Information from the Centers for Disease Control and Prevention

SEVERE ACUTE RESPIRATORY SYNDROME Overview FAQs Prevention Still Worried About Pandemic? All About SARS How SARS Works CDC Info. WHO Info.

What is SARS?

Severe acute respiratory syndrome is a respiratory illness that has recently been reported in Asia, North America, and Europe. For additional information, check the World Health Organization's SARS Web site or visit the CDC's SARS Web site.

What are the symptoms and signs of SARS?

The illness usually begins with a fever (measured temperature greater than 100.4 degrees F [>38.0 degrees C]). The fever is sometimes associated with chills or other symptoms, including headache, general feeling of discomfort, and body aches. Some people also experience mild respiratory symptoms at the outset.

After 2 to 7 days, SARS patients may develop a dry, nonproductive cough that might be accompanied by or progress to the point where insufficient oxygen is getting to the blood. In 10 percent to 20 percent of cases, patients will require mechanical ventilation.

If I were exposed to SARS, how long would it take for me to become sick?

The incubation period for SARS is typically 2 to 7 days; however, isolated reports have suggested an incubation period as long as 10 days. The illness usually begins with a fever (>100.4 degrees F [>38.0 degrees C]) (see signs and symptoms, above).

What medical treatment is recommended for patients with SARS?

CDC currently recommends that patients with SARS receive the same treatment that would be used for any patient with serious community-acquired atypical pneumonia of unknown cause.

Is the use of ribavirin (or other antiviral drugs) effective in the treatment of patients with SARS?

At present, the most efficacious treatment regimen, if any, is unknown. In several locations, therapy has included antivirals such as oseltamivir or ribavirin. Steroids also have been given orally or intravenously to patients in combination with ribavirin and other antimicrobials. In the absence of controlled clinical trials, however, the efficacy of these regimens remains unknown. Early information from laboratory experiments suggests that ribavirin does not inhibit virus growth or cell-to-cell spread of one isolate of the new coronavirus that was tested. Additional laboratory testing of ribavirin and other antiviral drugs is being done to see if an effective treatment can be found.

Spread Of SARS

How is SARS spread?

The primary way that SARS appears to spread is by close person-to-person contact. Most cases of SARS have involved people who cared for or lived with someone with SARS, or had direct contact with infectious material (for example, respiratory secretions) from a person who has SARS. Potential ways in which SARS can be spread include touching the skin of other people or objects that are contaminated with infectious droplets and then touching your eye(s), nose, or mouth. This can happen when someone who is sick with SARS coughs or sneezes droplets onto themselves, other people, or nearby surfaces. It also is possible that SARS can be spread more broadly through the air or by other ways that are currently not known.

How long is a person with SARS infectious to others?

Information to date suggests that people are most likely to be infectious when they have symptoms, such as fever or cough. However, it is not known how long before or after their symptoms begin that patients with SARS might be able to transmit the disease to others.

Who is most at risk of contracting SARS?

In the United States, 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. CDC continues to monitor this situation very closely.

Cause Of SARS

What is the cause of SARS?

Scientists at CDC and other laboratories have detected a previously unrecognized coronavirus in patients with SARS. This new coronavirus is the leading hypothesis for the cause of SARS, however, other viruses are still under investigation as potential causes.

What are coronaviruses?

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. Coronaviruses can survive in the environment for as long as three hours.

What evidence is there to suggest that coronaviruses may be linked with SARS?

CDC scientists isolated a virus from the tissues of two SARS patients and then used several laboratory methods to characterize it. Examination by electron microscopy revealed that the virus has the distinctive shape and appearance of coronaviruses, and genetic analysis suggests that this new virus does belong to the family of coronaviruses but differs from previously identified family members. Tests of serum specimens from people with SARS showed that they appeared to have been recently infected with this virus. Other tests demonstrated that this previously unrecognized coronavirus was present in a variety of clinical specimens (including specimens obtained by nose and throat swab) from other SARS patients with direct or indirect links to the outbreak. These results and other findings reported from laboratories participating in the World Health Organization (WHO) network provide growing evidence in support of the hypothesis that this new coronavirus is the cause of SARS. Additional studies of the link between this coronavirus and SARS are under way.

If coronaviruses usually cause mild illness in humans, how could this new coronavirus be responsible for a potentially life-threatening disease such as SARS?

There is not enough information about the new virus to determine the full range of illness that it might cause. Coronaviruses have occasionally been linked to pneumonia in humans, especially people with weakened immune systems. The viruses can also cause severe disease in animals, including cats, dogs, pigs, mice, and birds.

Has new information about coronavirus changed the recommendations for medical treatment for patients with SARS?

The possibility that coronavirus is the cause of SARS has not changed treatment recommendations. The new coronavirus is being tested against various antiviral drugs to see if an effective treatment can be found.

Is there a test for SARS?

No "test" is available yet for SARS; however, the CDC, in collaboration with WHO and other laboratories, has developed two research tests that appear to be very promising in detecting antibodies to the new coronavirus. CDC is working to refine and share this testing capability as soon as possible with laboratories across the United States and internationally.

What about reports from other laboratories suggesting that the cause of SARS may be a paramyxovirus?

Researchers from several laboratories participating in the WHO network have reported the identification of a paramyxovirus in clinical specimens from SARS patients. These laboratories are still investigating the possibility that a paramyxovirus is a cause of SARS.

Is there any reason to think SARS is or is not related to terrorism?

Information currently available about SARS indicates that people who appear to be most at risk are either health-care workers taking care of sick people or family members or household contacts of those who are infected with SARS. That pattern of transmission is what would typically be expected in a contagious respiratory or flulike illness.