[Judith Anne]

If the SARS virus escaped from a lab, does this mean that there are no naturally occurring cases this year?

[Mother Abigail]

I believe not, however this is now the 3rd incident of SARS transmission within a laboratory working on SARS research.

The first 2 occurred in Singapore and Taiwan since the 2003 outbreak.

It seems as though laboratory exposure is a higher risk factor than the possible zoonotic exposure. -

[Mother Abigail]

RE: Naturally occurring cases

Jan 04, 2004

Rats may prove to be the missing link in a suspected case of SARS (severe acute respiratory syndrome) first reported in Guangzhou, capital city of South China's Guangdong Province.

A mutated strain of the deadly virus was diagnosed on a 32-year-old freelance television producer, making him the first suspected SARS patient on the mainland since last May.

However, health officials and top experts reached by China Daily yesterday cautioned that more laboratory tests must be done before any confirmation can be made.

New details surfaced when local Guangzhou media reported the patient had set traps for rats that had invaded his apartment before he showed SARS symptoms. Laboratory tests have shown that some of the rats caught in his apartment also tested positive for SARS.

However, this does not necessarily mean that the rats are the definitive source of the new strain of coronavirus, Liu Qiyong, an expert on epidemics from the Chinese Centre for Diseases Control and Prevention (CDC), said yesterday.

The result may have been caused by some other strain of coronavirus carried by the rats, since there is a slight difference from the kind that caused the SARS outbreak in human beings last spring, Liu said. In fact, other strains have been found in rats, as well as in other animals long before the new case emerged.