Frequently Asked Questions About SARS
September 29, 2003, 3:00 PM ET - CDC

THE DISEASE

What is SARS?
Severe acute respiratory syndrome (SARS) is a viral respiratory illness that was first reported in Asia in February 2003. In early March, the World Health Organization (WHO) issued a global alert about SARS. Over the next few months, the illness spread to more than two dozen countries in North America, South America, Europe, and Asia. By late July, however, no new cases were being reported and the illness was considered contained. According to WHO, 8,098 people worldwide became sick with SARS during this outbreak; of these, 774 died. For more information, check the WHO SARS Web site or visit other pages on CDC's SARS Web site.

What are the symptoms and signs of SARS?
The illness usually begins with a high fever (measured temperature greater than 100.4°F [>38.0°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. Diarrhea is seen in approximately 10 percent to 20 percent of patients.

After 2 to 7 days, SARS patients may develop a dry, nonproductive cough that might be accompanied by or progress to a condition (hypoxia) in which insufficient oxygen is getting to the blood. In 10 percent to 20 percent of cases, patients require mechanical ventilation. Most patients develop pneumonia. For more information, see the MMWR dispatch that describes the clinical features of SARS.

What is the cause of SARS?
SARS is caused by a previously unrecognized coronavirus, called SARS-associated coronavirus (SARS-CoV). It is possible that other infectious agents might have a role in some cases of SARS. For more information about the SARS coronavirus, click here.

How is SARS spread?
The primary way that SARS appears to spread is by close person-to-person contact. The virus that causes SARS is thought to be transmitted most readily by respiratory droplets (droplet spread) produced when an infected person coughs or sneezes. Droplet spread can happen when droplets from the cough or sneeze of an infected person are propelled a short distance (generally up to 3 feet) through the air and deposited on the mucous membranes of the mouth, nose, or eyes of persons who are nearby. The virus also can spread when a person touches a surface or object contaminated with infectious droplets and then touches his or her mouth, nose, or eye(s). In addition, it is possible that SARS-CoV might be spread more broadly through the air (airborne spread) or by other ways that are not now known.

What does “close contact” mean in the context of the SARS outbreak?
Close contact is defined in the CDC SARS case definition as having cared for or lived with a person known to have SARS or having a high likelihood of direct contact with respiratory secretions and/or body fluids of a patient known to have SARS. Examples include kissing or embracing, sharing eating or drinking utensils, close conversation (within 3 feet), physical examination, and any other direct physical contact between people. Close contact does not include activities such as walking by a person or sitting across a waiting room or office for a brief time.

If I were exposed to SARS, how long would it take for me to become sick?
The time between exposure to the SARS virus and onset of symptoms is called the “incubation period.” The incubation period for SARS is typically 2 to 7 days, although in some cases it may be as long as 10 days.

How long is a person with SARS infectious to others?
Available information suggests that people with SARS are most likely to be infectious only when they have symptoms, such as fever or cough. However, as a precaution against spreading the disease, CDC recommends that people with SARS limit their interactions outside the home (for example, by not going to work or to school) until 10 days after their symptoms have gone away. Patients are most infectious during the second week of illness.

Do some people who recover from SARS become sick again or relapse?
At this time we do not have a full understanding of the natural course of illness in persons infected with SARS-CoV. It will be important to learn what factors might influence illness progression and recovery. Such factors could be related to the virus itself, how the body's immune system reacts to the virus, how infection with the virus is treated, or other possibilities. CDC and other scientists are trying to learn the answers to these important questions.

What medical treatment is recommended for patients with SARS?
CDC recommends that patients with SARS receive the same treatment that would be used for any patient with serious community-acquired atypical pneumonia. SARS-CoV is being tested against various antiviral drugs to see if an effective treatment can be found.

THE SARS OUTBREAK

What is the status of the SARS outbreak?
SARS was first reported in Asia in February 2003, and over the next few months the illness spread to more than two dozen countries in North America, South America, Europe, and Asia. By late July, no new cases were being reported and the global outbreak was declared over by WHO. For more information, check the WHO SARS Web site or visit other pages on CDC's SARS Web site.

How many people contracted SARS worldwide during the outbreak? How many people died of SARS?
According to WHO, 8,098 people worldwide became sick with SARS during the course of this outbreak; of these, 774 died. Visit WHO's SARS page for more information on the numbers of SARS cases and deaths.

How widespread was the SARS outbreak in the United States?
Through July 2003, a total of 192 SARS cases had been reported in the United States, including 159 suspect and 33 probable cases; of the 33 probable cases, only 8 had laboratory evidence of SARS-CoV infection. No SARS-related deaths occurred in the United States. SARS cases reported in the United States occurred primarily among people who traveled to SARS-affected areas; a small number of other people became ill after being in close contact with (that is, having cared for or lived with) a SARS patient while in the United States. There was no evidence that SARS spread more widely in the community in the United States. For information about the number of cases reported in each state, see CDC’s summary of SARS cases.

What is the difference between a “probable” SARS case and a “suspect” SARS case?
As defined in CDC’s SARS case definition, suspect SARS cases have fever, respiratory illness, and recent travel to an affected area with community transmission of SARS and/or contact with a suspect SARS patient. Probable cases meet the criteria for a suspect case and also have evidence (e.g., chest X-ray) of pneumonia or respiratory distress syndrome.

What was done to contain the SARS outbreak in the United States?
To minimize the risk for SARS among U.S. residents, the public health system took careful and thorough precautions to prevent the spread of SARS. People who were suspected of having SARS were isolated from others and received care. People arriving from affected parts of the world (who might have been exposed to SARS) received information about SARS and instructions on what they should do if they became ill. SARS patients and their contacts were monitored to help prevent spread of the disease. For more information, see the various guidance documents on CDC’s SARS Web site.

What did CDC do to combat this health threat?
CDC worked closely with WHO and other partners in a global effort to address the SARS outbreak. For its part, CDC took the following actions:

• Activated its Emergency Operations Center to provide round-the-clock coordination and response.
• Committed more than 800 medical experts and support staff to work on the SARS response.
• Deployed medical officers, epidemiologists, and other specialists to assist with on-site investigations around the world.
• Provided assistance to state and local health departments in investigating possible cases of SARS in the United States.
• Conducted extensive laboratory testing of clinical specimens from SARS patients to identify the cause of the disease.
• Initiated a system for distributing health alert notices to travelers who may have been exposed to cases of SARS.

In addition, CDC is continuing to work with federal, state, and local health departments and other professional organizations to plan for a rapid recognition and response should SARS re-emerge.

If there is another outbreak of SARS, how can I protect myself?
If SARS were to re-emerge, there are some common-sense precautions that you can take that apply to many infectious diseases. The most important is frequent hand washing with soap and water or use of alcohol-based hand rubs (see Guideline for Hand Hygiene in Health-Care Settings). You also should avoid touching your eyes, nose, and mouth with unclean hands and encourage people around you to cover their nose and mouth with a tissue when coughing or sneezing.

SARS-ASSOCIATED CORONAVIRUS

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.

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 also can cause severe disease in animals, including cats, dogs, pigs, mice, and birds.

How long can SARS-CoV survive in the environment?
Preliminary studies in some research laboratories suggest that the virus may survive in the environment for several days. The length of time that the virus survives likely depends on a number of factors. These factors could include the type of material or body fluid containing the virus and various environmental conditions such as temperature or humidity. Researchers at CDC and other institutions are designing standardized experiments to measure how long SARS-CoV can survive in situations that simulate natural environmental conditions.

Are there disinfectants available that can inactivate (kill) SARS-CoV?
Right now, there are no disinfectant products registered by the U.S. Environmental Protection Agency for use on environmental surfaces that are specifically listed as having the ability to kill SARS-CoV. However, related viruses that have similar physical and biochemical properties can be killed with bleach, ammonia or alcohol, or cleaning agents containing any of these disinfectants. Cleaning agents should be used according to the manufacturer's instructions.

LABORATORY TESTING

Is there a laboratory test for SARS?
Yes, several laboratory tests can be used to detect SARS-CoV. A reverse transcription polymerase chain reaction (RT-PCR) test can detect SARS-CoV in clinical specimens, including blood, stool, and nasal secretions. Serologic testing also can be performed to detect SARS-CoV antibodies produced after infection. Finally, viral culture has been used to detect SARS-CoV.

What is a PCR test?
PCR (or polymerase chain reaction) is a laboratory method for detecting the genetic material of an infectious disease agent in specimens from patients. This type of testing has become an essential tool for detecting infectious disease agents.

What does serologic testing involve?
A serologic test is a laboratory method for detecting the presence and/or level of antibodies to an infectious agent in serum from a person. Antibodies are substances made by the body's immune system to fight a specific infection.