TORONTO: With reports that SARS (severe acute respiratory syndrome) can survive for up to 24 hours on inanimate surfaces, turning any object into a potential transmission source, it looks like the virus might indeed be the global pandemic suggested by health experts. But what exactly does that mean?

David Heymann, executive director of the communicable diseases section at the World Health Organization (WHO), says SARS could pose a more serious global health threat than any other new disease in the past 20 years, with the sole exception of HIV, which causes AIDS.

The epidemic had infected 4,000 people and killed at least 228 in 25 countries as of April 22, according to WHO. Roughly 90 per cent of the cases were in China and Hong Kong and overall numbers were expected to continue to rise. Thousands of people are currently in quarantine worldwide, and that number could grow dramatically as China struggles with the disease.

In 1918 a new influenza virus killed at least 20 million people before it disappeared. While the worst human epidemic on record, that flu virus was not particularly lethal, killing only three to five per cent of those infected. The SARS death rate is estimated at four per cent. The Ebola virus is much more deadly, killing half its victims, while HIV kills virtually everyone infected.

In an unprecedented worldwide collaboration, scientists earlier this month identified SARS as a new Coronavirus. “It took three years to find the cause of AIDS and HIV,” said WHO spokesman Dick Thompson. “It took eight days to find the cause of this disease.”

On the other hand, SARS is operating in a much more fast- paced, interlinked world than that which spawned HIV, Heymann pointed out. Its apparent incubation period of two to 10 days is long enough for infected people who are asymptomatic to travel “from one city in the world to any other city having an international airport”.

SARS can also be spread via droplets, excreted when we sneeze or cough, and the initial symptoms — dry cough, headache, fever — are non-specific and common, he noted.

The global cost of the disease is already estimated at $30 billion, Heymann said.

The family of Coronaviruses, so named because of the distinctive crown that encircles the viral particle, cause 20 to 30 per cent of common colds in humans as well as diseases in many domestic animals, including pigs, cats, dogs, cattle, chickens, turkeys, rats and mice.

Viruses are simply small packages of genetic material — DNA or RNA — plus a few enzymes surrounded by a protective coat of protein or fat. On their own, they are relatively inert — unable to move, grow or reproduce.

Controlling a highly contagious virus is much more difficult without a diagnostic test. One that would identify SARS in a person’s blood or saliva could be just weeks away after Canada’s Michael Smith Genome Sciences Centre in Vancouver recently announced the virus’s genetic sequence.

Drug companies “are madly testing all of their drugs that work against AIDS and hepatitis C right now to see if they work on the Coronavirus,” said Kathryn Holmes, a Coronavirus expert at the University of Colorado Health Sciences Center in Denver.

Julie Gerberding, Director US Centres for Disease Control, says if civilization is lucky diagnostic tests and treatment will be found to curtail the epidemic. A seasonal pattern will evolve, allowing scientists to contain infections within regions, and the infection rate will slow.—Dawn/InterPress News Service.