WHO says SARS outbreak is contained, but cause still unclear

May 18, 2004 (CIDRAP News) The World Health Organization says China's latest SARS (severe acute respiratory syndrome) outbreak appears to be contained after nine cases, but its precise origin is still a mystery.

Because more than 3 weeks have passed since the last patient was isolated, the chain of transmission apparently has been broken, the WHO said in a statement today. But WHO and Chinese experts investigating a Beijing virology laboratory where two SARS patients worked have been unable to pinpoint how the outbreak started, the agency said.

A 26-year-old woman surnamed Song became ill in late March after working in a lab at the National Institute of Virology for 2 weeks, and a 31-year-old man who worked in the lab fell ill in mid-April. Research on the SARS virus was done in the lab, but the two patients never worked with live virus, the WHO has said.

"Preliminary findings in the investigation have yet to identify a single infectious source or single procedural error at the Instituteand it is conceivable that an exact answer may never be determined," the WHO said today.

However, the agency said investigators "have serious concerns about biosafety procedures at the Instituteincluding how and where procedures using SARS coronavirus were carried out, and how and where SARS coronavirus samples were stored."

The WHO urged all member countries to review the biosafety practices of labs that work with the SARS virus. The agency said many specimens were collected during and after the 2003 SARS outbreaks, and some are stored in labs with "inappropriate" containment measures. The WHO recommends biosafety level 3 as the minimum rating for labs handling the virus.

The agency commended Chinese authorities "for taking swift action to contain the latest outbreak once it was recognized and reported, by way of extensive contact tracing and the quarantine and medical observation of such individuals. Once again, it has been demonstrated that SARS is a containable disease."

The nine cases in the outbreak included one death, that of Song's mother. Except for the 31-year-old man who also worked in the lab, all the cases were traced directly or indirectly to Song. A 20-year-old nurse surnamed Li caught the virus from Song, and it subsequently spread from Li to several members of her family and other contacts. All but two surviving patients in the outbreak had been released from hospitals by May 12.

Hundreds of people were quarantined during the outbreak. A Reuters report today said 28 staff members from the virology institute were still in quarantine.