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Acute Respiratory Illness Outbreak in Canada

20 August 2003

Dear Doctor,

I would like to bring your attention to an acute respiratory illness outbreak in a long-term care facility in British Columbia in Canada. The outbreak started in early July 2003, and up to 14 August, affected 97 of 142 residents and 46 of 160 staff there.

Based on information we obtained from the Canadian health authority, the illness has been relatively mild. Symptoms have been predominantly upper respiratory and included rhinitis, cough, sore throat, and myalgia. Fever has not been a prominent symptom, only present in approximately 10% of staff and residents; a few residents have had diarrhea or nausea. The incubation period appears to be 5-7 days. Thirteen residents have been hospitalized, at least 4 of whom were hospitalized with illness not related to the outbreak. There have been a total of 7 deaths during the outbreak, all among frail elderly individuals and at least two of which were unrelated to the outbreak. The outbreak is currently resolving.

PCR and serologic tests performed by the National Microbiology Laboratory in Winnipeg revealed some patients' specimens were positive for a virus similar to the SARS coronavirus (SARS-CoV).

In summary, there is an outbreak of acute respiratory illness in a nursing home in British Columbia which clinically is not compatible with SARS, but in which there is laboratory evidence of SARS-CoV infection. Possible explanations include a newly identified less virulent variant of coronavirus or a mild form of SARS-CoV infection. Confirmatory testing including gene sequencing is ongoing.

Please also note that the World Health Organization has revised the clinical case definition of SARS for public health purposes as follows:

A person with a history of fever (38^oC or above)
AND
one or more symptoms of lower respiratory tract illness (cough, difficulty breathing, shortness of breath)
AND
Radiographic evidence of lung infiltrates consistent with pneumonia or Respiratory Distress Syndrome (RDS) OR autopsy findings consistent with the pathology of pneumonia or RDS without an identifiable cause.
AND
No alternative diagnosis can fully explain the illness.

The Department of Health will closely monitor the situation and keep you posted of new development. In view of the Canadian experience, please maintain due vigilance in infection control measures in your health care facility, maintain good staff sickness records, and report to the Department of Health of any suspected acute respiratory illness outbreak (even those with relatively mild symptoms) for further investigations.

Advice and information for health care professionals can be found in the DH website: 这连结会以新视窗打开。http://www.chp.gov.hk/en/guideline_infection/346.html

For prevention of respiratory tract infection, please advise your clients to adopt the following measures:

Build up good body immunity by having a proper diet, regular exercise and adequate rest, reducing stress and avoiding smoking;
Maintain good personal hygiene, and wash hands after sneezing, coughing or cleaning the nose;
Maintain good ventilation;
Avoid visiting crowded places with poor ventilation;
Consult a doctor promptly if they develop respiratory symptoms; and
Put on a mask if suffering from respiratory tract infection to reduce the chance of spreading the infection to people around them.

	Yours faithfully, (Dr Marina Sum)
for Director of Health