American health authorities announced on December 18 that an elderly patient suffering from other pathologies was hospitalized in “critical condition” in Louisiana after contracting avian flu, a first in the country.
After the detection of a first serious case of avian flu in humans and new contaminations in felines, the spread of the H5N1 virus is causing concern in the United States, although experts are refusing to give in to panic.
American health authorities announced on December 18 that an elderly patient suffering from other pathologies was hospitalized in “a critical condition” in Louisiana after contracting bird flu, a first in the country.
“Worrying mutations”
According to sequencing released Thursday, a small part of the H5N1 virus found in this patient's throat has genetic modifications that could make it more adapted to the human upper respiratory tract (from the nose to the larynx). These mutations have “probably were generated during virus replication in the patient”indicated the American Centers for Disease Prevention and Control (CDC).
“RNA viruses are known to mutate inside their hosts, and these mutations are of course worrying”reacted to AFP Rebecca Christofferson, researcher at Louisiana State University.
More “the good news is that there does not appear to be any evidence to suggest that the virus has become more transmissible, as no other cases have been associated with this one”she tempered.
Epizootic
For several months, the United States has been facing an epizootic – the equivalent of an epidemic in animals – of avian flu. The growing number of mammals infected with the disease worries experts, who fear that high circulation could facilitate a mutation of the virus that would allow it to pass from one human to another.
In the case of the patient from Louisiana, the genetic mutations observed constitute “a necessary step for a virus to become more contagious”more “she’s not the only one” necessary, insisted to AFP Angela Rasmussen, virologist at the University of Saskatchewan in Canada.
Similar changes have already been observed in the past in seriously ill patients infected with avian flu, and have not yet resulted in an increase in the transmissibility of the virus to humans, the experts point out.
For Thijs Kuiken, from the Erasmus University Medical Center in the Netherlands, these latest genetic mutations could also lead to less serious infections, with the virus becoming «plus susceptible» d’“infect the upper respiratory tract” and therefore cause runny noses or sore throats, rather than affecting the lower respiratory tract and causing pneumonia.
Contaminated food
Apart from these genetic modifications, it is more the level of circulation of the virus that worries researchers. In addition to this Louisiana patient, 65 mild cases of the disease have been detected in humans in the United States since the start of the year, and others may have gone unnoticed, according to the CDC.
This circulation of the virus increases the probability that it will mix with that of seasonal flu, risking triggering a process similar to those which led to the flu pandemics of 1918 and 2009, according to Angela Rasmussen. Health authorities are also closely monitoring the increase in cases of bird flu among felines.
In Oregon (northwest), a cat died after consuming raw animal food, which was confirmed by analyzes to be contaminated with the H5N1 virus. Twenty felines infected with avian flu also died in a shelter in Washington state (northwest), a local animal rights association announced on Facebook.
According to Angela Rasmussen, contaminated cats could expose their owners to «risque» to contract the disease through close contact. Avian influenza A (H5N1) first appeared in 1996, but since 2020 the number of outbreaks in birds has exploded and an increasing number of mammal species have been affected.
