Summary of Severe Acute Respiratory Syndrome (SARS) Cases: Canada and International

March 31, 2003

Canada

Latest Case Counts: Since yesterday, nine additional probable cases have been reported in Canada. A total of 53 individuals who meet the probable case definition of SARS have been reported in Ontario and British Columbia, including 4 deaths. In addition, a total of 76 individuals who meet the definition of a suspect case of SARS have been reported in British Columbia, Alberta, Saskatchewan, Ontario and New Brunswick. Since SARS is a diagnosis of exclusion, the status of a reported case may change over time. Thus, previously reported cases may be discarded after further investigation and follow-up. The current number of probable cases by reported symptom onset date and type of exposure is also provided (Figure 1).

Recent Ontario Epidemiologic Findings: The Ontario Ministry of Health and Long-Term Care has reported a total of 51 probable cases of SARS. Of these, most remain hospitalised for isolation purposes and only two are currently in intensive care. All four deaths were associated with individuals with underlying illness, and all but one occurred in elderly patients. Using the information currently available, the average age of probable cases is 46.5 years (n=37, range 17 to 82 years), with 26 known females and 17 known males.

While it is difficult to conclusively determine the incubation period of the etiologic agent, given the fact that many of the probable cases in Ontario may have multiple exposures, the current estimated mean incubation period is 4 days (estimated range 2 to 10 days).

It is believed that four generations of transmission have occurred. The index case in Ontario was an individual who travelled to Hong Kong and stayed at the Metropole Hotel, where a cluster of SARS cases has since been reported. Upon return to Canada, disease transmission occurred in four members of the immediate and extended family. A physician who had close contact with members of this family was also diagnosed with SARS. Following this, cases were reported in individuals in a hospital setting where some of the first cases were treated. Most recently, SARS has been reported in a few of the household contacts of these hospital-associated cases. An isolated case in Ontario was reported in an individual who had travelled to Asia, but did not stay in at the Metropole Hotel.

Based on the most recent epidemiologic investigations, nearly all of the probable cases of SARS that occurred in individuals outside of the initial family cluster have been linked either directly or indirectly back to exposure to the first hospitalised case of SARS, on March 7, 2003. It is believed that disease transmission occurred mainly as a result of person-to-person contact. The initial hospital-associated cases are thought to have contracted the illness as a result of unprotected contact with the initial cases prior to the recognition of SARS. Subsequent transmission may have then occurred between households of these hospital-associated cases, and between other healthcare workers. To date, there has been no evidence of transmission in the general community. Furthermore, there is presently no evidence to suggest that disease transmission occurs prior to the onset of fever in a suspected or probable case of SARS.

Other Reports: A Canadian with SARS [not counted in the official Canadian case count], who is currently hospitalised in Hong Kong, stayed at the Metropole Hotel, as did the first identified probable case of SARS in British Columbia. However, while a second probable case reported by BC did not stay at this hotel, this individual was exposed to a SARS case while in Hong Kong. Both BC cases are currently in isolation and there is no evidence of further spread in the province. The 11 suspected cases currently under investigation are all associated with travel-related exposures.

Ontario has declared a provincial emergency and SARS is now a reportable diseases under Ontario's Health Protection and Promotion Act. The province has introduced a number of public measures in an effort to contain the spread of SARS. Key public health measures include: extensive contact tracing of persons who may have come in contact with SARS cases, isolation of suspect and probable cases, and voluntary home quarantine for asymptomatic contacts. Isolation wards have been established at hospitals and health care staff are required to observe full airborne and contact precautions. Health care staff across the province are now alerted to SARS and have implemented infection control practices to protect themselves and their patients in an effort to prevent any further infection.

Health Canada is supporting Ontario in its SARS response efforts by providing epidemiologic and infection control expertise, as well as emergency supplies as needed. Health Canada in collaboration with the Provinces and Territories has implemented enhanced surveillance for the detection of SARS cases, alerted laboratories and initiated special laboratory investigations in an effort to identify the cause of SARS. In addition, Health Canada is working quickly to implement a screening protocol for international travellers in response to the WHO recommendations to prevent travel-related spread of SARS. Due to recent concerns regarding the possibility of transmission of SARS aboard aircraft, Health Canada has also recommended follow-up of all passengers on flights where a suspect or probable SARS case is identified. For regular updates on public health actions taken by Health Canada, please see the most recent update

Table 1
Cumulative Number of SARS Cases Reported in Canada, March 31, 2003

Province/Territory	Individuals Meeting the Criteria for a:		Deaths
	Probable Case1	Suspect Case1
British Columbia	2	11	0
Alberta	0	5	0
Saskatchewan	0	1	0
Manitoba	0	0	0
Ontario	51	58	4
Quebec	0	0	0
Nova Scotia	0	0	0
Newfoundland	0	0	0
New Brunswick	0	1	0
Prince Edward Island	0	0	0
Nunavut	0	0	0
North West Territories	0	0	0
Yukon	0	0	0
TOTAL	53	76	4
1These persons may drop off the probable or suspect case list if another cause if identified for their illness

 

Figure 1: Number of probable cases of SARS in Canada by symptom onset date and exposure type from: February 23 to March 31, 2003
(n=38, excluding 15 for whom onset dates are missing)

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International

Since November 1, 2002, 1631 cases of SARS (1578 outside of Canada) have been reported to the World Health Organization (refer to Table 2). The majority of cases are reported from Guangdong Province and Hong Kong Special Administrative Region of China, Singapore and Hanoi, Vietnam with Hong Kong presently showing the greatest increase in cases. Due to the continued steep rise in the number of SARS cases detected in one apartment building in Hong Kong over the past few days, the WHO reported today that the Hong Kong Department of Health issued an unprecedented isolation order requiring the residents of this complex to remain quarantined at home for the next 10 days (www.who.int/csr/sarsarchive/2003_03_31/en). Cases of SARS in other parts of the world have occurred in persons or close contacts of persons who have travelled to these destinations. As of March 31, 2003, 54 deaths have been reported outside of Canada, the majority (34) of which were reported in Guangdong Province of China. The total number of cases and deaths in Guangdong was only recently reported in the WHO cumulative international total and included only data for the period November 16, 2002 to February 28, 2003.

As of March 25, a cluster of 13 persons with suspected or probable SARS are known to have stayed at the Metropole Hotel in Hong Kong. These cases subsequently became index cases in several countries, including Vietnam, Singapore, the United States, Ireland, and Canada (MMWR Vol 52, No. 12, March 28, 2003). The visitor from mainland China, a medical doctor from Guangdong Province who became ill a week before staying at the hotel, is considered to be the original source of the infection. No further cases have been linked to the hotel.

The majority of cases have occurred in people who have had very close contact with other cases including household contacts and health care workers.

The main signs and symptoms seen in cases of SARS include fever (>38.0 degrees Celsius), cough and shortness of breath. Symptoms of an upper respiratory tract infection may not be present. Some cases develop increasing respiratory distress and require mechanical ventilation. In the majority of hospitalised cases, an infiltrate on chest x-ray and lymphopenia is usually evident. In addition, thrombocytopenia (<150,000/mm3), elevated creatinine kinase and elevated ALT/AST may be observed. The WHO is coordinating global efforts to better characterize the clinical manifestations of SARS. Because awareness and surveillance of the disease have increased worldwide, an increase in the number of suspected cases is to be expected.

Table 2
Table 2 - Cumulative Number of SARS Cases* and Deaths Reported to WHO
November 1, 2002 to March 31, 2003

Country	Number of Cases	Number of Deaths
Canada	53	4
China, Guangdong Province	806**	34
China, Hong Kong SAR	530	13***
China, Taiwan	10	0
France	1	0
Germany	5	0
Italy	2	0
Republic of Ireland	2	0
Romania	3	0
Singapore	91	2
Switzerland	3	0
Thailand	5	1
United Kingdom	3	0
United States	59	0
Vietnam	58	4
TOTAL	1631	58
*Cumulative number of cases includes deaths. Case definitions vary from one country to another. Only probable cases are being reported by all countries except the US which is reporting suspect cases under investigation. ***This is an updated report of cases from 16 November 2002 to 28 February 2003 in Guangdong Province. The number of cases was compiled from investigations as well as hospital reports and may include suspect as well as probable cases of SARS. ***One death attributed to Hong Kong SAR occurred in a case medically transferred from Vietnam. Source: http://www.who.int/csr/sarscountry/2003_03_31/en/