The recent case of severe acute respiratory syndrome (SARS) in Singapore was the result of a laboratory accident, so concludes an 11-member review panel led by Antony Della-Porta, Biosafety Expert for the WHO, in a report produced for the Ministry of Health in Singapore. Authorities in Singapore have continued surveillance for SARS since the last reported case in May 2003 and became alarmed when, at the end of August, a 27-year-old doctoral student at the Singapore General Hospital (SGH) developed symptoms consistent with SARS.
The student was working on West Nile virus samples at the BSL-3 laboratory, SGH 3·5 days before onset of illness, a time consistent with the SARS incubation period. Although no SARS work was being done that day, live SARS was definitely in the laboratory 2 days earlier. Stool and sputum samples tested for SARS coronavirus using reverse transcriptase polymerase chain reaction were positive and SARS infection was confirmed by the US Centers for Disease Control and Prevention. The frozen specimen that the student had worked on was positive for both the SARS coronavirus and West Nile virus, suggesting contamination.
The panel concluded that “inappropriate laboratory standards and a cross-contamination of West Nile virus samples with SARS coronavirus in the laboratory led to the infection of the doctoral student”. Their investigation showed that because Department of Pathology BSL-2 laboratories were being renovated, mixed BSL-2/BSL-3 activities were in progress in the BSL-3 facility, which jeopardised good safety practices. Deficiencies were identified at other BSL-3 laboratories and the report recommends that BSL-3 work in Singapore cease until these have been addressed. “The report of the review panel indicates both structural and functional deficiencies in Singapore's BSL-3 facilities”, comments Paul McKinney, Professor of Medicine and Public Health at the Center for the Deterrence of Biowarfare and Bioterrorism (University of Louisville, KY, USA). Of the two factors, practices are more important; BSL-3-level procedures should provide a sufficient margin of safety in handling the SARS virus. “There is a need for more precisely defined and internationally applicable standards to govern operations at such laboratories”, he says. James Snyder, Professor of Microbiology at the same institute, agrees and stresses that “it is essential that laboratories in all countries achieve and maintain laboratory certification standards”. Consideration should also be given to certification of personnel, which should involve periodic written and direct observation-based examinations, Snyder adds.