One of the first indications that SARS had emerged in Asia was a posting circulated by ProMED-mail (Program for Monitoring Emerging Diseases), an email list moderated and maintained by the International Society for Infectious Diseases and the Harvard School of Public Health. As described on its website (www.promedmail.org), ProMED-mail is essentially an early warning system for emerging threats, “an internet-based reporting system dedicated to rapid global dissemination of information on outbreaks of infectious diseases and acute exposures to toxins that affect human health.”1 ProMED-mail provided the first description of the unusual pneumonia-like condition that later became known as SARS. On 10 February 2003, ProMED-mail disseminated a posting with the subject line “Pneumonia-China (Guangdong): RFI [request for information]”:
This morning I received this e-mail and then searched your archives and found nothing that pertained to it. Does anyone know anything about this problem? "Have you heard of an epidemic in Guangzhou? An acquaintance of mine from a teacher's chat room lives there and reports that the hospitals there have been closed and people are dying."
—Posted on ProMED-mail by Stephen O. Cunnion, M.D.2
2003 SARS Outbreak in Asia and Canada
Figure 1. Adapted from (1), Varia et al.,Investigation of a nosocomial outbreak of severe acute respiratory syndrome (SARS) in Toronto, Canada. CMAJ 2003 Aug;169(4):285-292. www.cmaj.ca
At the same time that unusual pneumonia-like activity in parts of Asia was being described on ProMED-mail and elsewhere, the chain of events that would lead to the Canadian outbreak began to unfold. The first patient became ill on 16 November 2002 in Guangdong province, although this was not established as the global index case until several months later. This case was followed by a cluster of atypical pneumonia cases in the region between November and February 2003. A doctor who had treated some of the atypical pneumonia patients in Guangdong province travelled to Hong Kong to attend a wedding on 21 February (Figure 1).3 He was staying at the Metropole Hotel when he began to develop symptoms. In less than 24 hours, the illness spread to approximately a dozen other hotel guests, including a 78-year old woman from Canada who was in Hong Kong on holiday.
This woman would later become the Canadian index case. Upon returning home to Toronto on 23 February, the woman started to develop symptoms, and on 5 March 2003 she died of unrecognized SARS. Transmission to a family member who was later admitted to a community hospital in Toronto led to a large nosocomial outbreak. Subsequently, the transmission chain from the Canadian index case resulted in at least 6 generations of transmission, 4 of which were due to nosocomial spread (Figure 1).3
On 23 April 2003, after the first peak of the SARS outbreak, WHO recommended that travellers only visit Toronto if a trip was absolutely essential. This followed a similar travel advisory issued for Hong Kong and China’s Guangdong province on 2 April. The travel advisory had a devastating economic and social impact on Toronto. Tourism sustained a $350 million loss and retail sales declined by $380 million compared with usual seasonal business.5 Not surprisingly, the travel advisory was controversial.6 The advisory was lifted just a few days later on 30 April, when the last presumed SARS case was diagnosed.
The SARS outbreak was believed to be over in early May 2003, when no new cases had been identified after two incubation periods. Consequently, the enhanced infection control practices that had been implemented were observed less strictly, along with the many rules concerning protective gear and limitations on hospital visitors and procedures. However, on 23 May public health officials announced that five people were under investigation for SARS, and this ultimately led to a second phase of the outbreak, “SARS II.” Infection control precautions were reinstituted and control of transmission was achieved promptly.7
- 1. ProMED-mail. About ProMED-mail. Brookline, MA, USA: International Society for Infectious Diseases; 2010. http://www.promedmail.org/aboutus/
- 2. ProMED-mail. Pneumonia–China (Guangdong): RFI. ProMED-mail archive 20030210.0357. Brookline, MA, USA: International Society for Infectious Diseases; 2003 Feb 10. http://www.promedmail.org.
- 3. a. b. c. Varia M, Wilson S, Sarwal S, McGeer A, Gournis E, Galanis E, Henry B; Hospital Outbreak Investigation Team. Investigation of a nosocomial outbreak of severe acute respiratory syndrome (SARS) in Toronto, Canada. CMAJ 2003 Aug;169(4):285-292. http://www.cmaj.ca/content/169/4/285.full
- 4. National Advisory Committee on SARS and Public Health, Naylor D. Learning from SARS: renewal of public health in Canada: A report of the National Advisory Committee on SARS and Public Health. Chapter 2. Ottawa: Health Canada; 2003. http://www.phac-aspc.gc.ca/publicat/sars-sras/naylor/. The reproduction is a copy of an official work that is published by the Government of Canada and that the reproduction has not been produced in affiliation with, or with the endorsement of the Government of Canada.
- 5. a. b. National Advisory Committee on SARS and Public Health, Naylor D. Learning from SARS: renewal of public health in Canada: A report of the National Advisory Committee on SARS and Public Health. Ottawa: Health Canada; 2003. http://www.phac-aspc.gc.ca/publicat/sars-sras/naylor/
- 6. Paquin LJ. Was WHO SARS-related travel advisory for Toronto ethical? Can J Public Health. 2007;98(3):209-211. http://journal.cpha.ca/index.php/cjph/article/view/814/814
- 7. Ofner-Agostini M, Wallington T, Henry B, Low D, McDonald LC, Berger L, Mederski B, the SARS Investigative Team, Wong T. Investigation of the second wave (phase 2) of severe acute respiratory syndrome (SARS) in Toronto, Canada. What happened? Canada Communicable Disease Report. Public Health Agency of Canada. 2008 Feb;34(2):1-11. http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/08vol34/dr-rm3402a-eng.php