Bird flu in Chilean man shows virus adapting to human spread

By Cara Murez HealthDay Reporter

MONDAY, April 17, 2023 (HealthDay News) — Tests on a Chilean man infected with bird flu showed signs that the virus has partially adapted to spread between mammals. However, the risk to public health still remains low, according to US health officials.

“These genetic changes have already been observed with past H5N1 infections and have not resulted in spread between people,” vivian duganacting director of the influenza division at the National Center for Immunization and Respiratory Diseases at the U.S. Centers for Disease Control and Prevention, told the New York Times.

“Nevertheless, it is important to continue to carefully review each case of human infection, as well as other mammalian spread events, and to monitor viral evolution in birds,” Dugan added. “We need to stay alert to changes that would make these viruses more dangerous for people.”

While the two mutations seen in the PB2 gene may help the virus replicate in mammals, the samples lacked other genetic changes that would allow the virus to stabilize and bind tightly to human cells, the CDC says. .

“There are three broad categories of changes that we believe H5 must undergo to transition from an avian virus to a human virus,” Richard Webbyan avian flu expert at St. Jude Children’s Research Hospital, told the Time. “The footage from the person in Chile has one of those categories of changes. But we also know that of these three sets of changes, this is the easiest for the virus to make. »

No other cases have been linked to the man infected with the virus known as H5N1. His case began with a cough and sore throat, according to the World Health Organizationwho received a report of the man’s illness on March 29 from the Chilean Ministry of Health.

Although it is unclear how the 53-year-old man became infected, there have been cases in birds and sea lions in the area where he lives.

“According to the preliminary results of the local epidemiological investigation, the most plausible hypothesis regarding transmission is that it occurred by environmental exposure to areas where sick or dead birds or marine mammals were found nearby. of the residence of the case,” WHO officials said. .

The man remains hospitalized. Public health officials believe the mutations occurred when the infection spread through his body.

“We understand them [the mutations] be a step on the road to adaptation to humans and increased risk to humans,” low anisea flu virologist at Emory University in Atlanta, told the Time. “So, certainly, it’s disturbing to see them.”

The virus has occasionally spread among mammals, including at a Spanish mink farm last fall and “continued sporadic human infections are expected,” the CDC said.

The new mutations are a “step in the wrong direction,” Lowen said.

The US Department of Agriculture has more on H5N1.

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