Those affected had symptoms including high fever, fatigue, nausea and vomiting, and "became comatose later with bruises under the skin", Xinhua news agency said on Sunday.
Over the past four weeks, 58 people from areas around the cities of Ziyang and Neijiang in China's southwestern Sichuan province were admitted to hospital with such symptoms, Xinhua said.
Seventeen of those in hospital have died, while 12 are in critical condition, 27 are stable and two have recovered, it said.
A "preliminary probe found out that the affected farmers have butchered sick pigs or sheep" before falling ill, the report said.
It said that medical experts believe the illness "is not spreading further among humans", and that there were "no obvious signs of [an] epidemic".
Local governments as well as health and agricultural officials have set up special teams to try to determine the cause of the illness, the report said late on Sunday night.
Pigs had been infected with
The report did not cite a suspected cause of the sickness, but authorities in Hong Kong has said earlier in the day that Chinese authorities believe a bacterial infection might be responsible for the deaths.
Zeng Huajin, a senior official with the Sichuan provincial
health department, dismissed speculation that the deaths were caused by Severe Acute Respiratory Syndrome (Sars).
Sars emerged in south China in 2002 and spread across 30
countries, infecting nearly 8500 people and killing about 800.
"I can assure you that the disease is absolutely not Sars,
anthrax or bird flu," the newspaper China Daily quoted Zeng as saying.
Zeng said the deaths were probably caused by a bacteria that
spread among pigs.
World Health Organisation spokesman Bob Dietz said the cases did not appear to be related to bird flu, a viral disease that has killed at least 57 people in Vietnam, Thailand, Cambodia and Indonesia since 2003.
The victims in Sunday's report suffered from poisoning-related shock syndrome and were acutely infected, an unidentified worker at a hospital treating the patients said in a telephone interview aired on Hong Kong's Cable TV.
"I can assure you that the disease is absolutely not Sars, anthrax or bird flu"
senior health official
The son of one of the victims told Cable TV his father fell ill after slaughtering and eating part of a sick pig.
The names of the son and victim were not given.
Pigs in the area had been infected with streptococcus bacteria, which is common in domestic animals, the hospital worker said. It was unclear if the sick sheep in the area were infected with the same bacteria.
Hong Kong's Hospital Authority has asked its hospitals to notify health authorities of any patients with the same symptoms as those seen in Ziyang, spokesman Raymond Lo said.
Hong Kong has been wary of diseases spreading from China since severe acute respiratory syndrome, or Sars, was brought to the territory by a mainlander in 2003 and killed 299 people in Hong Kong.