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Severe acute
respiratory syndrome is caused by a viral infection and presents
with flu-like symptoms (fever, headache, chills, cough, and muscle
aches) and difficulty breathing, which sometimes becomes severe.
The infection can be fatal.
Severe acute respiratory syndrome (SARS) was first detected in the Guangdong province of China in late 2002. A worldwide outbreak occurred, resulting in almost 8500 cases in 29 countries, including Canada and the United States, by mid 2003. The outbreak spread to several countries because of international travel. After the initial outbreak, a few cases occurred in Asia (primarily China) in late 2003 and early 2004. As of mid 2006, no cases had been reported worldwide since 2004. Overall, about 10% of people with SARS die, although the risk of death varies with the person's age and access to advanced medical care. People older than 60 years are much more likely to die. No deaths have occurred in the United States.
SARS appears to be caused by a new type of coronavirus. Other coronaviruses cause common colds or infect various animals. SARS spreads through face-to-face contact, probably by inhaling droplets breathed or coughed out by infected people. It may also be spread by touching secretions of infected people and then touching the nose, mouth, or eyes. Most commonly affected are people who have close contact with infected people: health care workers, family members, or people in nearby seats on airplanes or beds in hospitals. However, some people who have developed SARS may not have had such close contact with infected people, and many people who have close contact with infected people do not catch it. The virus is also in stool, and some people appear to have been infected after coming into contact with water supplies contaminated with sewage.
Symptoms and
Diagnosis
Symptoms begin about 2 to 10 days after contact with the virus. The first symptoms resemble those of other more common infections and include fever, headache, chills, and muscle aches. Runny nose and sore throat are unusual. About 3 to 7 days later, a dry cough and difficulty breathing may develop. Most people recover within 1 to 2 weeks. However, about 10 to 20% develop severe difficulty breathing, resulting in insufficient oxygen in the blood. About half of these people need assistance with breathing. However, few people in the United States have had symptoms this severe.
About 10% of infected people die. Death is due to extreme difficulty breathing.
SARS is suspected only if people who may have been exposed to an infected person have a fever plus a cough or difficulty breathing. People may have been exposed if within the previous 10 days, they have traveled to an area where SARS has recently been reported or have had face-to-face contact with a person who may have SARS.
If a doctor suspects SARS, a chest x-ray is usually taken. The doctor may take a swab of secretions from the person's nose and throat to try to identify the virus. A sample of sputum may also be examined. Blood is tested for SARS infection when the infection is first recognized and again 3 weeks later. If the person has difficulty breathing, other blood tests may be needed. Because SARS is a newly identified contagious disease, public health officials are notified of possible cases.
Prevention
and Treatment
Travel advice from the Centers for Disease Control and Prevention (CDC) should be heeded. Wearing a mask is not recommended except for people who are in close contact with someone who may have SARS. People exposed to someone who may have SARS (such as family members, airline personnel, or health care workers) should be alert for symptoms of the infection. If they have no symptoms, they may attend work, school, and other activities as usual. If they develop fever, headache, chills, muscle aches, cough, or difficulty breathing, they should avoid face-to-face contact with other people and see a doctor.
If doctors think a person may have SARS, the person is isolated in a room with a ventilation system that limits the spread of microorganisms in the air. If after 72 hours of isolation, symptoms have not progressed to indicate SARS, the person is usually free to resume normal activities. When health care workers care for a person who may have SARS, they wear masks, goggles, gowns, and gloves.
Doctors may try treating SARS with antiviral drugs, such as oseltamivir and ribavirin, and corticosteroids. However, there is no evidence that these or any other drugs are effective. The virus eventually disappears. People with mild symptoms need no specific treatment. Those with moderate difficulty breathing may need to be given oxygen through plastic nasal prongs or a face mask. Those with severe difficulty breathing may need mechanical ventilation to aid breathing. Research is focused on developing a test for rapid diagnosis, effective treatments, and a preventive vaccine.
Last full review/revision February 2007 by Marguerite Urban, MD
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