All three recent SARS (severe acute respiratory syndrome) related cases in Guangzhou -- including one confirmed patient and two suspected cases -- are believed to have been infected with the potentially deadly virus by animals, World Health Organization (WHO) experts say.

A joint-team of experts on a mission to track down the deadly virus source believed it has traced the cause of the infection in the first confirmed SARS case even as the other two suspected cases cropped up.

The research team consists of members of the WHO, the Chinese Ministry of Health, China Center of Disease Control and Prevention (CDC), and the Guangdong CDC. The South China University of Agriculture is also on board.

"We have good reason to believe that animals are the reservoir of the ultimate source of SARS," Dr Robert Breiman, an epidemiologist with WHO and the United States CDC, said on Friday. Breiman is the team leader.

The WHO team will head for Beijing on Saturday after spending a week on its investigation in Guangzhou.

The SARS coronavirus has been detected in animal-holding cages in the restaurant in which the suspected SARS patient -- a 20-year-old female -- had worked, Breiman said.

It was also found in the two wild animals trading markets in the nearby area. And the female patient served dishes made from civets and other animals, Breiman said.

The virus separated from the confirmed SARS patient was nearly identical with that from civet samples, according to Guangdong CDC. Civets are a species of wild cats caught and served at area restaurants as a delicacy.

Amazingly, the restaurant owner, who has cooked wild animals like the civet for decades, was quarantined for observation but never showed signs of SARS.

Up to now, there is no record of the third patient having contacts with wild animals.

However, scientists deduce that animals are the most possible source of the disease.

"By and large, most of the diseases that have appeared in the past 10 years have, in the end, turned out to be from an animal source,'' Breiman said.

"Understanding the potential of animal reservoirs for disease is an important part in any investigation for the new diseases,'' he added.

The SARS that has infected the known patients this year has seemed a less virulent form than last year, the researcher said, infecting people who come into contact with animals, but not always.

"Very possibly, it's a variation virus that isn't transmittable from person to person," he said.

All the 100 people who had contact with the second suspected patient -- including 48 having close contact -- have shown no symptoms.

About 30 people who had contact with the third patient, including 14 with close contact, have developed no symptoms. Some are still under medical observation.

The two suspected patients are well enough to be discharged from hospital soon, even though no final conclusion on whether they had SARS to a high-degree of medical certainty has been made, said Tang Xiaoping, chief of the Guangzhou Municipal No 8 People's Hospital, where the patients were hospitalized.

Wang Zhiqiong, deputy director of the Health Bureau of Guangdong Province, said Guangzhou will host an international seminar on SARS soon.

(China Daily January 17, 2004)