SARS may return

KUALA LUMPUR—SARS may come back, even if for now it seems to be under control, Hong Kong's Health Minister Margaret Chang told The Scientist on the closing day of the World Health Organization global conference on severe acute respiratory syndrome (SARS) in Kuala Lumpur (June 17–18).Gro Harlem Brundtland, the outgoing WHO director general, spoke only of beating this "round" of SARS, and Chang said, "It's hard to say how it will come back… A lot more work is needed to establish the origin of the virus." In a guarded appeal to China to assist this research, she added, "We urge the WHO, working with the countries with the greatest disease burden, to study this."But David Heymann, director of Communicable Diseases at WHO, had a different emphasis. He said that the conference had talked about "eradication." For this, stopping transmission among people was only the first step. "The next step is to find and control [the source] so the disease never enters the population again."Mike Ryan, who heads WHO's Global Outbreak Alert and Response Network, told The Scientist today that "there is no question that we've nearly broken the human chain of transmission." According to Ryan, "There's a bit more to do to stop current transmission in Beijing, and in Hong Kong and Canada—but if we keep doing what we've been doing, we'll eliminate this as a public health problem. The question is, will it be reintroduced into the population?"The conference had heard from Thomas Tsang—who led the investigation into the outbreak at Amoy Gardens in Hong Kong, where 300 people contracted SARS in one group of apartment buildings—that 10% of asymptomatic people there carried the SARS virus. But according to Ryan, such carriers are not the threat. "All the studies show that within 10 to 20 days, such people are clearing the virus from their systems."For reintroduction of the disease, "The most likely scenario is an animal source, [as happens in] Lassa fever and Ebola," said Ryan. The observation of the virus, or a closely related form, in palm-faced civet cats and a raccoon dog, does not constitute identification of the source, according to Ryan. "We don't understand the natural ecology of this disease, the range of the animal and the dynamics of the population," he said. "And the virus changes—there's a lot to be understood about that." Once the animal source was better understood, surveillance systems would have to be put in place as close as possible to the ecological niche, said Ryan.If this was the public health perspective on SARS research, the conference also heard that basic research was needed on almost everything to do with SARS, from epidemiology to vaccine development. There seemed to be consensus that "standardization" and full evaluation of diagnostic tests was the most urgent task, especially to distinguish SARS cases from those of "winter flu" in the coming season. Standardized diagnostics also underpin other research on SARS, the conference heard, as they would be needed for studies of epidemiology, virus excretion, antibody kinetics, and for environmental studies.For standardization, WHO's Klaus Stöhr argued strongly for a "well pedigreed panel of specimens," to validate tests coming onto the market, including a panel of virus isolates, geographically and temporally diverse, with clinical data and antigenic characterization. A panel of reagents was also needed, said Stöhr. WHO may coordinate these panels. Laboratory capacity in Asia would also need to be developed.There is also a need for better protocols for testing and investigation of antivirals, Ryan said. "We shouldn't be scrambling around trying to find out what drug we can use. We've got broad-spectrum antivirals like ribavirin. We should have protocols already approved in advance for viral outbreaks like SARS, or at least partly made up ready for approval in an emergency. We have to be a lot quicker off the mark next time."The biological weapons agenda has generated a huge investment in antivirals, Ryan claimed, and WHO should be able to tap these products in an emergency. Brundtland, questioned on this by The Scientist, said, "I certainly think that the military sector is aware of health as a global security problem. There is a lot of investment in that area. They should put some of that into a broader public health agenda, and viruses would be one focus. One on the big problems is that we haven't in any sizeable way found medication against viruses."A new disease has been identified every year for the past 20 years, Brundtland said, and "The capacity to react quickly to these outbreaks is so important."

SARS may return

Global conference sets agenda for research to control future outbreaks

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