Severe Acute Respiratory Syndrome (SARS)


What is SARS?

Severe acute respiratory syndrome (SARS) is a respiratory illness that first infected people in parts of Asia, North America, and Europe in late 2002 and early 2003. SARS is caused by a type of coronavirus, a family of viruses that often cause mild to moderate upper respiratory illness, such as the common cold. This virus is known as SARS-CoV.

Experts believe SARS may have first developed in animals because the virus has been found in civets—a catlike wild animal that is eaten as a delicacy in China—and other animals.1 In the first outbreak 8,096 people became sick with SARS and 774 died.2

How is SARS spread?

Like most respiratory illnesses, SARS is spread mainly through contact with infected saliva or droplets from coughing. You cannot get SARS from brief, casual exposure to an infected person, such as passing someone on the street. In general, you need to have close contact to become infected. Close contact includes living with or caring for a person who has SARS or breathing in air that an infected person exhaled. But under some conditions, SARS has spread within an apartment building and to health care workers. Outbreaks of SARS do not appear to be seasonal.

An infection may develop after:

  • Sharing food or drink with an infected person.
  • Hugging or kissing a person with SARS.
  • Close contact with an infected person.
  • Getting the tiny droplets on your hands by touching contaminated surfaces or objects and then touching your eyes, nose, or mouth.

It is possible SARS can be transmitted in other ways, such as by touching objects that are contaminated with feces from an infected person. This could happen if people do not wash their hands after using the bathroom.

The disease does not appear to spread from a mother to her baby at birth.1

What are the symptoms?

The main symptoms are a fever, a dry cough, shortness of breath, or difficulty breathing. A person with SARS also may experience a headache, muscle aches, a sore throat, fatigue, and diarrhea. Older people may feel generally unwell (malaise) and lose their appetite but not have a fever.1 For some people the symptoms get worse quickly, making hospitalization necessary.

The incubation period—the time from when a person is first exposed to SARS until symptoms appear—is usually 3 to 7 days but may be as long as 10 days. Experts believe a person can spread the illness to others only while he or she has symptoms. As a precaution, though, the U.S. Centers for Disease Control and Prevention (CDC) recommends that people who have SARS stay home, except for doctor visits, until 10 days after their symptoms have gone away.

How is SARS diagnosed?

Your doctor may suspect SARS if you have a fever and you either have traveled to a SARS-affected area or have in the past 10 days been around a person who has SARS.

Your doctor may order several tests to determine the cause of your symptoms. A chest X-ray may be done if you are short of breath or coughing. A blood sample, sputum sample, or nasal swab may be done to detect bacteria or viruses. Your doctor may suspect that you have SARS if tests rule out any other cause for your symptoms, especially if you had contact with someone who has SARS or you traveled to an area experiencing a SARS outbreak. In this case, blood tests may be done to detect substances in your blood (antibodies) that form to fight the SARS virus.

You will need at least two tests for antibodies done on separate days to confirm an infection. You also may have tests to detect the genetic material (RNA) of the SARS virus. RNA testing is not available everywhere.

How is it treated?

Severe cases of SARS often require hospitalization, especially if breathing problems develop. You will be placed in isolation to prevent passing the disease to others. Various medicines—including corticosteroids and the antiviral medicine ribavirin—have been used to treat SARS. But no medicine is known to cure the illness. Doctors continue to search for an effective treatment. One early study showed that the antiviral medicine interferon alfacon-1, taken along with corticosteroids, may help in the treatment of SARS by increasing the amount of oxygen in the blood.3

About one-third (33%) of the people with SARS become ill and then recover.4 The illness gets worse in two-thirds (67%) of the people and is likely to lead to hospitalization.

The risk of dying from SARS depends on a person's age and health. The greatest risk is to people older than 65 and those with chronic illnesses, such as diabetes and heart disease. About 9 out of 10 people infected with SARS recover. About 1 out of 10 people infected with SARS dies.5, 6

How can I avoid being infected with SARS?

The best way to prevent the spread of SARS is to avoid areas where there is an outbreak and avoid contact with people who may be infected. You can also reduce your risk of infection by washing your hands often with soap or alcohol hand cleaners. If an outbreak occurs, try to avoid large public gatherings. The CDC does not recommend wearing face masks in public to prevent infection, although this is a common practice in Asian countries such as Japan.

Researchers are currently trying to develop vaccines to prevent SARS infection. But no vaccines are being tested in humans yet.

Latest Information About SARS

The following health organizations are tracking and studying severe acute respiratory syndrome (SARS). Their Web sites contain the most up-to-date information, including advice for travelers.

  • The World Health Organization (WHO) offers information about the status of the disease around the world, including summaries of research meetings and an archive of articles about the SARS outbreak of 2003. WHO also issues travel recommendations. You can find information at
  • The United States Centers for Disease Control and Prevention (CDC) provides information about the cause of the disease, diagnostic tests, possible treatments, and travel alerts and advisories for affected areas. The Web site also contains recommendations to prevent the spread of infection. You can find information at
  • Health Canada offers information on the government's response to SARS, clinical guidelines, public health and infection control recommendations, and information for travelers. You can find information at
  • British Columbia (BC) Provincial Health Officer offers current information and advice on SARS and provides a link to the British Columbia Centre for Disease Control (BCCDC). You can find information at

Related Information



  1. Peiris JSM, et al. (2003). The severe acute respiratory syndrome. New England Journal of Medicine, 349(25): 2431–2441.
  2. World Health Organization (2003). Summary of Probable SARS Cases With Onset of Illness From 1 November 2002 to 31 July 2003. Available online:
  3. Loutfy MR, et al. (2003). Interferon alfacon-1 plus corticosteroids in severe acute respiratory syndrome: A preliminary study. JAMA, 290(24): 3222–3228.
  4. Hayden FG and Ison MG (2006). Respiratory viral infections. In DC Dale, DD Federman, eds., ACP Medicine, section 7, chap. 25. New York: WebMD.
  5. World Health Organization (2004). Consensus Document on the Epidemiology of Severe Acute Respiratory Syndrome (SARS): Updated Recommendations October 2004. Available online:
  6. Treanor JJ, Hayden FG (2005). Viral infections. In RJ Mason et al., eds., Textbook of Respiratory Medicine, 4th ed., vol. 1, pp. 867–919. Philadelphia: Elsevier Saunders.


Author Maria Essig
Editor Susan Van Houten, RN, BSN, MBA
Associate Editor Denele Ivins
Primary Medical Reviewer Caroline S. Rhoads, MD - Internal Medicine
Specialist Medical Reviewer W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
Last Updated July 13, 2009

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