An infectious disease that has killed two dozen people in Southwestern China has sparked fears that bird flu or SARS (Severe Acute Respiratory Syndrome) has resurfaced. The World Health Organization says it is not disputing China's contention that a known pig-borne bacteria has caused the latest deaths, but says the high mortality rate is alarming.

The Chinese Ministry of Health says a bacteria (streptococcus suis) that regularly infects pigs has killed at least 24 people in Sichuan Province since last month, mainly farmers, and has infected more than 100.

Bob Dietz is a spokesman for the Western Pacific region of the World Health Organization. He says that if the numbers are accurate, the situation will mark the first time the WHO has seen such large numbers of people infected by this particular bacteria.

Mr. Dietz said it is still too early to say if a serious outbreak of the disease is imminent. "We do see a steady increase in numbers in reported cases, and a slow but steady rise of deaths. But these types of hard figures are still not reliable enough to make a prediction of course," he said.

The Ministries of Agriculture and Health say they have seen no indication that the bacteria is spreading by person-to-person contact. Mr. Dietz says the current situation, however, is still very disconcerting, because of the unusually large numbers of victims involved. "We don't understand why there are so many people getting ill. [Normally] when this disease appears, one or two, maybe three people get ill, in contact with pigs. Why all of a sudden are we seeing 117 cases of this? That is not clear to us and we don't know why that is happening," he said.

China has been hard hit by infectious diseases in the past several years. SARS, or Severe Acute Respiratory Syndrome, started in Southern China in late 2002 and spread around the world, killing almost 800 people. Bird flu, caused by a virus that can be lethal to human beings, has affected flocks of chickens and wild birds in many parts of the country.

Mr. Dietz says the WHO is monitoring the situation. Chinese authorities, meanwhile, have taken steps to keep the bacteria from spreading, including prohibiting farmers from slaughtering or processing infected pigs.