Written Reply to Parliamentary Questions on Dengue

Written Reply to Parliamentary Questions on Dengue by Ms Grace Fu, Minister for Sustainability and the Environment

Dr Syed Harun Alhabsyi: To ask the Minister for Sustainability and the Environment in light of the heightened numbers relating to dengue infections in 2024 (a) what are the steps taken to ameliorate the dengue infection rate for the year and beyond; and (b) what has been the progress of previous initiatives to arrest dengue infection trends and whether they continue to be effective.

Ms Hany Soh: To ask the Minister for Sustainability and the Environment in light of NEA’s Q2 2024 Dengue Surveillance Data published on 24 July 2024, whether the NEA will review its dengue prevention strategies to further improve their efficacy.

Answer:

1 The weekly number of dengue cases has remained high since the start of 2024, with over 10,400 dengue cases reported by end July. This is more than the 9,949 dengue cases reported in the whole of 2023. The Aedes aegypti mosquito population has also remained high. The low immunity of our population to all four Dengue virus serotypes, coupled with the warm and humid weather which accelerates the development of the Aedes mosquito and multiplication of the Dengue virus, presents a continued dengue transmission risk.

2 Given the continued presence of these risk factors, the National Environment Agency (NEA) has been working with partner agencies and Town Councils to intensify inspections, and conduct flushing of drains and chemical treatment in dengue cluster areas in order to remove potential sources of mosquito breeding and suppress the adult mosquito population. NEA also launched the annual National Dengue Prevention Campaign on 31 March 2024, ahead of the traditional peak dengue season from May to October, to rally members of the public and stakeholders to take immediate action to reduce mosquito breeding and protect themselves against dengue. NEA has been working with grassroots organisations, non-governmental organisations such as social service agencies, and schools to promote dengue prevention messages on their digital communication platforms or through their events. NEA deployed volunteers to areas with high footfall, such as hawker centres and transport hubs, and worked with supermarket operators to ramp up awareness of the dengue situation.

3 With these collective efforts, we have seen positive results thus far. In the second quarter of 2024, the number of dengue cases decreased by 20.8% and the number of dengue clusters decreased by 16%, compared to the first quarter of 2024.

4 NEA’s Project Wolbachia has seen positive results across all study sites. We have generally observed 80-90% reduction in the Aedes aegypti mosquito population in these sites after 6 to 12 months of releases. We have been expanding the project in phases, covering 480,000 households since March 2024. In addition, we will continue to conduct field studies to further understand the environmental factors affecting the efficacy of Project Wolbachia in dengue risk reduction in order to improve our deployment strategy and enhance its cost-effectiveness before expanding the programme to cover more areas.

5 Nevertheless, Project Wolbachia is not a silver bullet. Collective action by stakeholders and residents to prevent mosquito breeding remains critical to reducing the risk of dengue transmission. All of us need to play our part to ensure that our homes and surroundings are free of stagnant water, and to take precautions if we are residing in dengue cluster areas, such as spraying insecticides in dark corners, applying insect repellent and wearing long sleeves and pants.