BEIJING, Feb. 10 (Xinhuanet) -- Chinese health official said Friday that some cases of human infection of bird flu were caused by environmental pollution.

    The human cases found in the areas where no outbreak of bird flu in animals had been reported were caused by environmental pollution by sick or dead birds, said Mao Qun'an, spokesman for the Ministry of Health, at a press conference.

    About one third of the reported human case of bird flu in the world were found in areas with no outbreak in animals, said Mao, adding the exact channels of the human infection are under investigation.

    Asked the reason of higher mortality rate of bird flu cases in China, Mao said some grassroots health departments are weak in early finding and timely treatment of patients. "And the disease often come on fast and results in crock-up of multiple organs, which also result in high mortality," Mao told the press conference.

    According to the official, the ministry has strengthened support to grassroots medical staff in terms of financial assistance and training, and also warned the public to stay away from sick or dead poultry.

    "People with suspected symptoms should go to hospital as soon as possible," he said.

    China has reported 11 human cases of bird flu since last October, among whom seven have died. The mortality rate is 63.6 percent.

    A total of 166 cases involving 88 deaths have been reported to the World Health Organization (WHO) by Feb. 9 with the mortality rate of 53 percent, according to the WHO website. Enditem