Definition of Severe acute respiratory syndrome (SARS):

Severe acute respiratory syndrome (SARS) is a serious form of pneumonia. It is caused by a virus that was first identified in 2003. Infection with the SARS virus causes acute respiratory distress (severe breathing difficulty) and sometimes death.

SARS is a dramatic example of how quickly world travel can spread a disease. It is also an example of how quickly a connected health system can respond to a new health threat.

Background Information:

World Health Organization (WHO) physician Dr. Carlo Urbani identified SARS as a new disease in 2003. He diagnosed it in a 48-year-old businessman who had traveled from the Guangdong province of China, through Hong Kong, to Hanoi, Vietnam. The businessman and the doctor who first diagnosed SARS both died from the illness.

In the meantime, SARS was spreading. Quickly it infected thousands of people around the world, including people in Asia, Australia, Europe, Africa, and North and South America. Schools closed throughout Hong Kong and Singapore. National economies were affected.

The WHO identified SARS as a global health threat, and issued a travel advisory. WHO updates closely tracked the spread of SARS. It wasn't clear whether SARS would become a global pandemic.

The fast global public health response helped to stem the spread of the virus. By June 2003, the number of new cases was down enough that on June 7, the WHO stopped its daily reports. But even though the number of new cases dwindled and travel advisories began to be lifted, every new case had the potential to spark another outbreak.

SARS appears to be here to stay. It has changed the way that the world responds to infectious diseases during a time of widespread international travel. The 2003 outbreak had an estimated 8,000 cases and 750 deaths.

Causes, incidence, and risk factors:

SARS is caused by a member of the coronavirus family of viruses (the same family that can cause the common cold). It is believed the 2003 epidemic started when the virus spread from small mammals in China.

When someone with SARS coughs or sneezes, infected droplets spray into the air. You can catch the SARS virus if you breathe in or touch these particles. The SARS virus may live on hands, tissues, and other surfaces for up to 6 hours in these droplets and up to 3 hours after the droplets have dried.

While the spread of droplets through close contact caused most of the early SARS cases, SARS might also spread by hands and other objects the droplets has touched. Airborne transmission is a real possibility in some cases. Live virus has even been found in the stool of people with SARS, where it has been shown to live for up to 4 days. The virus may be able to live for months or years when the temperature is below freezing.

With other coronaviruses, becoming infected and then getting sick again (re-infection) is common. This may also be the case with SARS.

Symptoms usually occur about 2 to 10 days after coming in contact with the virus. There have been some cases where the illness started sooner or later after first contact. People with active symptoms of illness are contagious, but it is not known for how long a person may be contagious before or after symptoms appear.