Canadian Environmental Health Atlas

Understanding Our Environment is Key to Promoting Health and Preventing Disease

Search form

SARS: Severe Acute Respiratory Syndrome

SARS: Severe Acute Respiratory Syndrome

First Emerging Infectious Disease of the 21st Century
The story of the 2003 outbreak of severe acute respiratory syndrome (SARS) is familiar to many Canadians. SARS is an atypical pneumonia caused by infection with a coronavirus (Figure 1).1 A highly infectious droplet-spread illness, SARS first emerged in Guangdong province in southern China in November 2002. In less than a year, cases were identified in 26 countries, demonstrating how fast an emerging infection can be spread by international air travellers.

Globally, approximately 8500 people were diagnosed with probable SARS during the outbreak, and over 900 people died.2 Outside of Asia, Toronto experienced the greatest impact. Ultimately, control efforts were successful and the outbreak was declared over in July 2003.

Mapping SARS
As well as prompting public health practitioners to improve on old practices and develop new ones throughout the outbreak, SARS prompted scientists from many disciplines to use geographic mapping technology and novel geographic information system (GIS) applications to track the disease.

During the global spread of SARS, the World Health Organization (WHO) posted maps on the Internet each week to show the worldwide distribution of the infection (Figure 2).3 At a local level, some jurisdictions provided the public with GIS applications to disseminate information about SARS. The Hong Kong Yellow Pages website provided detailed interactive SARS maps that allowed users to zoom in on buildings where infection was active or suspected (Figure 3).4Users could type a location into a text box on the site to find the nearest five infected buildings. Similarly, a Hong Kong mobile phone company, Sunday Communications Ltd, launched a mobile message service to notify subscribers when they were approaching a risky area. Users could access calling-area information and determine if they were within one kilometre of a building where the presence of SARS cases was suspected or confirmed.4

Epidemiology of SARS
   • The incubation period is 2 to10 days.5
   • Transmitted mainly through respiratory droplets and direct contact.
   • Symptoms include fever, cough, and shortness of breath.
   • Many symptoms are non-specific and similar to other respiratory illnesses, making
     SARS difficult to diagnose.
   • Maximum infectivity occurs in the second week of illness.6
   • Primarily transmitted in hospitals (nosocomially) through staff and visitor contact
     with infected patients.7
   • The case fatality rate in Canada was about 15%.89
   • The majority of people who died were older or had other medical conditions.

Outbreak Timeline, 2002–200310
   • 16 November 2002 – First known case of atypical pneumonia occurs in Guangdong province, China.
   • 11 February 2003 – China reports the outbreak to the World Health Organization (WHO).
   • 26 February 2003 –  First case of unusual pneumonia reported in Hanoi, Vietnam.
   • 12 March 2003 –  Report of mysterious respiratory disease contracted by Hong Kong hospital staff.
      WHO issues first global alert about unnamed disease.
   • 15 March 2003 – WHO issues second global alert, using the term “severe acute respiratory syndrome.”
   • 26 March 2003 – SARS is declared a provincial public health emergency by the premier of Ontario.9
   • 23 April 2003 – WHO issues travel advisory for Toronto.
   • 30 April  2003 – WHO lifts travel advisory for Toronto.
   • 22 May 2003 – SARS II begins in Toronto.
   • 5 July  2003 – SARS outbreak declared to be over.