International experts are sounding the alarm about mutations of the H5N1 avian flu virus in the United States and possible transmission to humans.
- The H5N1 avian flu virus, which appeared in 1996, is spreading to new species and regions, sparking fears of a pandemic. Since 2021, it has caused the slaughter of 300 million poultry and infected 315 bird species.
- It now also affects mammals and has contaminated dairy cows in the United States, where 58 human cases have been recorded in 2023. A recent study found that 7% of dairy workers tested in Michigan and Colorado had antibodies against H5N1.
- According to researchers, the virus is one mutation away from spreading more easily between humans. The WHO calls for increased vigilance in the face of this risk.
Since its appearance in 1996 in China, the H5N1 avian flu virus has continued to cross new boundaries, infecting an increasing number of animal species and spreading to previously unspoilt regions, such as Antarctica. If this health crisis has mainly affected birds so far, recent signs worry scientists about potential increased human transmission.
An alarming spread of bird flu
According to the World Organization for Animal Health (WHOA), more than 300 million poultry have been culled due to avian flu since 2021, and the virus has infected 315 species of wild birds in 79 countries. This toll is increasing with cases detected in mammals, such as seals, having consumed infected dead birds. Last March, a major milestone was reached: herds of dairy cows in the United States were contaminated, raising fears about a possible adaptation of the virus to mammals. At the end of October, a pig was infected in Oregon before being slaughtered – an animal known to promote recombination between different influenza viruses including human flu, and therefore increase the risk of emergence of a pandemic strain.
Humans are not spared. This year, 58 cases of bird flu have been confirmed in the United States, including two in people who had no direct contact with infected animals. A recent study found that 7% of dairy workers tested in Michigan and Colorado had antibodies to H5N1. “Bird flu is knocking on our door and could trigger a new pandemic”says epidemiologist Meg Schaeffer to AFP.
The H5N1 virus has a mutation to become pandemic
Currently, several barriers prevent H5N1 from being transmitted effectively between humans, such as difficulty infecting the lungs. However, recent research indicates that the strain that infected American cows is now just one mutation away from increased spread in humans. For Ed Hutchinson, virologist at the University of Glasgow, “The H5N1 virus is just one step away from becoming more dangerous for us”. Recent genetic sequencing of a seriously affected Canadian teenager even revealed adaptations of the virus to better colonize human cells. However, as Hutchinson points out, “We do not yet know whether the virus will evolve into a human disease.”
The scientific community remains unanimous: the more animal species H5N1 infects, the greater the risk of adaptation to the human body. A bird flu pandemic would be particularly serious, as humanity does not have natural immunity against this virus. While human cases recorded so far have been mild in the United States, it is crucial to note that nearly 50% of the 904 human cases recorded since 2003 have been fatal, according to the WHO. Maria Van Kerkhove, head of the epidemic prevention department at the UN health agency, calls for “redouble your vigilance” while the shadow of a pandemic looms.
