The information could have been drowned in scientific publications. But in the midst of a coronavirus epidemic, the discovery by Chinese researchers of a new strain of swine flu in China takes a whole different turn. Likely to create, according to them, a "pandemic", this virus shows a high adaptability "to infect humans". Should we worry about it? Specialists remain cautious.
Swine flu left its mark in 2009. The virus had killed several hundred people in Mexico, and 30,000 cases had been identified in more than 70 countries. Given the scale of the epidemic, WHO had qualified the situation as a “pandemic” on June 11, 2009. And it is the same strain, which descends genetically from that of H1N1, that scientists have still identified in China .
" It is not the first time "
Are we following the same path, more than ten years later? "It should be remembered that in 2009 it was a flu that brought together several origins, not just swine," tempers Jeanne Brugère Picoux, honorary professor of the National Veterinary School of Alfort.
As defined by the World Organization for Animal Health (OIE), swine flu is "a highly contagious viral infection of swine. The disease generally spreads very quickly in farms without all infected pigs showing clinical signs of infection. Infected pigs then recover quickly. ” According to specialists, the disease is common. "There is always," confirms to Parisian Vincent Enouf, deputy director of the National Reference Center for Influenza at the Pasteur Institute. "There is no reason to worry. It is not the first time that a pig epidemic has been announced. It makes sense because pork and humans are sensitive to the same viruses, ”continues Jeanne Brugère Picoux.
No inter-human transmissions
Most swine flu viruses, however, are not pathogenic to humans, according to the World Health Organization (WHO). “However, some countries have reported human infection with these viruses. Most were mild and the viruses did not spread to other people later, ”she said. This is for example the case in China. Indeed, if American researchers found in workers and people working with pigs a high proportion of infected people: 10.4%, there is no evidence that the virus can be transmitted from human to human.
“There is no evidence of human-to-human transmission. It underlines the interest of monitoring these farms, in which the virus seems to circulate more. And be vigilant in these regions if the flu circulates. But this point is missing in the article, ”underlines Vincent Maréchal, virologist. “Pigs can harbor chimeric viruses from other strains of influenza. These new viruses can be problematic because they can then be adapted to humans and be prepandemic. It is therefore quite normal for this monitoring to take place. This is also due to the history of influenza pandemics that often start from China, "said the professor.
"After the coronavirus, it is logical that the Chinese say to monitor their pig farming, because it is a zoonosis that happened for Covid, a transmission from animal to man. And especially when you know that 75% of new emerging viruses are from zoonotic influenza viruses. But for the moment these researchers have carried out the work of an epidemiologist who has not shown his installation in humans, ”says Jeanne Brugère Picoux.
