David Heymann, the World Health Organization (WHO)'s Executive Director for Communicable Diseases told reporters at a news conference Monday.

"Animal studies, depending on how much interest is put into these, could be done within a year. But it will be very difficult to say what the risk factors are. Because that would take some very detailed case control studies.

"We believe it came from some type of animal in nature. We don't know if it came from only one type into human and then that initial human was responsible for all the different human outbreaks. If that's the case, it may be that the genetic analysis can tell us that. It was not from eating the meat. It was probably from the butchering process, the blood that would be involved," Heymann said.

However, for the time being the vital medical answers the WHO is seeking is the seasonality for the disease and whether rebounds are likely.

"The key thing we want to know now is this a season disease? Will it re-occur in the season where the virus remain either in people who are asymptomatic or in the environment and begins its transmission again when the season has changed. The seasonality will require one-year of intensive surveillance from now.... Next year this time, we'll be able to give a better idea about the possibility of seasonality.

"And the second is, if it is not seasonal, if its transmission has been interrupted worldwide, and the virus is out of human population, what are the risk factors that have led the past and that could lead again the future? What are the animal reservoirs? What are the reasons that have left the animal reservoir and enter the human population?," he said.

Amidst all the unknown factors though, Heymann has praised the Hong Kong government and its public hospital system for taking all the clinical management practices and preventive measure necessary to contain the spread of the disease. He particularly praised the hospitals for remaining open to rescue patients during the height of the outbreak.

"Hospitals were never meant to be closed. Hospitals must take care of people. What's important is that the area where the infectious disease patients are kept or isolated appropriately, and that is happening in Hong Kong," he said.

Commenting on Hong Kong's ability to set up some kind of a center for disease control (CDC), Heymann remarked, "Certainly there is a core of people who here are very well-trained to run a CDC in Hong Kong. We've seen excellent outbreak containment using basic epidemiological principles, identification of cases, isolation of cases, control, contact tracing and quarantine of contacts," he said.

(Xinhua News Agency June 17, 2003)