News Release

Can we halt the deadly SARS?

Reports and Proceedings

New Scientist

AS CONCERN grows over the continuing spread of severe acute respiratory syndrome, or SARS, the key question is whether the disease can be contained. The answer will depend on how the virus spreads and evolves, which is still uncertain, and on whether healthcare systems, particularly in developing countries, can spot SARS and respond effectively.

So far, more than 1900 people in 22 countries have contracted SARS, of whom 63 have died. While China, Hong Kong and Singapore are hardest hit, some experts fear that poor public health monitoring in some countries may mean the number of cases is actually much higher.

The World Health Organization is bracing itself for outbreaks in countries currently claiming to be unaffected by SARS, including Cambodia, Indonesia and the Philippines. "We genuinely believe they have no cases at the moment. But we take the possibility of new outbreaks in this region very seriously," says Peter Cordingley, a spokesman for the WHO's Western Pacific headquarters in Manila.

The disease has so far been detected mainly in countries with good healthcare systems. But David Heymann, head of infectious diseases at the WHO in Geneva, says infected people may well have travelled to a country where an unexplained high fever and cough will not immediately draw attention. But the fact that SARS often infects healthcare workers could give it away, he says.

Even where healthcare facilities are good, it is extremely difficult to monitor an infection with such common symptoms and for which there is not yet a lab test. "With influenza, there is a well-defined test and a worldwide network set up to monitor it- and still there are nasty holes in that network," says Alan Hampson of the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne, Australia.

India could already have undiagnosed cases, he says, as it only started checking airline passengers for SARS on 31 March. "Any country where the healthcare infrastructure is not good and there are crowded living environments may be an area where SARS could establish and maintain itself- and that would be a problem for the world."

For the virus to spread seems to require some form of contact: people touching the same elevator button, for instance, which could explain the recent cluster in a Hong Kong high rise. But the crucial factor determining whether SARS can be contained may not be how it is spread but who can spread it.

If people have to be seriously ill before they can infect others, then sick people can be detected and quarantined. "Then there is a chance we could confine it to Asia, with occasional incidents elsewhere," says Albert Osterhaus of Erasmus University in Rotterdam. Airports from Toronto to Singapore are already screening would-be passengers.

But if people can harbour and transmit the virus while while remaining healthy, or showing few symptoms, it will be much harder. "If there are silent carriers, it will be virtually impossible to contain," warns Osterhaus. This issue is now the focus of research, says Heymann. A lab test for SARS would give a huge boost to surveillance and containment efforts. Many of the scientists at 11 laboratories in nine countries working on the problem think the disease is caused by a new coronavirus. But tests for the virus have yet to be validated.

Meanwhile, there is growing criticism of China. A WHO team is still waiting for permission to visit Guangdong province, where the first infections are thought to have occurred. "We only have a partial picture of what's happening in China, and the team is getting pretty irritated," Cordingley says.

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Reporting from Emma Young and Debora MacKenzie
New Scientist issue: 5 April 2003

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