Beijing – Two and a half years after a mysterious respiratory illness from southern China infected thousands of people around the world and brought dire predictions of a recurring and deadly plague, the virus known as SARS has again provided a surprise.
It has disappeared, at least for the moment.
Not a single case of severe acute respiratory syndrome has been reported this year or in late 2004. It is the first winter without a case since the initial outbreak in late 2002.
In addition, the epidemic strain of SARS that caused at least 774 deaths worldwide by June 2003 has not been seen outside a laboratory since then.
SARS is not even the nastiest bug in its neighborhood, as health officials warn that avian influenza in Southeast Asia poses a far greater threat.
In cities like Guangzhou and Beijing, once under a state of alert because of SARS, public hysteria about the disease has long since given way to public nonchalance.
“Very few people talk about it anymore,” said Cheng De, 22, as he walked through a subway tunnel last month in Guangzhou, the city at the center of the first two SARS outbreaks.
“People think it is in the past.”
Health officials in China also are less alarmed, but they warn that SARS could still pose a threat. This caution is partly because so much about the virus is still not fully known: What caused it to become so virulent in the initial outbreak? Where has it gone? Will it come back?
Most researchers and health officials are not counting on the rosiest scenario – that SARS has simply mutated into oblivion.
“We’d be lucky to believe that, and that would be very nice, but there is no research to support that,” said Dr. Julie Hall, the SARS team leader at the Beijing office of the World Health Organization.
“Just because we’ve not seen SARS anymore this year doesn’t mean it is not out in the wild this year,” Hall said.
This year, Dr. Kathryn V. Holmes, a prominent microbiologist who has studied corona viruses like SARS for more than 20 years, caused an immediate stir in China after giving a speech at the annual meeting of the American Association for the Advancement of Science.
News media reports in China quoted Holmes as saying that SARS no longer existed in the wild and that the virus no longer presented a serious health threat to the world.
In a telephone interview recently, Holmes, a professor at the University of Colorado Health Sciences Center in Denver, said her comments should never have been interpreted to mean that SARS no longer existed in nature. Instead, she said, she was referring to recent research showing that the epidemic strain of SARS that passed from person to person during the initial worldwide outbreak had not been seen since June 2003. That strain mutated after passing from animals to humans in a way that caused it to spread rapidly and become more virulent.
“People are trying to understand which of those mutations was responsible for human- to-human transmission and high virulence in humans,” Holmes said of one of the fundamental unanswered questions about SARS.
Holmes credited the fact that SARS had “vanished” this year to the aggressive containment efforts by the World Health Organization and the Chinese government.
“The vanishing was a piece of outstanding coordination throughout the world,” she said.
“They controlled the epidemic without having a good diagnostic test for the virus.”
Research on different SARS vaccines is underway at several laboratories in China and elsewhere. Hall, the WHO expert in Beijing, said the most reassuring discovery about SARS was that it could be contained.
But, she noted, the fact that the disease spread quickly throughout the world also shows the potential for more serious diseases like avian flu to cause an epidemic.
“One thing that has come out of SARS is the need to strengthen public-health surveillance,” Hall said. “If SARS revealed the gaps in the system, then avian influenza has increased the urgency to fill those gaps.”