Scientists discover mutations in bird flu but assess risk to be low

According to U.S. health officials, a man in Chile has been infected with a bird flu that has mutations that could cause the virus to be more harmful or spread more easily. However, they also said that there is no evidence that the mutations would make it easier for the virus to take root in a person’s upper lungs, which would be a cause for concern about spread among people. The mutations do not 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 have only appeared in the one hospitalized patient, may have occurred after the man became sick. There is no evidence that the mutated virus spread to other people, mixed with other flu viruses, or developed the ability to fight off current medicines or evade vaccines. Genetic changes such as these have been seen in past bird flu infections. Nevertheless, Dugan said that it is important to continue to look carefully at every instance of human infection and remain vigilant for changes that would make these viruses more dangerous to people.

Since the first identification of Type A H5N1 in 1997, which was a threat to people during an outbreak in Hong Kong when visitors to live poultry markets caught it, sporadic outbreaks have followed, and more than 450 people have died from bird flu infections in the past two decades, according to the World Health Organization. The vast majority of infected people got it directly from birds.

As bird flu hits other species, scientists fear the virus could evolve to spread more easily among people. The virus has been spreading widely, to birds and animals in scores of countries. In the U.S., it has recently been detected in wild birds in every state, as well as in commercial poultry operations and backyard flocks across the country. Since the beginning of last year, tens of millions of chickens have died of the virus or been killed to stop outbreaks from spreading, one of the reasons cited for soaring U.S. egg prices.

The new lab analysis looked at the virus found in the lungs of a 53-year-old man living in Chile’s Antofagasta region. It may be that he became infected through contact with sick or dead birds or infected sea lions, according to a WHO summary of the case. The man was healthy and had not travelled recently. On March 13, he started getting a cough, sore throat and hoarseness, the WHO said. His symptoms worsened, and he eventually was sent to an intensive care unit and treated with antiviral medicines and antibiotics. He is still hospitalized and being monitored, CDC officials said.

Andrew Pekosz, a flu researcher at Johns Hopkins University, said he hasn’t seen the preliminary analysis of the Chilean patient’s infection. “When these viruses get into humans, there’s a likelihood that they start to adapt to grow better in us,” and this is a sign that is happening, he said. There are three or four kinds of mutations that would need to be seen in an H5N1 virus “before that would really raise the alarm signal that something is happening of concern,” he added.