Public Health France has just published a point position epidemiology on the circulation of avian influenza viruses and recalls the recommendations to follow in the event of risky exposure. As a reminder, humans can be infected by several avian influenza viruses, in particular the H5N1, H7N9 and H9N2 subtypes.
An unprecedented epizootic
Since October 2021, Europe has been suffering the most devastating outbreak of highly pathogenic avian influenza it has ever known. At the global level, almost all continents are affected (in particular Europe, Asia, the Americas and to a lesser extent Africa).
In France, since August 2022, more than 300 outbreaks have been detected on farms (more than three quarters in the Pays de la Loire region). Among wild birds, the number of cases also increased sharply in France in 2022-2023: hundreds of infected birds were found dead on the territory.
Infected mammals
The intense and continuous circulation of these viruses in birds has led to their introduction into some twenty species of terrestrial and marine mammals, wild and domestic. Worldwide, hundreds of infected mammals have been found dead or on the verge of death, often with neurological damage. Transmission between mammals has been mentioned several times. In France, a cat was infected at the end of December 2022 in Deux-Sèvres, the origin of the contamination being a neighboring duck farm. The first analyzes did not reveal any acute infection among the people exposed to this cat, but additional serological analyzes are in progress.
What are the risks for humans?
The World Health Organization (WHO) considers that the risk of transmission to humans of the currently circulating avian influenza viruses is low and no human-to-human transmission has been documented. Several detections of the A(H5N1) virus or the H5Nx subtype belonging to clade 2.3.4.4b have been confirmed in humans since the end of 2021 (no cases in France) but this number remains low given the intensity of the outbreak. global epizootic. However, the fact that these viruses increasingly infect mammals of various species increases the risk of emergence of a new influenza virus better adapted to humans and capable of human-to-human transmission.
In humans, the clinical forms can be mild or even asymptomatic but also severe with admission to intensive care and death.
How to protect yourself?
In the event of contact or risky exposure to wild or domestic animals, Public Health France recommends:
- Do not touch dead or injured animals: notify the Departmental Office for Biodiversity or the Federation of Hunters and inform the town hall;
- Protect yourself (gloves, mask, hand washing) in the event of contact with wild birds, for example when collecting dead wild birds or during occupational exposure to birds suspected of infection;
- Get vaccinated every year once morest seasonal influenza when you are a professional exposed to swine and avian influenza viruses, in order to avoid simultaneous infection by an avian or swine influenza virus and a human influenza virus, this which might lead to the emergence of a new influenza virus contagious to humans;
- Consult immediately in case of symptoms (fever, cough, fatigue, breathing difficulties, neurological disorders) within 10 days of exposure to risk (contact with wild or domestic birds, with sick or dead wild mammals, or even pigs with the flu ).
It is important to remember that health professionals are required to immediately report any suspected case of zoonotic influenza to the health authorities in order to put in place appropriate management measures.