A 29-year old man has been diagnosed with bird flu and is in critical condition in southwest China, health authorities said Sunday. Bird flu has killed four people in China this month. For instance, a woman in China's far west died Friday from bird flu, the fourth death this month, just as millions of people are on the move to return home for the traditional Lunar New Year. Moreover a teenage boy died on Tuesday in the central province of Hunan.

The man, surnamed Zhou, fell ill on January 15 in the southwestern province of Guizhou, the official Xinhua news agency reported, quoting local health authorities. He tested positive for the deadly H5N1 strain of the virus on Sunday, and was still in a critical condition, the report said.

The other three deaths appear not to be related, the wire service reports, coming in three different geographic regions. In all, 22 people in China have died from this strain of flu since 2003, the A.P. reports. As in all other human cases reported by WHO, this incident of bird flu appeared to be contracted by contact with poultry or fowl and not transmitted from human to human.

Provincial health and agriculture departments must report to the Health Ministry, Agriculture Ministry and the State Administration for Industry and Commerce every day on whether there have been infections in their areas. The Agriculture Ministry has also ordered increased monitoring and management of live poultry markets.

Despite the new cases, the Ministry of Health has said there is no evidence of a large-scale outbreak of bird flu. It said the illnesses were isolated, unrelated and did not show significant mutations of the H5N1 virus.