A 31-year-old woman has died of bird flu in northwest China's Xinjiang Uygur Autonomous Region, becoming the fourth death from the disease in the country so far this year, the local health department said on Saturday.

The woman surnamed Zhang, a resident in the regional capital Urumqi, died at 4:40 AM on Friday, said Wang Xiaoyan, deputy director of the regional health department.

People who had close contact with Zhang have not shown symptoms of infection yet, said Wang. The official did not give the exact number of these people.

The woman in Urumqi's Toutunhe District, fell ill on January 10 after she bought live chicken in a poultry market in Changji City, which neighbors Urumqi, and ate the meat, according to Urumqi health authorities.

She first went to a private clinic and then the Changji City People's Hospital for treatment before finally going to the No. 1 Hospital affiliated with Xinjiang Medical University in Urumqi.

She was confirmed to have been infected with the H5N1 strain of avian influenza by the Chinese Center for Disease Control and Prevention on Saturday.

Xinjiang's agricultural, animal husbandry and health authorities had begun an investigation into the infection source and strengthened inspection of poultry farms to prevent possible epidemic.

Three others died of bird flu and another has been infected in the country so far this year. The first death was a 19-year-old woman in Beijing on January 5, followed by a 27-year-old woman in Shandong Province on January 17 and a 16-year-old boy in Hunan Province on January 20.

A 2-year-old girl who was critically ill with the disease was out of danger at a hospital in Shanxi Province on Friday after her vital signs remained stable for six consecutive days.

The death rate for bird flu patients is above 60 percent.

The country has warned of an even more challenging situation in preventing the disease from spreading in face of a mass migration, mostly of migrant workers and students, for the traditional Spring Festival, or Lunar New Year, which falls on January 26.

The Urumqi city government has set up a task force to prevent and control the virus. It also launched a daily epidemic surveillance and reporting system.

(Xinhua News Agency January 25, 2009)