Causative Agent
SARS-associated coronavirus (SARS-CoV)
Incubation Period
Typically 2-7 days but may be prolonged up to 10-14 days
Infectious Period
Throughout the symptomatic phase of the disease.
Although there may be persistent viral shedding in the stool for up to 6 weeks after recovery from clinical illness, transmission of the disease has not been documented from asymptomatic nor convalescent individuals.
Transmission
Respiratory droplets and less often by direct contact with objects contaminated by respiratory secretions. Oral-faecal and airborne transmission may occur under special circumstances.
Epidemiology
The first outbreak of this new infectious disease occurred in Guangdong, China in November 2002, but soon spread to several Asian countries and Canada by March 2003. The outbreak ended on 5th July 2003, although two cases attributed to laboratory transmission were reported from Singapore and Taiwan in September and December 2003, respectively. Another laboratory associated outbreak occurred in China in April 2004.
The majority of transmission occurred in hospitals and other institutional healthcare settings.
By the end of the worldwide outbreak in July 2003, a total of 8096 cases were reported, with 774 deaths and a case-fatality rate of 9.6 percent.
Between March and May 2003, a total of 238 cases, with 33 deaths, were reported in Singapore. 41% of the cases were healthcare workers, and 68% were females. The median age of all SARS cases was 36 (range 4 to 90) years.
Chest X-ray. This may be normal early in the course of the disease. However, the more distinct radiographic features include:
- A predominantly peripheral location of air-space opacity
- Progression from unifocal to multifocal or bilateral lung involvement during treatment; and lack of cavitation, lymphadenopathy and pleural effusion.
- All suspected and probable/confirmed cases of SARS will be isolated and treated at the Communicable Disease Centre (CDC).
- Symptomatic and supportive treatment for all cases.
- Ribavirin which was used initially during the pandemic has been shown to be ineffective in vitro towards SARS coronavirus and is associated with significant toxicities.
- Some centres recommend a short course of moderate to high dose corticosteroids.
- There may be a role for treatment using protease inhibitor like lopinavir, immunoglobulins and interferon based on prior experience.
