Authorities in southwest China are investigating a mysterious disease that has killed 17 farm workers and left 41 others ill after they handled sick or dead livestock, state media said on Monday.

The government of Sichuan province has dismissed speculation that the deaths were caused by bird flu or severe acute respiratory syndrome (SARS), an assessment affirmed by the World Health Organization.

“From the information we have it doesn’t seem to be related to bird flu. We made that distinction based on the symptoms described to us by the government,” said Bob Dietz, a WHO spokesman in Manila.

“This (disease) doesn’t seem to have a large pneumonia content or a large respiratory problem,” Dietz said.

The deaths were probably caused by a bacteria that spreads among pigs, the state-run China Daily quoted Zeng Huajin, a senior official with the Sichuan provincial health department, as saying.

“Streptococcus suis (a pig pathogen) would fit the symptoms described to us, but we will wait for an analysis from the Ministry of Health,” Dietz said.

SARS emerged in south China in 2002 and spread across 30 countries, infecting nearly 8,500 people and killing about 800.

It re-appeared in China last year but there were only a few isolated cases. The Chinese government was accused of initially covering up the disease.

Global health officials also have been on high alert over a bird flu virus that has killed over 50 people in Asia since late 2003.

Initially, 20 farm workers suffered fever, nausea and haemorrhaging after handling sick or dead pigs and sheep in 12 towns and 15 villages in Jianyang city and Ziyang city’s Yanjiang district, the China Daily said.

But more cases were reported as health workers combed villages, the newspaper said. By noon on Saturday, 58 people suspected of contracting the strange disease had been reported in Ziyang and neighboring Neijiang.

The victims were sent to local hospitals, where two had recovered, 12 were in critical condition and 27 were stable, the official Xinhua news agency said.

The Ministry of Health and provincial officials were not immediately available for comment. Staff at Ziyang No. 1 People’s Hospital declined to comment.

Dietz said Chinese authorities had reacted well to the mysterious outbreak.

“Any time you see a number of deaths like this, it’s reason for concern, and it bears close looking at. Having said that, we’re very comfortable with the way China has responded to this, they’ve pretty much done a textbook response,” he said.

“Medical experts said the mysterious disease doesn’t seem to be spreading further among humans and the detected cases show no obvious signs of epidemic,” Xinhua said.

Hong Kong has ordered hospitals to be on alert for people exhibiting systems such as fever, malaise, nausea and vomiting.

It has also advised travelers to Sichuan to take precautions such as not touching dead animals, using mosquito repellant and reporting any illnesses to doctors.

Newspapers reported the city’s two major supermarket chains, Parknshop and Wellcome, had suspended sales of frozen pork from Sichuan. But government officials said they were not banning such products, saying the risk of the disease spreading to Hong Kong was low.