A mystery illness that has killed 17 farmers in western China is neither bird flu nor Sars, officials have said.
The indications are that the disease is a bacterial infection spread by contact with dead pigs, and not a virus, officials in Sichuan province said.
At least 58 people showed symptoms, which include high fever, nausea and vomiting, during June and July.
The World Health Organization has urged calm, saying the disease is unable to spread from human to human.
"I can assure you that the disease is absolutely not Sars, anthrax or bird flu," Zeng Huajin, a Sichuan health official, told the China Daily newspaper.
The number of people infected with the illness has risen steadily as health officials searched through remote villages in the province for people with symptoms.
A total of 17 people have died, with just two discharged from hospital.
Twelve people remain in a critical condition while 27 are described as "stable", doctors said.
Health officials said the illness could be a variant of the streptococcus bacteria, often found in pigs.
The symptoms cannot be spread from human to human, and those most at risk from animal carcasses are people with vulnerable, low immune systems, officials said.
Experts had expressed fears that pigs, which can also carry human influenza, could accelerate mutation of the bird flu virus into a form which can be transmitted between people.
In Hong Kong, health officials warned hospitals to look out for similar symptoms, and banned the import of pork from Sichuan.
Correspondents say the territory has been wary of diseases spreading from mainland China since the outbreak of the acute respiratory disease Sars, which killed nearly 300 people there in 2003.