Scientists discover mutations and say the threat is still low

A man in Chile is infected with bird flu that has worrying mutations, but the threat the virus poses to people remains low, U.S. health officials said Friday.

Previous animal studies suggest these mutations could make the virus more harmful or spread more easily, health officials said. But they also said there was no evidence the mutations would make it easier for it to take root in a person’s upper lungs – a development that would raise concerns about it spreading among people.

The mutations don’t change public health officials’ assessment of the overall risk to people from the H5N1 virus, which “continues to be low,” said Vivien Dugan of the Centers for Disease Control and Prevention.

The mutations, which only appeared in a single hospital patient, may have occurred after the man fell ill, CDC officials said. There is no evidence that the mutated virus has spread to other people, mixed with other flu viruses, or developed the ability to fight current drugs or evade vaccines. agency officials said.

Such genetic changes have been observed in past bird flu infections.

“Nevertheless, it is important to continue to carefully review each case of human infection,” Dugan said. “We need to stay alert to changes that would make these viruses more dangerous for people.”

Threat first identified in 1997

This type of flu, called Type A H5N1, was first identified as a threat to people during a 1997 outbreak in Hong Kong, when visitors to live poultry markets caught it.

Sporadic outbreaks have followed and more than 450 people have died over the past two decades from bird flu infections, according to the World Health Organization. Most infected people got it directly from birds.

However, as bird flu strikes other species, scientists fear the virus will evolve to spread more easily among humans. And it has spread widely to birds and animals in dozens of countries.

Millions of dead chickens

In the United States, it has recently been detected in wild birds in all states, as well as commercial poultry farms and backyard flocks. Since the start of last year, tens of millions of chickens have died from the virus or been killed to prevent the spread of outbreaks, one of the reasons cited for soaring egg prices in the United States.

The new lab analysis focused on the virus found in the lungs of a 53-year-old man living in Chile’s Antofagasta region. He may have been infected through contact with sick or dead birds or infected sea lions, according to a WHO summary of the case.

The man was in good health and had not traveled recently. On March 13, he started having a cough, sore throat and hoarseness, the WHO said.

His symptoms worsened and he was eventually sent to an intensive care unit and treated with antiviral drugs and antibiotics. He remains hospitalized and monitored, CDC officials said.

Genetic sequencing this week revealed the two concerning mutations. Chilean and US health authorities worked together on the investigation.

Andrew Pekosz, a flu researcher at Johns Hopkins University, said he had not seen preliminary analysis of the Chilean patient’s infection.

“When these viruses get into humans, they’re likely to start adapting to grow better in us,” and that’s a sign that’s happening, he said.

There are three or four types of mutations that would need to be seen in an H5N1 virus “before it really raises the alarm bells that something of concern is happening,” he added.