Mutated form of H1N1 detected in Norway

Washington Post

Scientists in Norway announced Friday they had detected a mutated form of the H1N1 flu virus in two patients who died of the flu and a third who was severely ill.

In a statement, the Norwegian Institute of Public Health said the mutation “could possibly make the virus more prone to infect deeper in the airways and thus cause more severe disease,” such as pneumonia.

Scientists have analyzed about 70 viruses from confirmed Norwegian swine-flu cases and found the mutation in only those three patients, Geir Stene-Larsen, the institute’s director general, said in the statement.

“Based on what we know so far, it seems that the mutated virus does not circulate in the population, but might be a result of spontaneous changes which have occurred in these three patients,” the statement said.

The institute has been analyzing H1N1 virus from “a number of patients as part of the surveillance of the pandemic flu virus,” and has detected several mutations, the statement said. While the existence of mutations is normal, and most “will probably have little or no importance ... one mutation has caught special interest.”

The two patients who had the mutation and died were the first swine-flu fatalities in Norway. The third patient found to have the mutated form of the virus also became severely ill.

The institute said there was no indication that the mutation would hinder the ability of the vaccine to protect people from becoming infected or impair the effectiveness of antiviral drugs in treating people who became infected.

Officials from the World Health Organization and the U.S. Centers for Disease Control and Prevention could not immediately be reached to comment.

Several flu experts said that the mutation should not cause widespread alarm. “Influenza is a mutable virus, and changes are to be expected,” said Arnold S. Monto of the University of Michigan in an e-mail. “This is typical early in the spread of a pandemic virus.”

Scientists around the world have been tracking the virus carefully for any signs that it had mutated into a more dangerous form. While a variety of mutations have been detected, most have not appeared to have affected the virus in any significant way. There have been some mutations that make the virus more resistant to antiviral drugs, experts said, but — like the mutation that may cause more severe illness — those, too, seem self-contained.