As per US News, tests conducted on a man infected with avian influenza in Chile revealed that the virus has partially adapted to propagate between mammals. However, the risk to public health remains low, according to U.S. health officials.
Vivien Dugan, acting director of the influenza division at the U.S. Centers for Disease Control and Prevention’s National Center for Immunization and Respiratory Diseases, told the New York Times: “These genetic changes have been observed in past H5N1 infections, but they have not resulted in human-to-human transmission.”
Dugan added, “However, it is essential to continue examining every instance of human infection, as well as other mammalian spillover events, and to monitor viral evolution in birds.” “We must remain vigilant for mutations that would render these viruses more dangerous to humans.”
According to the CDC, while the two mutations found in the PB2 gene can help the virus replicate in mammals, the samples lacked other genetic alterations that would enable the virus to stabilize and bind securely to human cells.
Richard Webby, a bird flu expert at St. Jude Children’s Research Hospital, told the Times, “There are three major categories of changes that we believe H5 must undergo to transform from a bird virus to a human virus.” “The sequences from the individual in Chile belong to one of these classes of mutations. But we also know that this is the simplest of these three sets of changes for the virus to make.”
No additional cases have been attributed to the man infected with the H5N1 virus. His symptoms began with a cough and congested throat, according to the World Health Organization, which received a report of the man’s illness from Chile’s Ministry of Health on March 29. It is unknown how the 53-year-old male became infected, but there have been cases in birds and sea lions in his region.
WHO officials stated, “According to the preliminary findings of the local epidemiological investigation, the most plausible hypothesis regarding transmission is that it occurred through environmental exposure to areas where sick or dead birds or marine mammals were found close to the case’s residence.” The patient is still hospitalized. Health officials believe the mutations occurred as the infection spread throughout the patient’s body.
An influenza virologist from Emory University in Atlanta, Anice Lowen, explained to the Times that the mutations represent a step on the path to adaptation to humans and increased risk to humans. Consequently, it is unsettling to see them. The Chilean case is the eleventh human case reported by the CDC since January 2022.
The virus has occasionally spread among mammals, including at a mink farm in Spain last autumn, and “continued sporadic human infections are anticipated,” according to the CDC. The new mutations are a “step in the wrong direction,” according to Lowen.