SARS (Severe Acute Respiratory Syndrome) is an infectious disease caused by a coronavirus. Coronaviruses, so named for the crown or halo surrounding them, usually cause mild illnesses such as the common cold. The coronavirus that causes SARS is more virulent, and was unknown until a worldwide outbreak of the disease in 2002–03.
How Does SARS Spread?
The SARS virus spreads in respiratory droplets from sneezes and coughs to people in close contact with an infected person. Close contact includes living with, looking after, or being in physical contact with an infected person. The virus may also spread in other ways that are not yet known. The incubation period, or length of time between exposure to the virus and signs of the first symptoms, is usually 2 to 7 days, but up to 14 days in some cases. SARS is thought to be contagious only once symptoms have begun.
What Are the Symptoms of SARS?The initial symptom of SARS is a high fever (>38ºC). Infected people may also experience a headache, muscular aches, shortness of breath, a dry cough, and diarrhea. Because the symptoms of SARS are common to other respiratory infections such as influenza, diagnosing SARS is difficult. A rapid diagnostic test is not available, so doctors assess possible cases for a combination of high fever, other symptoms, and chest X-rays showing respiratory distress that is consistent with SARS infection. There is no treatment specific for the SARS virus, but infected people are treated in the same way as patients with viral pneumonia. In some cases, SARS is fatal. Currently there is no cure or safe and effective vaccine for SARS, but scientists around the world, including in Canada, have tested antiviral drugs as possible treatments and have worked on developing a vaccine.
Global SARS Outbreak of 2002–03The first case of SARS was reported in China in November 2002. The virus then spread to over 20 countries, including Canada. The ease of global travel aided the rapid spread of this new infectious disease. Human-to-human spread of SARS was declared to have stopped in July 2003. During the outbreak period, from 1 November 2002 to 31 July 2003, 8,096 people were infected, 774 of whom died, according to the World Health Organization. In Canada, the outbreak began in March 2003 among people who had travelled to Hong Kong. During the outbreak, thousands of Canadians were quarantined and the World Health Organization issued a travel advisory for Toronto. In total, there were 438 probable cases of SARS in Canada, resulting in 44 deaths. In early 2004, China reported another SARS outbreak; it was contained without spreading outside the country.
The origin of the SARS virus is unclear. Scientists with the World Health Organization, however, have linked SARS with civet cats, members of the mongoose family that are a delicacy in parts of China and may be carriers of the SARS virus.