Medical Information

What is SARS?

Severe Acute Respiratory Syndrome (SARS) is a type of highly contagious pneumonia caused by a previously unknown virus, a so called 'atypical pneumonia". Other causes of "atypical pneumonia" are influenza, Chlamydia, mycoplasma and other viruses.
"Typical" pneumonia is caused by more common organisms such as bacteria like streptococcus.

CASE DEFINITION OF SARS;
Clinical case definition of SARS:

A person with a history of

Fever of 38^oC or higher
AND
One or more symptoms of lower respiratory tract illness (cough, difficulty breathing, shortness of breath)
AND
X-ray evidence of pneumonia or respiratory distress syndrome (RDS) OR autopsy findings consistent with pneumonia or RDS without an identifiable cause
AND
No alternative diagnosis can fully explain the illness.

Laboratory case definition of SARS

A person with symptoms and signs that are clinically suggestive of SARS AND with positive laboratory findings for SARS-CoV based on one or more of the following diagnostic criteria: (testing should only be undertaken in a national or regional reference laboratory as per WHO recommendations)

a. PCR positive for SARS-CoV
Validated from :

At least 2 different clinical specimens
OR
The same clinical specimen collected on 2 or more occasions during the course of the illness
OR
2 different assays or repeat PCR using a new RNA extract from the original clinical sample on each occasion of testing.

b. Seroconversion by ELISA or IFA

Negative antibody test on acute serum followed by positive antibody test on convalescent phase serum tested in parallel
Fourfold or greater rise in antibody titre between acute and convalescent phase sera tested in parallel.

c. Virus isolation

Isolation in cell culture of SARS-CoV from any specimen
AND
PCR confirmation using a validated method.

DOES SUBCLINICAL OR ASYMPTOMATIC INFECTION OF SARS EXIST?

Canada reported SARS corona virus positivity and seroconversion in persons who do not meet the case definition for SARS.
In Hong Kong, 32 of 316 asymptomatic contacts of SARS cases from Amoy Gardens had laboratory evidence of SARS-CoV in their respiratory secretions and stool by PCR test. Only 1 of 161 asymptomatic Amoy Garden residents tested while under isolation in the holiday camps was seropositive and PCR positive.
China also reported some asymptomatic health care workers exposed to SARS cases
Had serological evidence of SARS CoV infection

Close Contact means

Having cared for or
Having lived with or
Having had direct contact with respiratory secretions and body fluids of a person with SARS

Social Contact means, you have not lived with, cared for or worked closely with a suspected or confirmed case of SARS but you may have had brief social encounters with a suspected or confirmed case of SARS.
This type of encounter is unlikely to be high risk.

HKU criteria of reporting SARS cases

"Confirmed" Case:

Cases admitted into SARS ward of HA hospitals and reported to HA SARS Registry.*

Suspected Case:

Cases admitted into suspected SARS case ward of HA hospitals.

* Criteria for reporting to HA SARS Registry (22/4/2003)

Radiographic evidence of infiltrates consistent with pneumonia, and
Fever >38^oC or history of such at any time in the past 2 days, and
At least 2 of the following :
1. History of chills in the past 2 days
2. Cough (new or increased cough) or breathing difficulty
3. General malaise or myalgia
4. Known history of exposure

Exclusion criteria
A case should be excluded if an alternative diagnosis can fully explain their illness

Exclusion criteria
Does not completely fulfil the above definition but still considered to be highly likely of SARS on clinical judgment

Close Contact :

To protect the University community from getting infected within the University, we adopt an extra cautious approach in applying this principle to University staff or students :

Close contacts are those who have been working in a small confined area with a suspected or confirmed case or who have had prolonged hours of face to face interaction at close distance with the suspected or confirmed case.

Social contacts are those who have engaged in relatively brief hours of social contact with a suspected or confirmed case.

Remote social contacts are those who have been in the same room as the suspected or confirmed case for brief hours without any social interaction..

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