For the third time in less than a year, an outbreak of severe acute respiratory syndrome (SARS) seems to have originated from a failure in laboratory containment. This latest incident, revealed in China late last week, is the most serious. One death is tentatively attributed to it, eight people are confirmed or suspected of contracting the disease, and hundreds have been quarantined.
The apparent lapse is especially troubling because it occurred in China's leading SARS research lab, at the Center for Disease Control and Prevention (CDC) in Beijing. Also disturbing, experts say, is that one lab worker traveled widely while she had symptoms of the disease. Despite that lapse, Chinese authorities now seem to have the situation under control, says Robert Dietz, spokesperson for the Beijing office of the World Health Organization (WHO). The two earlier lab accidents, in Singapore in September (ScienceNOW, 10 September) and Taiwan in December (ScienceNOW, 17 December), did not result in spread beyond the affected workers.
Two of the Chinese cases, a 26-year-old graduate student identified by her surname, Song, and a 31-year-old male postdoc named Yang were both apparently exposed in the same lab at the Institute of Viral Disease Control at the Chinese CDC. But Dietz says that the onset of symptoms likely indicates two separate exposure events. Song developed SARS symptoms on 25 March; Yang, on 17 April. The prospect of two separate exposure incidents suggests "some sort of systemic or procedural failures" in the lab, Dietz says. But he warns against any conclusion until the origin of the infections is confirmed.
Regardless of the source, the outbreak may show "a failure in applying guidelines to monitor the health of the people who work in these labs," Dietz says. After working in the lab in Beijing, Song returned home to Anhui Province. When she developed a fever, she traveled to Beijing by train, where she was treated at a hospital and released. Accompanied by her mother, she returned to Anhui by train, entered a different hospital, and was later transferred to a third. On 19 April her mother died of pneumonia, presumably a SARS victim. A nurse who attended Song at the Beijing hospital contracted SARS and has apparently spread the infection to several members of her family.
Authorities have now closed the virus lab, and more than 200 institute employees have been quarantined. Another 400 who had contact with suspected SARS cases have also been quarantined. Dietz says WHO expects to have a team of biosafety experts in Beijing this week to help the Ministry of Health try to pin down the source of infection.