This is a full version of NEA’s reply issued to the media agency; published in The Straits Times, 9 Mar 2020.
NEA's vector control programme has reduced dengue transmission in Singapore over past 50 years
We thank Mr Teo Yew Cheng for his letter (‘Fight against coronavirus laudable, but what about dengue effort?’, Feb 24).
Dengue is endemic in Singapore and the region. Transmission is due to the Aedes aegypti mosquito vector, which breeds largely in man-made containers and our homes.
Keeping the mosquito population low is the most effective dengue control measure. Singapore’s vector control programme, aligned with the World Health Organization (WHO)’s 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 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. Whilst 70% of Singapore youths in the early 1980s had exposure to dengue, only 16% did in 2009. In contrast, 50 to 80% of youths in other endemic countries carry dengue antibodies.
However, this success also means lower population immunity, leaving us susceptible to outbreaks despite having the same or fewer mosquitoes. About 75% of infected persons do not show symptoms, enabling virus spread. Climate change and Singapore’s status as a global hub also mean we have lesser 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 (DENV-3), to which our population has low immunity.
The National Environment Agency (NEA) continues to work hard at improving our dengue control system. In January 2020, we completed the deployment of Gravitrap sensors to private landed estates, complementing those deployed at HDB estates since 2017. These 64,000 Gravitraps help us enhance mosquito monitoring, alert stakeholders and mobilise vector control resources more effectively. Since August 2019, we have also made available information on regions with high mosquito population, to facilitate stakeholders taking preemptive 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, where the release of male Wolbachia-Aedes mosquitoes has reduced the urban Aedes aegypti population by over 90% at the Yishun and Tampines study sites.
As the mosquito population is dependent on available breeding habitats, efforts of the whole community are needed for effective dengue control. All residents and stakeholders are reminded to maintain vigilance and Do the Mozzie Wipeout regularly.
Mr Chew Ming Fai
Director-General Public Health
National Environment Agency