While they remain mobilized on the front lines of the Covid-19 pandemic, global health authorities are now closely monitoring another virus: H5N8.
This Saturday, Russia announced that it had detected the first case of transmission of this avian influenza virus to humans, a virus which has also been raging in farms in France since the beginning of winter.
A discovery so "important" that the World Health Organization (WHO) was immediately notified, and launched a study on the impact on public health.
What is this virus?
What are the risks ?
Explanations.
What is the H5N8 virus?
The H5N8 virus belongs to the family of influenza A viruses, which cause avian flu and are therefore mainly found in birds.
These viruses are subtypes named by the antigens that compose them, with the letters "H" and "N".
According to the Institut Pasteur, those that cause avian flu are mostly the H5, H7 and H9 subtypes.
“This infection can affect almost any species of bird, wild or domestic.
It is usually asymptomatic in wild birds, but can become highly contagious and lead to extremely high mortality in industrial chicken and turkey farms, hence its name "bird plague" or "chicken Ebola".
», Details the institute.
Avian flu, in rarer cases, can affect “other animal species such as pigs and other mammals, including humans”.
According to the WHO, humans may in particular already be infected with avian influenza viruses of the H5N1, H7N9 and H9N2 subtypes.
However, until the announcement on Saturday of contamination to humans in Russia, the H5N8 subtype was not considered transmissible to humans, as indicated in a note from the Ministry of Agriculture.
How did this H5N8 virus get transmitted to humans?
Cases of avian flu occur after direct contact with infected poultry, according to the Institut Pasteur.
In the case of H5N8 in Russia, the seven people infected were in a poultry factory in the south of the country, where an outbreak of bird flu affected the animals in December 2020, according to the Russian health agency Rospotrebnadzor.
The agency specifies that the patients “feel good” and have no complications.
Are these contaminations of humans frequent?
If this infection is confirmed, "it would be the first time that H5N8 infects humans", assures the WHO, which recalls that, generally, the transmission of avian flu to humans is a rare occurrence.
However, this virus "must be watched" because it has the potential to mutate, warns the organization.
Gwenaël Vourc'h, director of research at INRAE, specifies that these types of avian influenza viruses "are known to evolve quite rapidly".
"For H5N8, there was no transmission to humans to date, but it is in the order of the possible viral evolution," she added.
"There may have been other cases that we have not seen, especially if he has few symptoms", adds the expert, for whom the seven cases discovered in Russia could only be " the tip of the iceberg ”.
Can this virus be transmitted from human to human?
In principle, no.
If the H5N8 strain has "crossed the interspecies barrier" by being transmitted from birds to humans, "this variant of the virus is not transmitted from one person to another at the present time", assured Anna Popova, director of the Russian health agency Rospotrebnadzor, which noted the first cases of the H5N8 virus in humans.
What is the link with the cases of avian influenza reported in France?
The H5N8 strain of avian influenza is currently raging in several farms in European countries, including France: 466 outbreaks have been detected to date, and more than three million poultry have been slaughtered, which has resulted in "a marked slowdown" of the epidemic for several weeks.
The culling strategy will be maintained to limit the spread of the virus, according to the Ministry of Agriculture.
At this stage, the H5N8 avian influenza virus present in poultry in France does not present "any risk of transmission to humans", assures the government, which indicates all the same that comparisons are in progress with the virus having contaminated people in Russia.
“To date, 130 complete viral sequences have thus been obtained.
None of the analyzes carried out by ANSES (Editor's note: health security agency) showed any properties giving rise to fear of a risk of transmission to humans of the avian influenza virus present in poultry in France ”, according to a press release of the French Ministries of Agriculture and Health.
"The results of the comparison of the sequences of the Russian virus and the viruses circulating in our territory will be communicated as soon as possible", added the ministries.
The French Public Health agency and the National Reference Center for respiratory viruses, an observatory which centralizes information at the national level, "were also contacted to jointly conduct this risk analysis," said the press release.
Is there a risk of an epidemic?
According to the first data communicated by Russia, no human-to-human contamination has been detected.
There is currently no risk of an epidemic in terms of human-to-human contamination.
There remains the risk of contamination from humans to animals, which has yet to be assessed.
The Russian state laboratory Vektor, at the origin of the discovery, estimated that it is necessary today to begin to develop a system of test which will make it possible to quickly detect the cases of this disease in the man ”and to "Start work" for a vaccine.
Morning essentials newsletter
A tour of the news to start the day
Subscribe to the newsletterAll newsletters
For its part, the World Health Organization claims "to be in discussion with the (Russian) authorities to gather more information and assess the impact of this event on public health".
For the organization, the circulation of certain variants of avian influenza in poultry in the world is "of concern for public health", because they are able to "cause serious diseases in humans" which have "little or no of immunity against the virus ”.