SARS is a new disease in human beings, first recognised in late February, 2003, in Hanoi, Vietnam. The severity of the disease, combined with its rapid spread along international air-travel routes, prompted WHO to set up a network of scientists from 11 laboratories around the world to try to identify the causal agent and develop a diagnostic test. The article outlines how this network unites laboratories with different methods and capacities to rapidly fulfil all criteria for establishing a virus as the cause of a disease. Results are shared in real time via a secure website, on which microscopy pictures, protocols for testing, and polymerase chain reaction (PCR) primer sequences are also posted. Findings are discussed in daily teleconferences. Progress is further facilitated through sharing between laboratories of samples and test materials. The network has identified a new coronavirus, consistently detected in samples of SARS patients from several countries, and conclusively named it as the causative agent of SARS; the strain is unlike any other known member of the genus coronavirus.
Lead Author Klaus Stohr from WHO comments: "Three diagnostic tests are now available, but all have limitations. Since one test detects antibodies reliably only from about day 20 after the onset of clinical symptoms, it cannot be used to detect cases before they potentially spread the infection to others. The second test, an immunofluorescence assay, detects antibodies reliably after day 10 of infection. Various versions of real-time and block-based PCR tests are currently being developed to improve their low sensitivity and reduce the number of false-negative test results. All existing tests, used individually or in combination, can only confirm the disease in suspected or probable SARS cases. More work is needed before reliable, easy-to-use and sensitive tests become available in all countries. Work towards this objective is continuing and is proceeding at a rapid pace. Each laboratory has contributed substantially to the rapid identification and characterisation of the new coronavirus associated with SARS."
This paper is published in memory of Carlo Urbani, a WHO staff member who died of SARS.
Contact: Dr Klaus Stohr, Project Leader Influenza, NCS, Dept of Communicable Disease, Surveillance & Response, WHO, CH-1211, Geneva 27, Switzerland;
T) 41-22-791-4997/2529;
F) 41-22-791-4878/4498;
E) stohrk@who.int
Journal
The Lancet