Bird flu virus in humans mutating

The H5N1 strain of bird flu seen in human cases in China has mutated "to a certain degree", as compared with strains found in human cases in Vietnam, state media reported, citing Chinese Ministry of Health spokesman Mao Qun'an. "But the mutation cannot cause human-to-human transmission of the avian flu," Mao said. Meanwhile, Shanghai began screening international passengers for fever and other bird flu symptoms, The Wall Street Journal reported. China this month confirmed its first three human cases of bird flu, two of which were fatal.