In other words, even if this new variation of the H5N1 avian flu, which has infected dozens of million birds on four continentsne touch only birds, the fact that it circulates so widely increases the risk that at some point a group of this virus will have undergone a mutation that makes it capable of being transmitted to humans. This is why the same basic advice has been heard so often in recent days: do not touch a dead bird without gloves.
By the numbers: Since October, this strain of H5N1 has caused about 3,000 outbreaks in poultry farms in dozens of countries—the first case reported in Quebec was in april. More than 77 million animals were euthanized to limit the risk of spreading the virus. There are 400,000 dead wild birds. Although this number is surely below the reality, it’s already a lot more than the last major wave of avian flu, in 2016-2017. Which was itself only the sequel to this H5N1 detected for the first time in 1996 in geese in Asia, then in poultry in Europe and Africa in the 2000s. It is since 2005 that we observe intermittent waves of deaths among wild birds, according to their migrations. And the more contagious lineage we’re talking about now — called 2.3.4.4 — was first observed in 2014.
If this return this year has what worry them poultry farmers, it is the wild bird as a vector of transmission that worries scientists. Because unlike farmed birds, we cannot contain them and even less euthanize them en masse. At most, we can see that certain species, such as the barnacle goose, in Norway last winter, seem more vulnerable than others, which, in theory, would perhaps make it possible to issue preventive alerts when it s These are migratory species passing through a region.
The first documented case of a human infected with this new strain dates back to December, in Great Britain: it was a pensioner who raised ducks. In April, the state of Colorado reported a first case in North America in a slaughterhouse worker. The cases were mild, but “these viruses are like ticking time bombs”, declare in the magazine Nature the deputy director of the WHO Center for Influenza Research. “Occasional infections are not a problem: it is the gradual gain in function of these viruses” that constitutes the real problem, that is to say their capacity, one mutation at a time, to be transmitted more easily between birds. Or, worse, between humans.