symptoms.
On 17 April, the patient exhibited multiple symptoms – fever, shortness of breath, diarrhoea, nausea and general malaise. By 24 April, the patient had sought medical attention and was admitted to the National Institute of Respiratory Diseases “Ismael Cosio Villegas”. Unfortunately, the patient passed away the same day due to further health complications.
The patient’s samples were collected on 24 April at the Institute and Real-Time Polymerase Chain Reaction (RT-PCR) suggested the presence of a non-subtypeable influenza A virus. After subsequent sequencing at the Center for Research in Infectious Diseases (CIENI), it became apparent on 8 May that the sample had tested positive for virus A(H5N2). Furthermore, on 22 May, the sample was successfully sequenced at the Institute of Epidemiological Diagnosis and Reference, reinforcing the positive result for influenza A(H5N2). No additional cases were reported during the epidemiological investigation.
In total, 17 hospital contacts were monitored, one of whom exhibited symptoms of a mild runny nose later in April. However, tests run between 27 and 29 May confirmed negative results for both influenza and SARS-CoV 2.
Close to the patient’s place of residence, an additional 12 contacts were found (seven symptomatic and five asymptomatic). Physical samples were subsequently collected and tested negative for SARS-CoV-2, influenza A and B.
March 2024 had registered two distinct outbreaks in Michoacán and the State of Mexico, both involving the avian influenza A(H5N2). A study published in 2022 had indicated a recurring pattern of animal influenza infecting humans, generally via direct contact with infected animals or contaminated surroundings.
As a result of this incident, localized and national health institutions have taken appropriate public health measures, promoting the use of antiviral drugs to reduce viral replication duration and improving survival chances for affected cases. Despite this being the first lab-confirmed human A(H5N2) virus infection, experts speculate that the ongoing investigation might link its source to similar poultry outbreaks in Mexico.
Presently, the World Health Organization (WHO) considers the general risk level for the populace to be low. However, continuous surveillance of influenza nerve centers is advised for early detection of any concerning epidemiological, virological or clinical patterns.
Source: https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON520