"Researchers have identified some of the changes that a flu virus needs to become a deadly pandemic strain, and they said the H5N1 avian influenza virus has so far made only a few of them.
"The study may help scientists watch for the mutations most likely to make H5N1 a global threat.
"David Finkelstein of St. Jude Children's Research Hospital in Memphis and colleagues looked at H5N1 virus samples from people who had been infected. They found none were anywhere near as mutated as flu viruses that caused the three most recent pandemics, notably the 1918 Spanish flu that killed tens of millions worldwide.
"Writing in the Journal of Virology, Finkelstein's team said they identified 32 clear-cut changes in influenza viruses that differentiated a human flu from a bird flu.
"Even when H5N1 viruses infected people, each one had made one or two of these changes at the most, Finkelstein said.
"'We think they need to get to 13 to be truly dangerous,' Finkelstein said in a telephone interview."Comment: This seems to be quite good news. The H5N1 has been considered to be a likely agent for a new flu pandemic, and its lethality in those infected to date has resulted in fears that if it did cause a pandemic, that pandemic would cause a very large number of deaths. The new finding seems to suggest that an H5N1 pandemic may not be as imminent as was feared. Moreover, if a large number of genetic changes are required to make the virus capable of causing a major epidemic, one might hope that the lethality will decrease as a result of those changes. JAD
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