ONE of virologist Lynette Oon's most vivid memories of Sars was the sight of "a huge mountain of stool samples" in the laboratory at the peak of the 2003 epidemic.

Besides being present in respiratory secretions, the virus, which affects the gastro-intestinal system, is also found in human waste.

Taking stool samples was the safest way of testing for the illness, as obtaining samples from patients' respiratory secretions put health-care workers at greater risk of contamination.

Dr Oon and a team of medical virologists were responsible for tracking down the mysterious virus that had infected a patient in the first week of March that year.

At that time, no one - not even the international community - knew what they were dealing with.

The 45-year-old remembers her then superior, Dr Ling Ai Ee, being on the phone most evenings comparing results with various laboratories around the world.

"The first part of the outbreak was trying to find out what the virus was, in collaboration with international colleagues. The second part was really to develop a rapid test," said Dr Oon, a senior consultant at the pathology department of Singapore General Hospital (SGH).

At the peak of the crisis, the virology laboratory - the main one here at the time - dealt with about 200 samples a day.

This was on top of the average of 20 that the facility ordinarily deals with on a daily basis.

"We had a huge problem on our hands," said Dr Oon. "We could not cope with the testing."

Local collaborations then kicked in, with other hospitals and laboratories sharing the work.

Today, the SGH laboratory has doubled in size and other hospital laboratories have also developed their own capabilities to do rapid viral molecular tests.

The experience also prepared them for the H1N1 outbreak in 2009.

"Because of Sars, we were much calmer when we faced it," Dr Oon said.

MELISSA PANG