SARS Epidemic Is Largely Over, Experts Say
Except in China and Taiwan, Measures Apparently Stemmed Virus's Spread
By Rob Stein
Washington Post Staff Writers
Sunday, May 18, 2003; Page A13
The SARS epidemic appears to be coming to an end everywhere there has been an outbreak except China and Taiwan, scientists concluded at the close of an international assessment yesterday.
Aggressive measures to identify and isolate victims early have brought outbreaks under control in Hanoi, Toronto, Singapore and Hong Kong, experts announced at the end of a 11/2-day World Health Organization meeting.
WHO brought together more than 40 leading epidemiologists from 16 countries to assess the state of the epidemic and what is known about the new lung disease, which has struck at least 7,761 people and killed at least 623 in 28 nations.
"I think the message coming out of this meeting is certainly one of great hope, it's one of celebration that the measures are working, but also a call to action because we've got a lot more to do yet before we end this problem," said Michael J. Ryan, coordinator of WHO's Global Alert and Response program at a briefing at the conclusion of the meeting.
The researchers agreed that most of WHO's previous conclusions about severe acute respiratory syndrome held true, including the fact that it has a 10-day incubation period and an overall mortality rate of 14 percent to 15 percent.
Outbreaks of the disease have followed a strikingly similar pattern around the world, noted Margaret Chan, director of Hong Kong's health department.
The primary mode of transmission is through droplets expelled when victims cough or sneeze, although the disease may spread in some instances through feces, the scientists said.
The chain of transmission can be broken by identifying patients quickly, isolating them and tracking down all their close contacts to make sure none infects anyone else, the experts said.
Although the epidemic is much larger in China than elsewhere, the same approach should be able to work there as well, and Chinese authorities appear to be rapidly improving their implementation of those measures, the scientists said.
"The experience across the range of countries involved has been that the control measures that we have designed have managed to break the cycle of transmission through the simple implementation of case finding, contact tracing and isolation practices in hospitals," Ryan said. "This has been the key factor, and we've seen the number of secondary cases per case dropping systematically in all the countries to a point now where we believe, in the majority of cases, we are now seeing the epidemics coming to an end."
Although China still faces "a difficult situation" because of the sheer size of the nation, "it's not any more complex than it is in the rest of the world," Ryan said.
"We need to assist our Chinese colleagues in implementing the same measures in a very aggressive manner," he said.
Several researchers meeting yesterday at the New York Academy of Sciences said it appears likely the coronavirus that causes SARS in humans likely originated in an animal in southern China.
"I think it jumped from an animal, but we don't know which one," said Kathryn Holmes, a molecular biologist at the University of Colorado Health Sciences Center who has studied coronaviruses extensively. She expressed optimism that the carrier animal can be found in Guangdong province where the first SARS cases occurred last November. "They'll bleed every critter in that region" and test the blood for the virus, she said.
Holmes said there are numerous ways the virus could have leaped from the animal population to humans, including handling or eating the animal or contamination from fecal waste.
Linda Saif, a researcher at Ohio State University's Agricultural Research and Development Center, suggested Chinese scientists test wild animals since this particular coronavirus has not been seen in more common household animals such as cats, chickens or pigs.
Although scientists have not yet found the SARS virus in a particular animal, Saif said they have derived valuable clues from studying other animal coronaviruses -- some encouraging data and some more worrisome.
"Shipping fever," an illness that affects cattle when they travel from farm to feedlot, shows some parallels to SARS patients whose illness may have been exacerbated by the stress of travel, she noted. In some animals, the coronavirus reappears and reinfects, raising concerns about the future health of SARS survivors.
Perhaps most alarming, Saif said, was one recent experiment showing that pigs infected with both the coronavirus and influenza became much sicker than those infected with just the coronavirus. With the recent cases of avian influenza in people in the Netherlands, she said: "You can imagine what would happen if both these viruses infected people together."
There is no evidence that animals or insects are spreading the disease, WHO coordinator Ryan said. While it is possible that some people may develop either no symptoms or very mild symptoms, there is no evidence the disease is being spread in any significant way by such individuals, he said.
Patients appear to be most infectious in the second week of their illness, but the experts recommended that health workers treat all cases as if they were highly infectious to minimize the risk of spread.
Researchers have not identified any animals that can be infected with the virus. If none exist, then there would be nowhere for the virus to hide if it were eliminated from humans.
One of the areas in which the researchers recommended warranted additional study is whether children are vulnerable to the disease.
Staff writer Ceci Connolly in New York contributed to this report.
© 2003 The Washington Post Company
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