According to the U.S Centers for Disease Control (CDC) SARS is a respiratory illness that was first reported   among people in Guangdong Province (china), Hanoi (Vietnam), Hong Kong (Special Administrative Region of   China), with the first reported case occurring on February 1, 2003. It has since spread to other countries.

 Two types of virus in particular appear to be candidates. The first is a virus in the family of coronaviruses.This   family of viruses is a common cause of mild upper respiratory tract infections and can also produce intestinal   infections as well as, possibly, infections of the brain.

It is believed that the virus from the patient can be passed like other respiratory diseases such as the common cold or flu. When the infected patient coughs or sneezes, tiny body fluid containing viruses travel through the air and contaminate the surroundings. When people inhale the air or touch the infected vehicles (this can be coffee cup, door knob, pen, etc.), there is a chance of catching the disease.

The Virus for SARS has an incubation period of between 2 to 7 days, possibly as many as 10 days. It seems that patients are most likely to be infections when they have symptoms, such as fever or cough. It is not known for sure whether patients are infections during the incubation period or after their symptoms have subsided.

Cases of SARS continue to be reported primarily among people who have had direct close contact with an infected person, such as those sharing a household with a SARS patient and health care workers who did not use infection control procedures while caring for a SARS patient. In the United States, there is no indication of community transmission at this time. CDC continues to monitor this situation very closely. 

So far, symptoms manifesting in SARS are similar with that of other respiratory diseases such as atypical pneumonia, so that it is hard to tell SARS from other similar infections.