- The Washington Times - Monday, June 16, 2003

BEIJING ? After four months of frantic but largely successful efforts to contain SARS in China, World Health Organization (WHO) experts are now focusing on finding the source of the illness and preventing a new outbreak.

The number of new SARS cases in China, the worst-hit country in the world, has dwindled to just a handful in June, leading to a widespread belief that control measures are working and that the mysterious pneumonialike disease may be on the brink of disappearing — for now.

“Before we can talk of eradication we need to know all the facts,” said Peet Tull, a Swedish epidemiologist who has been in Beijing monitoring the disease for the last five weeks.

“I think it is about eradicated, but there are some problems. One is the environment. How did it get started? We have to find the source,” he said. “Another question is the subclinical carrier, people who don’t have the disease but carry the virus. This is a concern but so far from the epidemiological cycle there is no data supporting this.”

Finding the source of the disease will help to know whether SARS can truly be eradicated, or whether it could become an endemic, a regularly recurring disease like hepatitis, tuberculosis or a number of other common illnesses.

“Being an endemic disease is partly related to whether there is a reservoir [of the virus] in animal sources, and partly related to whether the control measures can be maintained,” said Daniel Chin, a Beijing-based WHO medical officer.

“In other words, it may keep coming back, but if you have adequate control measures you can keep containing it,” he said.

Whether SARS will become an endemic disease has been at the root of the international fuss over the epidemic that has infected some 8,400 people and killed more than 780 worldwide since it was first discovered in southern China in November.

SARS has not been as fatal or infectious as many other diseases but its recent appearance and unanswered questions about its spread and origins have set alarm bells ringing.

By March, researchers worldwide had identified a new strain of the coronavirus, long known for causing the common cold, as the cause of SARS.

In late May, Chinese and Hong Kong researchers found strains of a coronavirus in a number of wild animal species being bred for southern China’s exotic food restaurants that were more than 99.8 percent similar to the SARS coronavirus found in humans and the likely origin of SARS.

They also found that some wild animal breeders and sellers were carrying SARS antibodies without ever coming down with the disease, meaning that SARS might have spread through these “subclinical carriers” to others, Mr. Tull said.

“The WHO hopes to send a team down to Guangdong to look into these studies. A lot more work needs to be done here,” he said, in order to verify that these animals were the source of the outbreak.

Another puzzle for WHO officials is that up to 50 percent of the cases in Beijing and as many as 20 percent in nine other Chinese provinces and cities cannot be traced to a known SARS source. These patients have no history of contact with other SARS patients.

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