AS THE mysterious new 鈥渟uper pneumonia鈥� spreads rapidly around the world, experts on infectious disease are coming under intense pressure to identify its cause. But as 快猫短视频 went to press the pathogen underlying the disease, dubbed 鈥渟evere acute respiratory syndrome鈥�, or SARS, was still not known.
The symptoms suggest that a virus is the most likely culprit 鈥� either one behaving abnormally or one that has not caused human disease before. But for now, doctors are having to rely on guesswork to treat patients, and are prescribing antiviral drugs and antibiotics in the hope that something will work.
SARS has been diagnosed in 167 people, and has killed at least four in a growing list of countries that already includes Canada, Germany, Vietnam and China. Further cases are under investigation in Britain, the US, Australia and Israel. And some 300 people, six of whom have died, are believed to have been infected in Guangdong Province, China, where the outbreak may have started several months ago. Details of that outbreak remain murky, and the Chinese government has been criticised for being slow to call in the World Health Organization.
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Desperate to make up for lost time, infectious disease experts are now doing everything they can to track down people who may have come into contact with the disease, and run batteries of tests on patients鈥� blood, sputum and other body fluids to pin down the microorganism responsible.
The syndrome is characterised by high fever, coughing and shortness of breath, often followed by life-threatening pneumonia. Investigators now estimate the incubation period to be between 2 and 7 days, although that may change as they discover more. 鈥淲e鈥檙e right now probably identifying the most severely ill patients, and so we want to be open to modifying that,鈥� says Julie Gerberding, director of the US Centers for Disease Control and Prevention.
Slightly more is known about how the disease is transmitted. In Hong Kong, one of the worst-hit regions, most people infected have been healthcare workers or family members of those with the disease already. This suggests that close, sustained contact is necessary, and that the disease is spread by droplets in the air produced when patients cough or talk.
Hong Kong was the centre of another disease outbreak last month (快猫短视频, 1 March, p 5), when two people who had arrived from elsewhere in China became infected with the H5N1 鈥渂ird flu鈥�. That outbreak raised fears of a possible flu pandemic, like the one in 1918 and killed at least 20 million people. At first the SARS outbreak was at first thought to be related, but as time goes on without a flu virus being identified in any SARS patient this is looking increasingly unlikely.
Nonetheless, the new infection has several worrying parallels with an influenza outbreak, says Gerberding. It is easily spread at close quarters, and is emerging in a part of the world where crowded living conditions encourage epidemics and from where international travel could spread the disease worldwide. 鈥淚t鈥檚 a wake-up call,鈥� she says.