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Minister for Sustainability and the Environment, Grace Fu, announced on Jun. 15 that the National Environment Agency (NEA) will be releasing male Wolbachia-carrying Aedes aegypti mosquitoes (Wolbachia-Aedes) in 1,400 additional HDB blocks across Singapore from July 2022.
Fu was delivering the keynote address at the fifth Asia Dengue Summit that took place from Jun. 13 to 15.
The expansion of the releases of male Wolbachia-Aedes mosquitoes will complement existing community efforts to combat dengue.
Which areas will it cover?
Dengue clusters in Singapore. Image via NEA.
The sites selected are based on a set of criteria – historical dengue risk level, Aedes aegypti population, the size and landscape of the area, and NEA’s capacity for producing and releasing male Wolbachia-Aedes mosquitoes.
Eight new locations will be covered:
- Bedok North
- Bedok Reservoir
- Choa Chu Kang (Yew Tee)
- Geylang
- Hougang
- Punggol
- Sengkang
- Woodlands
Fu shared that community and residents of release areas will be informed prior to the start of the releases.
NEA first started this initiative, called Project Wolbachia, in 2016, covering only 39 HDB blocks and over 3,900 homes.
Today, the project covers about 1,800 HDB blocks in Yishun, Tampines, Choa Chu Kang and Bukit Batok towns, and within five square kilometres of the landed estate at Marine Parade, which comprises some 160,000 homes.
With the expansion, the total coverage of the project will increase from the current 19 per cent of all HDB blocks in Singapore, to 31 per cent, comprising more than 300,000 households.
Has the project been working?
NEA said 2022 has been a "challenging year thus far as we faced an early surge in dengue cases and numbers are expected to hit a record high".
Singapore has already seen more than 14,000 dengue cases this year.
This exceeds the total of 5,258 dengue cases reported in 2021.
The releases of male Wolbachia-Aedes mosquitoes will suppress the urban Aedes aegypti mosquito populations in these sites, and the data collected will also allow NEA to determine the impact of the technology on dengue cases and clusters.
"The results have been promising thus far," NEA said in the press release.
Image via NEA Stop Dengue Now/FB.
When male mosquitoes infected with the Wolbachia bacteria are released and mate with urban female Aedes aegypti that do not carry Wolbachia, their resulting eggs do not hatch.
This reduces the overall Aedes aegypti population.
Tampines and Yishun, where there has been more than one year of releases, have previously seen up to 98 per cent reduction in the dengue mosquito population and up to 88 per cent reduction in dengue cases.
During the current dengue outbreak, the two areas have seen 70 per cent fewer dengue cases compared to similar areas without Wolbachia.
NEA said: "The positive outcome of the field studies at release sites has shown that continued releases of male Wolbachia-Aedes mosquitoes can successfully suppress the female urban Aedes aegypti mosquito population in Singapore."
NEA will increase the number of male Wolbachia-Aedes mosquitoes produced per week from the current two million to five million by the end of 2022.
Continue to be vigilant
Professor Duane Gubler, dengue expert advisory panel chairman and emeritus professor at Duke-NUS Medical School, Singapore said:
"Business-as-usual is not an option given the escalating threats of dengue. Novel technologies, including Wolbachia and dengue vaccines, provide new tools to complement and strengthen existing dengue control efforts, and prevent epidemic transmission of this disease."
NEA warned that even as Project Wolbachia expands to more areas, the "technology is not a panacea and its effectiveness can be hindered by mosquito breeding in the community".
Residents and businesses need to ensure good housekeeping to keep homes, premises and estates free from mosquitoes and dengue.
Associate professor Ng Lee Ching, group director of NEA's Environmental Health Institute said the community needs to cooperate with the programme to prevent "the resurgence of mosquito abundance", which can reverse the impact achieved by the technology, by removing mosquito breeding habitats.
"It is thus important for the community to continue staying vigilant and take steps to fight dengue," Gubler added.
Here are a few tips to prevent mosquito breeding habitats:
Top image via Zhangxin Zheng.