Cientistas Noruegueses detectam mutação no vírus H1N1
Scientists in Norway announced Friday they had detected a mutated form of the swine flu virus in two patients who died of the flu and a third who was severely ill, the most recent report of mutations in the virus that are being watched closely for any change that could make it more dangerous.
Norwegian scientists detect mutated form of swine flu
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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.
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.
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.
A top U.S. health official said the mutation was no reason for alarm.
"I don't think that it yet has the public health implications that we worry about," said Anne Schuchat, director of the federal Centers for Disease Control and Prevention's Center for Immunization and Respiratory Diseases. Schuchat noted that some patients have gotten severely ill, including developing pneumonia, after being infected with strains of the virus without the mutation.
The World Health Organization said viruses with a similar mutation had been detected in several other countries, including Brazil, China, Japan, Mexico, Ukraine and the United States. "No links between the small number of patients infected with the mutated virus have been found and the mutation does not appear to spread," the WHO said in a statement.
The Norwegian 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.
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.
"It is, at the moment, reassuring that this appears not to be spreading," said William Schaffner, of Vanderbilt University. He said mutations that make episodes of swine flu more severe are most dangerous only if they are "easily transmissible." "That's a different characteristic," Schaffner said. "And apparently that does not appear to have happened to this virus. It does not seem to be spreading in the general population."
Detection of the mutation should be reassuring, Schaffner said, because it illustrates the intensity of the global effort to monitor the virus. "The virologists are keeping an eye on H1N1 and this is evidence of that," Schaffner said. "We should be pleased the virologists are doing such a good job of tracking this flu virus."
The CDC, meanwhile, is investigating a cluster of four cases of patients at the Duke University Medical Center in Durham, N.C., who were found to be infected with H1N1 virus that was resistant to the antiviral drug Tamiflu. All four patients were treated with another antiviral drug, known as Relenza.
The news of virus mutations came as the level of flu activity in the United States appeared to be declining. The number of states reporting widespread flu activity dropped from 46 to 43 in the past week, and had dropped in all 10 regions across the country, the CDC said.
But Schuchat said flu cases were still rising in some states and it was too soon to know whether activity would surge again. Officials were especially worried about the upcoming Thanksgiving holiday, when many people would be traveling and families will be gathering, increasing the chances of the virus spreading.
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