Scientists may have killed a dengue outbreak in Singapore

Straits Times 29 Jul 09;

A DENGUE outbreak here may have been stopped in its tracks by a team of scientists at the Environmental Health Institute.

In March, the scientists, studying common strains of the virus here, discovered the resurfacing of a third, less common type in Little India and Geylang. They alerted the National Environment Agency (NEA), which stepped up its infection control measures and manpower to rid these areas of mosquito breeding.

Yesterday, the institute's key findings on dengue and chikungunya were presented by its head, Dr Ng Lee Ching, at an EU-South-east Asia meeting on vector-borne diseases, organised by the Singapore Immunology Network under the Agency for Science, Technology and Research.

For instance, there are four strains or sterotypes of dengue. A switch in predominance from one strain to another is associated with outbreaks, as people have lower immunity to a new strain.

Researchers also found that the chikungunya virus can replicate in mosquitoes and be ready to infect humans within just three days, compared to seven to 14 days for the dengue virus.

That's why chikungunya can spread so fast - just as it did last year, when the first local infections struck here. Since the start of last year, there have been 803 local cases and 214 cases imported from elsewhere in Asia.

Researchers are now also able to conduct genetic 'paternity tests' to discover which countries the virus came from, said Dr Ng.

The institute is still studying the current malaria outbreak, she added.

The disease, which resurfaced here with perhaps the largest local cluster in almost three decades, is transmitted by the Anopheles mosquito.

'Today's Anopheles population might be very different from the past; it may have evolved and changed, and we know less about that change,' Dr Ng said.

But one difficulty of studying Anopheles mosquitoes is getting the insects, which are outdoor breeders, to reproduce in the lab.

'You can't force them to mate - they're very shy,' Dr Ng quipped.

At the same two-day conference, which ended yesterday, Imperial College London rector Sir Roy Anderson announced that the British university was in early talks with local varsities and research institutes to start a programme or school for global and public health.