We thank Mr Kevin Ho Kun Kok for his feedback (Pull out all the stops to fight mosquito breeding, Aug 8).

This year's surge in dengue cases can be attributed to an increase in mosquito population, warmer weather and lowered herd immunity in our population.

The primary carrier of dengue, the Aedes aegypti, thrives in urban settings, breeds in artificial containers and dwells mainly indoors. Keeping premises clean and maintaining them well is an important aspect of mosquito control.

Public areas are cleaned regularly and this is stepped up where there are fallen leaves that can collect water or accumulate in drains and impede water flow.

Residents should alert the National Environment Agency (NEA) or town councils to any choked drains or other areas of concern with cleanliness that could pose a public health risk.

The NEA also studies innovative solutions to complement our existing mosquito control measures.

This includes Project Wolbachia Singapore, which involves the use of male Wolbachia-Aedes mosquitoes to suppress the urban Aedes aegypti population. Results have been promising. However, it remains under research and development.

The NEA is carrying out the Project Wolbachia field study in phases to evaluate the technology systematically.

We are now at Phase 3, which aims to determine if the Aedes aegypti population suppression achieved thus far can be sustained in areas of about 60 and 84 blocks in Tampines and Yishun, respectively - a study site size that is almost four times that carried out in Phase 1 three years ago.

Still, Wolbachia technology is not a silver bullet. As with many other countries in this region where dengue is endemic, comprehensive mosquito surveillance, source eradication of mosquito breeding habitats, and spraying of insecticide where necessary to control the adult mosquito population, continue to be Singapore's key strategies for dengue prevention and control.

Tony Teo

Director, Environmental Public Health Operations

National Environment Agency