Severe acute respiratory syndrome, or SARS, is a contagious and potentially fatal respiratory illness.
It first appeared in China in November 2002 and was identified in February 2003.
SARS spread to over 24 countries before it was contained. Since May 2004, no new cases have been reported.
From November 2002 to July 2003, there were 8,098 cases worldwide and 774 deaths.
The United States (U.S.) saw eight laboratory-confirmed cases and no fatalities. All eight people had traveled to areas affected by SARS.
Strong levels of global cooperation ensured that the threat of SARS was dealt with swiftly, and the spread of the disease was effectively contained.
What is SARS?
SARS is extremely contagious, and many wore face masks during the last outbreak in 2002.
The SARS coronavirus (SARS-CoV) causes SARS. A coronavirus is a common form of virus that typically causes upper-respiratory tract illnesses. The common cold results from a kind of coronavirus.
Six different kinds of coronavirus are known to infect humans. Four of these are common, and most people will experience at least one of them at some time in their life.
The two other types cause SARS and Middle East Respiratory Syndrome (MERS). These are less common but far more deadly.
Before SARS appeared, coronaviruses had not been particularly dangerous to humans, but they had been known to cause severe diseases in animals.
As a result, scientists first thought that animals transmitted SARS-CoV to humans. They now believe that an animal virus changed into a new, more deadly strain.
SARS was the first coronavirus to present severe symptoms in humans.
Diseases that pass from animals to humans are called zoonotic diseases. They are relatively rare.
The main concern when they first emerge is that they are new strains and also new to humans, so the human body does not yet have immunity.
It is often impossible to predict what may happen. In the case of SARS, animals may have been a host for the virus.
In 2013, scientists discovered that two new coronaviruses found in Chinese horseshoe bats are a close relative of the SARS-coronavirus.
A report published in 2014 suggested that over 320,000 mammal viruses have not yet been discovered.
Symptoms normally appear within 3 to 5 days after exposure to the SARS virus, but they can develop after 2 to 7 days. During the incubation period, before symptoms appear, the disease is not contagious.