A deadly pneumonia-like virus spreading across the world has killed 62 people and infected more than 1,700 others, mainly in Asia.

Below is a list of the most frequently asked questions about the disease and answers from health experts.

Following are facts about the Severe Acute Respiratory Syndrome, a type of atypical pneumonia, and what medical experts are saying about it:

WHAT IS IT?

- Scientists say SARS is caused by a new virus from the family of coronaviruses, which also causes the common cold.

The US Centers for Disease Control and Prevention say evidence is mounting that the virus is the primary causative agent, but experts say much laboratory work still needs to be done to pinpoint its exact characteristics. Development of a vaccine will take years.

The WHO says the disease originated in China's southern province of Guangdong, before spreading to Hong Kong, where it was then carried to Vietnam, Singapore, Canada. Cases have later surfaced in other places including the United States, France, Britain, Taiwan and Germany.

Hong Kong and WHO scientists say the strain likely originated from animals although it does not appear anything like any known human or animal viruses.

Health experts in Hong Kong have ruled out any association with influenza A and B viruses, and also the H5N1 bird-flu virus which jumped the species barrier and killed six people in the territory in 1997, and a man in February.

SARS is a type of atypical pneumonia, which is usually caused by viruses, such as influenza viruses, adenovirus and other respiratory viruses, according to Hong Kong health officials.

Atypical pneumonia can also be caused by organisms such as Legionella bacteria.

WHO says there is no indication SARS is linked to bioterrorism.

WHAT ARE THE SYMPTOMS?

- The World Health Organization says the main symptoms of SARS are high fever, dry cough, shortness of breath or breathing difficulties. Changes in chest X-rays, which are indicative of pneumonia, also occur.

SARS may be associated with other symptoms, including chills, headache, muscular stiffness, loss of appetite, malaise, confusion, rash and diarrhoea.

Health experts say the disease has an incubation period of between 2-7 days, with 3-5 days being more common, before victims start showing flu-like symptoms.

HOW DANGEROUS IS IT?

- The mortality rate appears to be between 3 to 5 percent. In Hong Kong, at least, those who are infected invariably develop severe pneumonia, which can cause numerous complications. Conditions of victims deteriorate very quickly, in as little as five days.

HOW ARE PATIENTS TREATED?

- There is currently no specific cure for the disease. But doctors worldwide have been treating it with ribavirin + an anti-viral drug + and steroids. Doctors say if treated early most patients without other serious illnesses can recover.

A top Hong Kong doctor told Reuters in an exclusive interview late on Monday that some of the worst affected patients in Hong Kong were being successfully treated using antibodies in serum from recovered patients.

The presence of antibodies means those who have recovered likely would have developed some level of immunity against the virus in the future. But some experts have not ruled out the possibility that a person could be infected again and again.

HOW DOES IT SPREAD?

- WHO and Hong Kong experts say the virus spreads through droplets by sneezing or coughing and such direct infection can usually occur within a radius of about three feet (one metre).

The virus can also spread indirectly as it can survive outside of the human body for three to six hours. Contact with any object that is tainted by droplets containing the virus, for example, a contaminated phone, could lead to infection if a person then touches their eyes, nose or mouth.

Health experts have not ruled out that it could be airborne, which dramatically aises the contagious nature of the virus and would make it far harder to contain.

HOW FAST DOES IT SPREAD?

- WHO says SARS appears to be less infectious than influenza, and is not highly contagious when protective measures are used. Hong Kong's health chief has said the virus is highly infectious, though some other medical experts are more cautious about that possibility. Hong Kong officials say it can be killed by a solution of water and common household bleach.

HOW DOES THE VIRUS TRAVEL GLOBALLY?

- WHO says the speed of international travel creates a risk that cases can spread rapidly around the world.

When an infected person travels, they can spread the virus to other passengers on their flight and also to people at their destination. Authorities around Asia are hunting for passengers who were on about half a dozen flights as they fear that these passengers have been exposed.

WHO IS MOST LIKELY TO BE INFECTED?

- Hong Kong experts say the virus is highly concentrated in discharges such as mucous or phlegm when the victim is very sick and needing hospitalisation. Therefore, the virus has tended to spread primarily to health care professionals treating victims or close family members of victims.

HOW SHOULD INFECTED PATIENTS BE MANAGED?

- WHO says patients should be placed in an isolation unit. Health care workers and visitors should wear efficient filter masks, goggles, aprons, head covers, and gloves when in close contact with the patient.

IS IT SAFE TO TRAVEL?

- WHO has not recommended restricting travel to any destination in the world. However, all travellers should be aware of the main symptoms and signs of SARS. People who have these symptoms and have been in close contact with a person who has been diagnosed with SARS, or have a recent history of travel to areas where cases of SARS have been spreading, should seek medical attention and inform health care staff of recent travel.

Travellers who develop these symptoms are advised not to undertake further travel until fully recovered.

Editor: Wings