At the crossroads: Dr David Heymann says Hong Kong's busy international airport leaves it vulnerable to imported diseases - and to exporting them. He predicts many other places in the world will copy its contact-tracing programme.

The World Health Organisation's Executive Director of Communicable Diseases said Hong Kong could be removed from the list of areas with local recent SARS transmission 20 days after the last case was isolated, noting that the last SARS case was hospitalised on June 3.

Hong Kong is at the crossroads of the world, Dr David Heymann said, making it susceptible to diseases coming in, but also to exporting them. The joint efforts of the Department of Health and the Police in tracing SARS contacts will likely be copied around the globe, he added.

Speaking at a press briefing this morning, Dr Heymann noted that he'd come for Hong Kong for several key reasons.

"Firstly, I came to pay homage to the health workers who worked faithfully during this outbreak to bring it under control," he said.

He also came to see two "unique parts" of the worldwide SARS outbreak that occurred in Hong Kong, the transmission through some type of an environmental factor at Amoy Gardens estates, and the contact tracing that's been done in a joint activity between the Department of Health and the Police through the eSARS and Major Incident Investigation & Disaster Support System systems.

"It's a very unique way of tracing contacts," he said. "It will likely be copied in the future in Hong Kong and imitated throughout the world. It's a very important marriage of databases."

Another key reason for Dr Heymann's visit was to thank Hong Kong scientists for their contribution to the knowledge base of SARS, "on the cause that was first identified here, also on the diagnostics tests which were developed here, and finally on the animal studies which are going on now in collaboration with the Chinese."

He described Hong Kong scientists' role in this outbreak as "very important".

"Had Hong Kong not been as transparent as it had been, the world would be much behind in understanding this outbreak. It's the data which was collected in Hong Kong and also Singapore which has been used by scientists throughout the world to understand so much about this outbreak," he said.

The final reason for his visit was to understand the unique characteristics here in Hong Kong that resulted in such a large outbreak.

He pointed to the population density which is much greater than in other areas where outbreaks have occurred. Certain building design aspects, especially at Amoy Gardens, played a role. Constant population movements between Hong Kong and the Mainland factored in, also.

HK prepares as Guangdong reports encephalitis cluster

Dr Heymann said researchers believed an outbreak of encephalitis in Guangdong Province was Japanese encephalitis. "If that's the case, this is a disease that can be prevented by a vaccine. It's a disease that is transmitted from person to person by insect vector."

In reply to a journalist's query, he said it was important to watch what's happening to make sure that Hong Kong is prepared should it spread here.

"I know the Hong Kong health department is already taking measures," he added.

When asked whether Hong Kong had what it takes to set up a centres for disease control-type facility, Dr Heymann said there was a core group of people here who were well trained to run a CDC.

Setting up such a facility, he said, "would make a critical mass of epidemiologists here to work together on the next outbreak."

Two SARS mysteries remain

There are still two key SARS questions left unanswered:

* Is it seasonal? and

* Where did it come from - and why?

We will know in a year's time whether SARS will flare up again, Dr Heymann said.

Ongoing animal studies may help uncover the source of the coronavirus that caused it, and whether it was spread from one animal to one person who spread it to all others, or whether many animals transmitted it to different people. He warned that we may never learn the original source.

Age plays marked role in fatality

Some interesting statistics regarding SARS' fatality rates have emerged.

For people under 25 years of age, the fatality rate is less than 1%. For those aged 25 to 65, it climbs to 5% to 15%. And for those over age 65, especially with pre-existing medical conditions, it reaches as high as 50%.

Asked why China had a lower fatality rate than Hong Kong, Dr Heymann noted that that was under study, but that people with SARS in China wee generally of a younger age than other SARS-infected places.

Dr Heymann departed this afternoon for Kuala Lumpur for the WHO Global Conference on SARS. Secretary for Health, Welfare & Food Dr Yeoh Eng-kiong will also attend.