SARS first occurred in Guangdong, China in 2002, and spread worldwide the following year. By the end of July 2003, a total of 8,096 cases were reported in 29 countries, with 774 deaths, representing a Case Fatality Rate of 9.6%.

In Singapore, 238 cases with 33 deaths were reported in March to May 2003. The median age of all cases was 36 (ranging from 4 to 90) years; 41% of infections involved healthcare workers. Subsequent laboratory-acquired infections were reported in 2003 (Singapore and Taiwan) and 2004 (China).

Pathogen(s)

SARS coronavirus (SARS-CoV)

Transmission

SARS primarily transmits through inhalation or direct deposition of infectious respiratory particles (IRPs) such as when an infected person coughs or sneezes. It can also spread via contact with contaminated surfaces such as when IRPs settle on surfaces or transfer through direct contact (e.g. handshake) before reaching the mouth, nose or eyes.

Incubation period: Typically 2 to 7 days; ranging from 1 to 14 days.

Infectious period: Throughout the symptomatic phase of the disease, usually less than 21 days. Though rare, there may be persistent viral shedding in the stool for up to 6 weeks after onset of clinical illness, but transmission of the disease has not been documented from asymptomatic nor convalescent persons.

Clinical features

The clinical presentation is non-specific and resembles other influenza-like illnesses. The prodrome lasts 3 to 7 days and is characterised by fever, malaise, headache and myalgia. Respiratory symptoms and diarrhoea, if present, typically occur a few days after the onset of fever. Physical examination is not helpful except as a gauge of severity of illness.

Clinical manifestations vary from mild infection (80%) to severe disease (20%) with respiratory failure and death. Death is usually caused by a combination of respiratory and multiorgan failure. The clinical course is marked by deterioration in the second week of illness and recovery by the third week in the majority of cases. Children have a shorter and milder course of illness. There is no evidence at present of intra-partum infection.

Chest X-ray 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 a lack of cavitation, lymphadenopathy and pleural effusion.

Risk factors

Risk factors include:

Relevant travel history to areas with reported cases or transmission of SARS
Contact with confirmed or suspect cases, especially in healthcare facilities

Diagnosis

Detection of SARS-CoV in respiratory samples including throat and nasopharyngeal swabs, endotracheal aspirate and bronchoalveolar lavage through Polymerase chain reaction, sequencing, virus isolation or four-fold rise in antibody titres.

Treatment and management

Clinical management is symptomatic and supportive treatment for all cases. Ribavirin which was initially used during the pandemic has been shown to be ineffective in vitro. There is no clinical evidence of the effectiveness of ribavirin against SARS-CoV, and its use is associated with significant toxicities. Other treatments used were corticosteroids, lopinavir, immunoglobulins and interferon, although conclusive evidence of benefit is lacking.

Precaution, prevention, and control

Isolation measures

Suspect SARS patients seen at the outpatient settings should be isolated or segregated from the other patients in the clinic, where possible, and be given a surgical mask to wear if experiencing respiratory symptoms prior to the transfer to an airborne infection isolation room (AIIR) in the hospital. All suspect or confirmed SARS patients should be isolated in AIIRs.

Standard, contact and airborne precautions are recommended when attending to suspect or confirmed SARS patients. Full PPE (gown, gloves, eye protection, and N95 mask) is required when treating suspect or confirmed SARS patients.

Contact management

In the case of exposure to an infected person, exposed persons should immediately seek advice from an Infectious Diseases physician and report the exposure to the Ministry of Health.

Close contacts will be contact traced by the Communicable Diseases Agency and appropriately followed up (e.g., quarantine, phone surveillance or self-monitoring).

Vaccination

There is currently no available vaccine for SARS.

Notification

SARS is a legally notifiable disease in Singapore.

Who should notify:

Medical practitioners
Laboratories

When to notify:

On clinical suspicion or laboratory confirmation

How to notify:

Please refer to the Infectious Disease Notification for more information.

Notification timeline:

Immediately. No later than 24 hours.

Resources

Please refer to the Weekly Infectious Diseases Bulletin for the number of SARS cases in Singapore.

For more information on SARS, please refer to the World Health Organization website.

For general travel advisory, please refer to Health Advice for Travellers.