H5N1 may have mutated to become active in summer, health official says

H5N1 may have mutated to become active in summer, health official says

China confirmed on Thursday that the 31-year-old man in the mainland city of Shenzhen, just across the border from Hong Kong, was critically ill with H5N1.

The spread of the bird flu virus is believed to be most active in winter, when many birds migrate, according to the AP.

The official Xinhua News Agency said Thursday that the Shenzhen man, hospitalized in critical condition, had visited a local market where live poultry was sold several times before developing a fever and pneumonia on June 3.

No bird flu outbreak has been reported in Shenzhen. Health experts say close contact with infected birds puts people at high risk for infection, but the World Health Organization has said that eating well-cooked chicken does not pose a bird flu risk.