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Annex A

Leveraging Science and Technology to Stem Dengue Transmission

NEA regularly explores new tools and technologies to improve dengue control in Singapore. 

Drones Deployment

• To overcome the limitations faced by our officers in inspecting roof gutters, NEA has been deploying drones for the surveillance of roof gutters since 2016, to detect the presence of stagnant water that may lead to mosquito breeding. Where necessary, Bti larvicide is dispensed to destroy any mosquito breeding found in roof gutters with stagnant water.

Artificial Intelligence (AI)

• NEA’s Environmental Health Institute (EHI) worked with a group of researchers from NUS’ Saw Swee Hock School of Public Health, to develop an AI agent to forecast dengue incidence up to four months ahead, by learning the seasonal patterns of dengue cases over the last decade.
• By providing advanced warnings of impending outbreaks, the AI agent can assist NEA to optimise our response. This could include measures such as: mobilising additional officers and community volunteers, intensifying removal of mosquitp breedinghabitats, and providing advice to the public on what the community can do to suppress the mosquito population in their neighbourhoods.
• As more data sources are integrated, the AI agent will potentially be able to predict and localise outbreaks in specific areas of Singapore, by analysing mosquito breeding data and proactively suggesting additional vector control and spot-checking schedules.

Gravitrap Surveillance

• The Gravitrap, developed by NEA’s EHI is designed to attract and trap female Aedes mosquitoes that are looking for sites to lay their eggs. To enhance surveillance efforts, about 50,000 Gravitraps have been deployed islandwide. This in-house developed Gravitrap is one of the first oviiposition traps deployed in the world, and remains cost-effective when compared to other currently available commercial traps. NEA will extend its surveillance programme and progressively deploy Gravitraps to landed estate premises in 2019.

• Female mosquitoes attempting to lay their eggs in these containers will be captured and thus prevented from subsequently biting other people. The Gravitrap also traps and prevents the emergence of any mosquitoes from eggs that are laid in the trap. Gravitraps, when distributed across an area, help to monitor the Aedes mosquito population in the vicinity.

• Knowing which Gravitraps are capturing these mosquitoes helps NEA to prioritise its resources, by directing officers to search for and destroy mosquito breeding habitats at locations with higher Aedes mosquito populations.

Smart Gravitrap

• In collaboration with a local start-up company, Orinno Technology Pte. Ltd. (OTPL), NEA’s EHI has developed a Smart Gravitrap prototype which will enable remote data collection and analysis. The Smart Gravitrap is currently under development, and may enhance the way NEA officers collect data on the mosquito population in future, thus leading to more effective Aedes surveillance and better dengue control.

• An assembly of sensors installed in the Smart Gravitrap is triggered when an insect enters the trap. It then captures the signature of signals generated by the flight of the insect and sends the information to a back-end server, which hosts an identification algorithm and database of signatures unique to different species of mosquitoes. The signatures are also unique to the genders of each species of mosquito. The artificial intelligence is thus able to identify the insect that has been trapped by the Smart Gravitrap.

Project Wolbachia – Singapore

• NEA has embarked on Project Wolbachia – Singapore, using male Wolbachia-carrying Aedes aegypti mosquitoes to further suppress the urban Aedes aegypti mosquito population in the community. When male Wolbachia-Aedes aegypti mosquitoes mate with female Aedes aegypti without Wolbachia, their resulting eggs do not hatch. The novel method was developed to complement existing dengue control strategies in Singapore.

Aedes Mosquito Population Suppression Achieved in Phase 1 and 2 Field Studies

Phase 1 Field Study

• In the Phase 1 field study, a 50% suppression of the urban Aedes aegypti mosquito population was obtained. At sites where the male Wolbachia-Aedes mosquitoes were released, much fewer Aedes aegypti adult mosquitoes were found. At these sites, half of the collected Aedes aegypti mosquito eggs did not hatch, providing strong indication that the released Wolbachia-Aedes males had successfully competed with the urban Aedes males and mated with some of the urban Aedes aegypti females.

   

  

  Fig. 1. Phase 1: Infographic showing the impact of male Wolbachia-Aedes mosquitoes on the urban Aedes aegypti mosquito population at the study sites

  Phase 2 Field Study

• In the Phase 2 field study, an 80 per cent and 70 per cent suppression of the urban Aedes aegypti mosquito population was obtained at the Nee Soon East and Tampines West study sites respectively. The expanded areas of the release sites, and the high floor releases of male Wolbachia-Aedes mosquitoes (in addition to ground floor releases), had led to a better outcome. The results show that a larger release site yields better results, and community efforts to remove mosquito breeding habitats will enhance the effectiveness of the technology.

   

  

  Fig. 2. Phase 2: Infographic showing the impact of male Wolbachia-Aedes mosquitoes on the urban Aedes aegypti mosquito population at the study sites

  Phase 3 Field Study

•  NEA has commenced the Phase 3 Field Study in February 2019, which aims to determine if suppression of the urban Aedes aegypti mosquito population can be sustained in larger areas. The Nee Soon East and Tampines West study sites will be expanded by between 1.6 to 2.2 times, compared to the Phase 2 field study areas. In the long-term, this will require strategies which reduce the number of male Wolbachia-Aedes mosquitoes being released in an area, to make the technology more sustainable.

  Innovations for Mosquito Production Solutions 
  

• Mosquito rearing is laborious and time-consuming, with very little technological support, despite advances in engineering and artificial intelligence solutions in other fields. NEA’s EHI and Orinno Technology Pte. Ltd. (OTPL), a local start-up company, have thus come together to develop various process modules and novel devices that have helped to improve the production efficiency and quality of the Wolbachia-Aedes mosquitoes required for field releases.

• Thus far, the larvae counter has yielded successful results, and has shortened the time required to fill a tray of water with 4,000 larvae from two hours to less than three minutes. This has effectively enhanced the mass production and sorting of male mosquitoes required for the Project Wolbachia field study in Singapore. Using a similar engineering concept, another innovation currently being used in mosquito production is the pupae counter – an automated device that can accurately count and dispense the desired number of male Wolbachia-Aedes pupae into each release container.

• Other devices under development include: an automated feeding system, a pupae separator, and an adult mosquito sex sorter. These devices will not only help to save manpower and costs, but will also ensure the consistency and quality of the male mosquitoes produced and released.

• The most recent innovation is the mosquito launcher – a lightweight and portable release device, designed to efficiently and systematically store, transfer and release male Wolbachia-Aedes mosquitoes at Singapore’s high-rise residential blocks.

• As a result of these creative solutions, five intellectual property patents have been filed for these novel devices. The devices have received interest from other international programmes that are also producing male mosquitoes for suppression of the mosquito populations in their communities.

Devices Developed/ Being Developed

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