SARS: Health workers fear
newer infection routes

Doctors still haven't pinned down exactly how a deadly flu-like virus is spreading and more cases are pointing to possible new ways it is using to pass from one victim to another.

A top Hong Kong health official on Tuesday said cockroaches might have spread the virus that causes Severe Acute Respiratory Syndrome (SARS) in an apartment complex in the city, leading to nearly 300 infections in a matter of days.

If proved true, it would represent an alarming development in the swiftly spreading epidemic in Hong Kong, a city of nearly seven million people filled with densely populated apartment buildings.

Health officials are also looking at the possibility that SARS can be spread by a latter-day version of Typhoid Mary, a cook in early 20th century America who spread typhoid fever without showing the symptoms herself.

SARS has killed more than 100 people and infected 2,750 worldwide since it surfaced in southern China late last year.

The World Health Organisation's infectious diseases chief said at the weekend he feared the SARS virus could be carried by people without symptoms.

"If there are people who have the virus and don't show symptoms, we are lost, because that would mean it had spread throughout the world, as it is easily contracted," David Heymann said in an interview with Spain's El Pais daily.

"That was how AIDS was transmitted before it was discovered. We still don't know if this is the case, that's why we need a test," he added.

In an April 7 update published on their web site, the WHO said that SARS diagnostic tests developed so far were problematic.

It said a test available for detection of SARS virus genetic material was useful in the early stages of infection.

But it produced 'many false-negatives, meaning that many persons who actually carry the virus may not be detected -- creating a dangerous sense of false security'.

This was the case with Fung Hong, the chief executive of a group of Hong Kong hospitals, who was confirmed with SARS early this week after originally testing negative for the virus.

This leaves open the possibility of more such cases and possible wrong diagnoses of patients showing some but not all the common symptoms, such as chills, high fever, body aches and breathing difficulties.

While the WHO has said the virus, new to science, has been isolated, little is known about it and there is no known cure.

"We don't know all the details of how the virus spreads. There's a limit to how much a country can prepare," said Dr David Bell on Tuesday. Bell is a Manila-based member of the WHO team dealing with SARS in East Asia.

SARS is highly contagious and doctors say it can easily be spread to others in close contact with ill patients.

Touching door handles, lift buttons or water taps that have been contaminated by droplets from an infected persons' coughs or sneezes is another way to pass on the virus.

Bell said it was possible -- but not yet proven -- that the occasional person could be a carrier of SARS without suffering severe symptoms.

"It's quite likely it occurs but it's probably very unusual. There's no evidence. If that were common, it would be spreading right through the community like influenza or something like that -- and the fact is it isn't," he added.

"All of the large outbreaks have been traced back to a person who had symptoms."

Singapore, which has imposed perhaps the most rigorous controls of any government in an affected area, now says SARS has spread to staff at five of the nation's six big hospitals.

After a lull in new cases, the island republic reported two deaths and seven new cases on Monday, its highest such numbers in two weeks. Eight people have died of SARS in Singapore.

Hong Kong, which has nearly 900 cases and fears many more in the coming weeks, is also trying to contain a new outbreak in one hospital and possibly a second.

A local councillor said on Tuesday the virus had spread to at least 14 housing estates in a densely populated new town that is home to hundreds of thousands of people.

But it is the rapid spread of SARS among residents of the Amoy Gardens apartment complex in Hong Kong that has baffled and alarmed health officials and led to theories the virus could be airborne, spread through the water supply -- or even by cockroaches.

(Additional reporting by John O'Callaghan in Manila)

Reuters