Following successful field studies at Yishun and Tampines towns, NEA will release male Wolbachia-Aedes mosquitoes at selected dengue high-risk areas – in neighbourhoods at Choa Chu Kang and Bukit Batok towns – from May 2020, in a more targeted approach to test different strategies to suppress urban Aedes aegypti mosquito populations
Singapore, 6 May 2020 – Project Wolbachia – Singapore has achieved more than 90 per cent suppression of the urban Aedes aegypti mosquito population at existing study sites at Yishun and Tampines towns, and has kept these populations at low dengue-risk levels for more than a year. In May 2020, the National Environment Agency (NEA) will expand releases of male Wolbachia-carrying Aedes aegypti (Wolbachia-Aedes) mosquitoes to selected dengue high-risk neighbourhoods at Choa Chu Kang, Keat Hong and Hong Kah North, which have high Aedes aegypti mosquito populations. With a total area less than the current Project Wolbachia – Singapore areas at Yishun and Tampines towns, the research objective of this targeted release is to test different strategies, to determine the most effective and impactful approaches for future wider scale deployment for Project Wolbachia - Singapore.
Wolbachia technology successfully field-tested at Yishun and Tampines
2 The Aedes aegypti mosquito is the primary vector of dengue, chikungunya and Zika viruses in Singapore. Since 2016, NEA has conducted phased field studies at Yishun and Tampines towns, to evaluate the use of male Wolbachia-Aedes mosquitoes to suppress the urban Aedes aegypti mosquito populations. When released male Wolbachia-Aedes mosquitoes mate with urban female Aedes aegypti mosquitoes, the resulting eggs do not hatch. Over time, continued releases of male Wolbachia-Aedes mosquitoes are expected to gradually reduce the urban female Aedes aegypti mosquito population, and hence lower the risk of dengue transmission.
3 Project Wolbachia – Singapore is now in its Phase 4 field study. In areas with reduced urban Aedes aegypti mosquito populations, fewer male Wolbachia-Aedes mosquitoes were needed to maintain the suppression. As for an epidemiological link, NEA’s preliminary analysis of 2019 data showed that there were 65 to 80 per cent fewer dengue cases at the Yishun and Tampines study sites where releases had been carried out, compared to at the sites without releases.
Testing of targeted deployment strategy at Choa Chu Kang and Bukit Batok towns
4 Following the success of the field studies at Yishun and Tampines, NEA will expand releases of male Wolbachia-Aedes mosquitoes to 207 blocks in selected neighbourhoods at Choa Chu Kang, Keat Hong and Hong Kah North, in May 2020. The neighbourhoods were selected due to their consistently high Aedes aegypti mosquito populations (see maps in Annex A), and hence higher risk of dengue clusters forming there.
5 “Project Wolbachia – Singapore at Yishun and Tampines towns has been adopting a rolling approach, with the gradual expansion of release sites to adjacent neighbourhoods within each town. At Choa Chu Kang and Bukit Batok towns, the study will take a more targeted approach and zero in on selected neighbourhoods with consistently high Aedes aegypti mosquito populations, to preemptively suppress the Aedes aegypti mosquito populations” said Associate Professor Ng Lee Ching, Director of NEA’s Environmental Health Institute (EHI).
6 The total area of the new release sites at Choa Chu Kang, Keat Hong and Hong Kah North is less than the current Project Wolbachia – Singapore areas at Yishun and Tampines towns. NEA researchers will similarly be releasing male Wolbachia-Aedes mosquitoes at public spaces around houses and blocks. Release points may include stairwells, void decks, and open spaces between blocks of high-rise homes. The male Wolbachia-Aedes mosquitoes will not be released directly into homes. While residents may see more of these male mosquitoes, they will not attract female mosquitoes to the area. Residents do not have to do anything differently, and should continue to stay vigilant and carry out mosquito control procedures as usual. NEA estimates that an average of six or fewer male mosquitoes per person will be released regularly. NEA will be engaging residents and local stakeholders at the release sites in the coming months.
7 NEA continues to develop and test automated solutions to ramp up production of Wolbachia-Aedes mosquitoes, so that releases can be extended to more areas with high Aedes aegypti mosquito population in future. The targeted expansion of Project Wolbachia – Singapore to Choa Chu Kang, Keat Hong and Hong Kah North is supported by NEA’s new mosquito production facility, which officially opened in December 2019. Meanwhile, NEA will continue with the current releases in the ongoing Phase 4 field study at Yishun and Tampines towns, which involves 553 blocks in total, or an about 14-fold expansion compared to in Phase 1 in 2016.
Wolbachia technology is safe
8 The Wolbachia bacterium carried by the released male mosquitoes is safe. Wolbachia occurs naturally and is found in more than 60 per cent of insect species, including butterflies, fruit flies, dragonflies, and various mosquito species. As male mosquitoes do not bite, the release of male Wolbachia-Aedes mosquitoes will not pose any additional risk of biting or disease transmission. On the contrary, the risk of dengue transmission could be lowered if the study successfully reduces urban Aedes aegypti mosquito populations in the community. Members of the public are encouraged to find out more about Wolbachia technology at the Project’s website: https://www.nea.gov.sg/corporate-functions/resources/research/wolbachia-aedes-mosquito-suppression-strategy
Concerted community efforts needed to tackle current dengue situation
9 With the relatively high number of weekly cases, ranging between 300 to 400 cases, in the first four months of this year, the number of dengue cases in 2020 is projected to exceed the 16,000 cases in 2019. While the results so far indicate that Wolbachia-Aedes mosquito releases are effective at suppressing the urban Aedes aegypti mosquito populations as well as dengue cases, the technology is not a silver bullet. Wolbachia-Aedes mosquito releases are currently only being conducted in a small number of neighbourhoods, and are intended to complement – not replace – traditional vector control measures, such as comprehensive mosquito surveillance, source reduction of mosquito breeding habitats, and use of insecticides where necessary. It is therefore critical for the public to remain vigilant and regularly practise the Mozzie Wipeout, so that our neighbourhoods and homes can be kept free of mosquitoes and dengue.
~~ End ~~
For more information, please submit your enquiries electronically via the Online Feedback Form or myENV mobile application.
ANNEX A
LOCATION MAPS OF RELEASE SITES (DEMARCATED BY DOTTED LINES)
Location Map of Release Site at Choa Chu Kang
Location Map of Release Site at Keat Hong
Location Map of Release Site at Hong Kah North