Mexico - PAHO: Human H5N1 case - September 30, 2025

[Shiloh]

Source: https://www.paho.org/en/documents/ep...5-october-2025

Epidemiological Update Avian Influenza A(H5N1) in the Americas Region - 15 October 2025

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In recent years, there has been an increase in the detection of A(H5N1) viruses in non-avian species worldwide, including terrestrial and marine mammals, both wild and domestic (companion and production). Since 2022, twenty-two countries on three continents, including the Americas, have reported outbreaks in mammals to the World Organization for Animal Health (OIE). Historically, from early 2003 to August 25, 2025, 990 human cases of avian influenza A(H5N1) were reported to the World Health Organization (WHO), including 475 deaths (48% fatality rate), in 25 countries worldwide. Since 2022 and as of epidemiological week 41 of 2025, a total of 19 countries and territories in the Americas Region reported 5,063 outbreaks of avian influenza A(H5N1) to WOAH. Between 2022 and 14 October 2025, a total of 76 human infections caused by avian influenza A(H5), including two deaths, have been reported in five countries in the Americas.

[sharon sanders]

Source: https://www.paho.org/en/documents/ep...5-october-2025

Epidemiological Update Avian Influenza A(H5N1) in the Americas Region - 15 October 2025

Download

In recent years, there has been an increase in the detection of A(H5N1) viruses in non-avian species worldwide, including terrestrial and marine mammals, both wild and domestic (companion and production). Since 2022, twenty-two countries on three continents, including the Americas, have reported outbreaks in mammals to the World Organization for Animal Health (OIE). Historically, from early 2003 to August 25, 2025, 990 human cases of avian influenza A(H5N1) were reported to the World Health Organization (WHO), including 475 deaths (48% fatality rate), in 25 countries worldwide. Since 2022 and as of epidemiological week 41 of 2025, a total of 19 countries and territories in the Americas Region reported 5,063 outbreaks of avian influenza A(H5N1) to WOAH. Between 2022 and 14 October 2025, a total of 76 human infections caused by avian influenza A(H5), including two deaths, have been reported in five countries in the Americas.

The most recent case of human infection with avian influenza A(H5) reported in the Americas Region was recorded in Mexico on 2 October 2025

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the most recent case of human infection was confirmed in Mexico on 30 September 2025 (6, 7), in addition to the case reported in Mexico on 2 April 2025.

Below is a summary of the second human case of influenza A(H5) reported in Mexico in 2025. On 2 October 2025, Mexico's International Health Regulations (IHR) National Focal Point (NFP) notified PAHO/WHO of a laboratory-confirmed human infection caused by avian influenza A(H5) virus in Mexico City, the second confirmed human case in the country in 2025 (6, 7). The case corresponds to a 23-year-old female with no history of seasonal influenza vaccination or recent travel (6, 7). On 14 September 2025, she developed respiratory symptoms, including rhinorrhea and cough. Between 21 and 28 September, she developed fever and odynophagia, followed by hemoptysis and chest pain, and was hospitalized at the National Institute of Respiratory Diseases (INER per its acronym in Spanish). On 29 September, a bronchoalveolar lavage sample was taken, which tested positive for unsubtypeable influenza A. On 30 September, the presence of influenza A(H5) virus was confirmed by real-time RT-PCR. The case was treated with oseltamivir and discharged on 11 October. The sequencing result shows the presence of an avian influenza A(H5Nx) virus. During the epidemiological investigation, 41 contacts were identified. Samples were taken from the identified contacts and they were given oseltamivir prophylaxis. All samples collected were negative for avian influenza (6, 7). A dog was identified as a pet at the case’s residence, and several animals were found in the courtyard of the building, including a poultry bird and two pigeons, as well as bird droppings in several areas, including in a poorly sealed cistern that supplies water to all the apartments in the building. Samples were collected from the identified animals and analyzed by the Official Laboratory of the National Service for Agrifood Health, Safety, and Quality (SENASICA, per its acronym in Spanish), and tested positive for influenza A(H5). Environmental samples were also collected and are still being analyzed, as of the time of publication (6, 7).

[sharon sanders]

Please see:

Mexico - Avian flu in wild & domestic birds - 2025