In Hong Kong, a government source said more than 60 percent of the city's pigs carried the streptococcus suis bacteria, but their meat was fit for consumption as long as they showed no symptoms of the disease.

The mortality rate of almost 25 percent has caused concern for the World Health Organization, which pledged to monitor the situation closely.

In Sichuan, Yang Weizhong, a Ministry of Health expert sent to the infected area, stressed there was no evidence that the bacteria, streptococcus suis type II, could infect human beings through the digestive system. He said the victims had all butchered or processed infected pigs.

Meat Fit for Consumption

Streptococcus suis type II is a relatively widespread pig-borne bacteria but human infections are rare. Prior to the current outbreak, only 200 cases had been recorded globally.

By noon yesterday, there were five laboratory-confirmed cases, 71 clinically confirmed cases and 41 suspected cases. Among the cases, only five people have been cured and discharged from hospital.

Bob Dietz, a WHO spokesman in Manila, said that based on Sunday's figures, the high death rate was a concern. "It is a situation which bears close watching," he said.

In Hong Kong, a government source said more than 60 percent of the city's pigs carried the streptococcus suis bacteria, but their meat was fit for consumption as long as they showed no symptoms of the disease.

First Report of Large Outbreak

Secretary for Health, Welfare and Food York Chow Yat-ngok yesterday reiterated that there was no need to ban imports of frozen pork from Sichuan.

"We have proved that neither pigs nor staff from the pig farms in Sichuan that supply us with frozen pork were sick," he said.

Hong Kong University associate professor of microbiology Ho Pak-leung expressed concern over the virulence of streptococcus suis in Sichuan.

"It is unusual because this infection has never been reported in the literature to cause large outbreaks in humans," he said.

Lu Chengping, a veterinarian professor at Nanjing Agricultural University, also said the high number of human infections was unusual, but added it was easier for Chinese farmers to contract the disease as pigs were raised in small holdings rather than in large farms, as in western countries.

According to the Sichuan Animal Husbandry and Food Bureau, the infected pigs were found in three counties in Ziyang city and one county in Neijiang city . It said the 469 pigs killed by the disease were scattered across about 300 small farms.