Scientists at the Centers for Disease Control and Prevention (CDC) and other laboratories have detected a previously unrecognized coronavirus in patients with SARS. Coronaviruses are a group of viruses that have a halo or crown-like (corona) appearance when viewed under a microscope. These viruses are a common cause of mild to moderate upper-respiratory illness in humans and are associated with respiratory, gastrointestinal, liver, and neurologic disease in animals.
For a severe respiratory illness to be SARS, there has to be a history of travel to a SARS-affected area, or close personal contact with a person with SARS, within 10 days before symptoms start.
In general, SARS begins with a high fever (temperature greater than 100.4F [38.0C]). Other symptoms may include headache, an overall feeling of discomfort, and body aches. Some people also have mild respiratory symptoms at the outset. About 10 to 20 percent of patients have diarrhea. After two to seven days, patients develop a dry cough, shortness of breath, and pneumonia.
SARS is spread primarily by close person-to-person contact. The virus that causes SARS is spread through respiratory droplets produced when an infected person coughs or sneezes. The virus also can spread when a person touches a surface or object contaminated with these infectious droplets and then touches his or her mouth, nose or eyes.
In the context of SARS, close contact means having cared for or lived with someone with SARS or having contact with respiratory secretions of a patient with SARS. Examples of close contact include: kissing or hugging, sharing eating or drinking utensils, or sustained interaction within 3 feet of someone infected with SARS. Close contact does not include walking by an infected person or sitting across from an infected person for a short period of time.
After exposure to SARS, the incubation period is two to 10 days.
Individuals suspected of having SARS should avoid contact with others, including staying home from work, school or day care, during their illness and for 10 days after their symptoms have disappeared.
Only those who have signs and symptoms consistent with SARS need to be restricted from normal activities.