Cause: SARS is caused by viruses from the corona and paramyxo virus family. Corona usually causes common cold. Incubation period (time taken for infection to cause symptoms) is two to seven days, starting with fever and cough, after which patients might suffer from severe difficulty in breathing, chest pain.
Origin: Geographically, the outbreak seems to centre around China's Guangdong province near Hong Kong. From an epidemiological standpoint, no one knows where SARS comes from, where it began, or how it infected its first victim.
Symptoms: Initially fever (over 100 degree fahrenheit), headache, sore throat and cough; leading to breathlessness due to pneumonia that may be fatal.
How infectious is it? Very. Spreads through air and/or droplets released from sneezing, coughing; also possibly through contact with contaminated objects (door handles, towels, for example).
At risk: Those in contact with the infected, travellers to SARS-affected countries. China, Hong Kong, Singapore, Vietnam, the United States and Canada are the worst hit.
Precautions: Extremely difficult to diagnose SARS in early stage even by experienced doctors since it mimics cold and flu-like disorders. Therefore, first and foremost, suspected SARS patients must be isolated. Those in contact with patients should wash hands often, use alcohol-based hand rubs, must wear a mask.
Treatment: No definitive treatment yet; antibiotics ineffective; anti-virals, steroids, medicines for high fevers (paracetamol, for example) being used, patients being put on respirators if they develop respiratory distress.