Forum: Dengue control measures have significantly reduced transmissions

A pest-control officer carrying out misting in the premises of Eastvale Condominium on Aug 5, 2019.
A pest-control officer carrying out misting in the premises of Eastvale Condominium on Aug 5, 2019.PHOTO: ST FILE

We thank Mr Teo Yew Cheng for his feedback (Fight against coronavirus laudable, but what about dengue effort?, Feb 24).

Dengue is endemic in Singapore and the region. Keeping the Aedes aegypti mosquito population low is the most effective dengue control measure. Singapore's vector control programme, aligned with the World Health Organisation's (WHO) Integrated Vector Management strategy, is globally recognised and has significantly reduced dengue transmission over the years.

Our epidemiological investigations and vector control operations have been commended by the WHO as a role model for countries.

Our vector control efforts have led to good outcomes. A joint study with the National University of Singapore showed that Singapore residents are six times less likely to get a first dengue infection today than in the 1970s. While 70 per cent of Singapore youth in the early 1980s had exposure to dengue, only 16 per cent did in 2009. In contrast, 50 per cent to 80 per cent of young people in other endemic countries carry dengue antibodies.

However, this success also means lower population immunity, leaving us susceptible to outbreaks despite having the same number of or fewer mosquitoes.

About 75 per cent of infected people do not show symptoms, enabling virus spread. Climate change and Singapore's status as a global hub also mean we have less control, such as from importation of cases. There is no room for complacency, especially with the recent increase in cases due to dengue virus serotype 3, to which our population has low immunity.

The National Environment Agency continues to work at improving our dengue control system.

In January, we completed the deployment of Gravitrap sensors to private landed estates, complementing those deployed at Housing Board estates since 2017.

These 64,000 Gravitraps help us enhance mosquito monitoring, alert stakeholders and mobilise vector control resources more effectively.

Since last August, we have also made available information on regions with high mosquito populations to facilitate stakeholders taking pre-emptive action to prevent dengue clusters.

Other innovations include using data analytics to mitigate the impact of outbreaks and leveraging technology and novel tools, such as with Project Wolbachia Singapore.

The project involves the release of male Wolbachia-Aedes mosquitoes, and has reduced the urban Aedes aegypti population by over 90 per cent in the Yishun and Tampines study sites.

Efforts of the whole community are needed for effective dengue control.

Chew Ming Fai

Director-General Public Health

National Environment Agency

A version of this article appeared in the print edition of The Straits Times on March 09, 2020, with the headline 'Dengue control measures have significantly reduced transmissions'. Print Edition | Subscribe