http://www.msnbc.msn.com/id/11927943/
Study finds two separate bird flu strains
Genetic changes in virus could complicate prevention of pandemic
Interior Secretary Gale Norton told reporters Monday that it was “increasingly likely” that bird flu could be detected in the United States this year.
Updated: 5:01 p.m. ET March 20, 2006
ATLANTA - The H5N1 strain of bird flu in humans has evolved into two separate strains, U.S. researchers reported on Monday, which could complicate developing a vaccine and preventing a pandemic.
One strain, or clade, made people sick in Vietnam, Cambodia and Thailand in 2003 and 2004 and a second, a cousin of the first, caused the disease in people in Indonesia in 2004.
Two clades may share the same ancestor but are distinct — as are different clades, or strains, of the AIDS virus, the team from the U.S. Centers for Disease Control and Prevention found.
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