A small portion of the virus found in a patient's throat has genetic changes that could result in “increased virus binding,” health authorities revealed Thursday.
The first serious human case of avian flu in the United States carries a virus that may have mutated inside its body to adapt to human respiratory tract, American health authorities announced Thursday. The American Centers for Disease Prevention and Control (CDC) announced on December 18 that an elderly patient was hospitalized in Louisiana in “a critical condition” after being contaminated by the H5N1 virus.
A small part of the virus found in this patient's throat has genetic modifications that could result in “increased virus binding” with some “human upper respiratory tract cell receptors”the CDC revealed Thursday. They have “probably were generated during virus replication in the patient”indicated the CDC, specifying that no transmission of this mutated virus has been identified.
These changes have not been observed in contaminated birds, including those with which the patient may have been in contact in a farmyard. Experts contacted by AFP said it was too early to determine whether these changes could allow the virus to spread more easily, or cause more serious cases in humans.
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“Infect the upper respiratory tract”
The mutation in question constitutes “a necessary step for a virus to become more contagious”explained to AFP Angela Rasmussen, virologist at the University of Saskatchewan, in Canada. “But I insist on the fact that it is not the only one” necessary, she added. Angela Rasmussen said the mutation could make it easier for the virus to enter cells, but further testing will need to be done in animals to confirm this. Genetic modifications have already been observed in the past in seriously ill patients infected with avian flu, but have not yet resulted in an increase in the transmissibility of the virus to humans.
For Thijs Kuiken of the Erasmus University Medical Center in the Netherlands, these changes could lead to less serious infections, with the virus becoming «plus susceptible» d’“infect the upper respiratory tract”causing runny nose or sore throat, affecting the lower respiratory tract, and leading to pneumonia. These observations therefore do not mean that we are getting closer to a “pandemic”insisted Angela Rasmussen.
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. 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.
