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BEIJING, Jan 25 (Reuters) - A man in the southwestern Chinese province of Guizhou has been infected with bird flu and is in a critical condition in hospital, the Health Ministry said on Sunday.

It is the sixth human case of bird flu to be reported in China this year. The Chinese Health Ministry said on its website (www.moh.gov.cn) the latest victim was a 29-year-old man surnamed Zhou who fell sick on Jan. 15.

In recent weeks four people have died of bird flu in China.

"Epidemiological tests show that the patient previously had exposure to live poultry markets," the ministry said in a brief statement.

But nobody with whom he had been in close contact had shown signs of illness, it added.

Even before the latest case, Chinese health officials had been urging extra vigilance this month, when the winter weather was suspected of having helped the virus spread.

Other recent victims fell ill in areas where there had been no known outbreaks of H5N1 in birds.

The H5N1 strain remains largely a virus among birds. Experts say there is a danger that it may evolve into a form that can be transmitted among humans, risking a pandemic in which millions could die.

Including the latest case, at least 36 people have been infected in China and 24 have died from H5N1 to date. (Reporting by Ben Blanchard; Editing by Alex Richardson)

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