Severe acute respiratory syndrome (SARS)

SARS is caused by the SARS coronavirus (SARS CoV). There are a large number of coronaviruses linked to infections in humans and animals.
There are two recognised human coronaviruses that cause mild respiratory infections, such as the common cold . This type of virus can also include strains that cause more severe illnesses, such as SARS.
SARS originated in the Guangdong province of southern China in 2002. The infection quickly spread to other countries (a pandemic), and resulted in more than 8,000 cases and 774 deaths before the virus was eventually brought under control.

Symptoms of SARS

SARS has flu-like symptoms that usually begin 2-10 days after infection. They include:

• high temperature (fever) of 38ºC (100.4ºF) or above
• fatigue (extreme tiredness)
• headaches
• chills
• muscle pain
• loss of appetite
• diarrhoea

Between 3-7 days after the start of these symptoms, the infection will begin to affect your respiratory system (lungs and airways). This will lead to additional symptoms such as:

• a dry cough
• breathing difficulties
• an increasing lack of oxygen in the blood, which can be fatal in the most severe cases

The SARS pandemic

It is thought a strain of the coronavirus usually only found in small mammals mutated, enabling it to infect humans.
The SARS infection quickly spread from China to other Asian countries. There were also a small number of cases in several other countries, including four in the UK, plus a significant outbreak in Toronto, Canada.
The SARS pandemic was eventually brought under control in July 2003, following a policy of isolating people suspected of having the condition, and screening all passengers travelling by air from affected countries for signs of the infection.
During the period of infection, there were 8,098 reported cases of SARS and 774 deaths. This means that the virus killed about 1 in 10 people who were infected. People over 65 years of age were particularly at risk, with over half dying from the infection in this age group.
In 2004, there was another small SARS outbreak, linked to a medical laboratory in China. It was thought to have been the result of someone coming into direct contact with a sample of the virus, rather than being caused by animal-to-human or human-to-human transmission.

How SARS is spread

SARS is an airborne virus, which means it is spread in a similar way to flu and the common cold
The SARS virus is spread in small droplets of saliva coughed or sneezed into the air by an infected person. Infection can occur if someone else breathes in the droplets.
SARS can also be spread indirectly if an infected person touches surfaces, such as door handles, with unwashed hands. Someone who touches the surface may also become infected.
The SARS virus may also be spread through an infected person's faeces (stools). For example, if they do not wash their hands properly after going to the toilet, they may be able to pass the infection on to others.
Evidence from the SARS pandemic in 2002/03 showed that people living with or caring for someone with a known SARS infection were most at risk of developing the infection themselves.

Treatment for SARS

There is currently no cure for SARS, but research to find a vaccine is ongoing.
A person suspected of having SARS should be admitted to hospital immediately and kept in isolation under close observation.
Treatment is mainly supportive and may include:

• assisting with breathing using a ventilator to deliver oxygen
• antibiotics to treat bacteria that cause pneumonia
• antiviral medications
• high doses of steroids to reduce swelling in the lungs

There is little in the way of scientific evidence to show that these treatments are very effective. The antiviral medication, ribavirin, is known to be ineffective at treating SARS.

Prevention advice

You should avoid travelling to areas of the world where there is an uncontrolled SARS outbreak.
To reduce your risk of becoming infected, avoid direct contact with people with SARS (until at least 10 days after their symptoms have gone).
To avoid spreading the infection, it is important to follow the prevention advice outlined below:

• wash your hands thoroughly using an alcohol-based hand detergent
• cover your mouth and nose when you sneeze or cough
• avoid sharing food, drink and utensils
• regularly clean surfaces with disinfectant

In some situations, it may be appropriate to wear gloves, masks and goggles to help prevent the spread of SARS.

Future SARS outbreaks

Although the threat of SARS to public health seems to have passed, international health officials continue to remain vigilant. The World Health Organization (WHO) monitors countries throughout the world for any unusual disease activity.
Therefore, if another SARS outbreak were to occur, it should be possible to limit the spread of infection using the same measures implemented during the 2002/03 pandemic (see above).