NEA to test releasing Wolbachia mosquitoes via drone
Fight against dengue through use of Wolbachia-Aedes technology has been positive so far
The third-phase field study of Singapore's stealth weapon against dengue has been a success, achieving 90 per cent suppression of the urban Aedes aegypti mosquito population at test sites. It paves the way for an expanded fourth-phase study next month.
This will involve the release of mosquitoes via drones, said the National Environment Agency (NEA) yesterday. Called Project Wolbachia, it is a programme where male mosquitoes carrying the Wolbachia bacterium mate with females, causing them to lay eggs that do not hatch.
NEA has been studying the programme since 2012.
The project's third phase, which began in February, has achieved more than 90 per cent suppression of the urban Aedes aegypti mosquito population at its Nee Soon East and Tampines West study sites.
This is an improvement from the 70 per cent to 80 per cent suppression achieved in the second phase, which ended last December, and 50 per cent to 57 per cent in its first phase, which ended in December 2017.
This demonstrates the effectiveness of Wolbachia-Aedes technology in Singapore's landscape, said NEA.
Dengue Expert Advisory Panel chairman Duane Gubler, founding director of the Emerging Infectious Diseases Programme at Duke-NUS Medical School, said: "We are optimistic this method, when fully implemented, will tip the balance in favour of dengue control."
NEA said continued releases have kept the mosquito population at levels that pose low dengue risk.
A total of 12,572 dengue cases were reported from the start of this year until 3pm last Friday. The number of reported cases a week has been falling steadily, hitting 203 in the week ending last Friday, from 327 in the first week of September.
As part of the project's fourth phase, NEA plans to release infected mosquitoes to 163 residential blocks in Nee Soon East and 121 blocks in Tampines West, an area nearly twice the size of the previous phase.
Associate Professor Ng Lee Ching, director of NEA's Environmental Health Institute, said the larger release area would help the agency demonstrate better efficacy of the programme, showing the same success rate could be achieved with a smaller number of mosquitoes released for each block.
"Our systematic approach is needed to derive good comparative results, and a consistent and comprehensive dataset, to ensure robustness of the study before scaling up to more areas beyond Yishun and Tampines."
NEA said it will continue to work with companies to enhance efficiency and quality in the production and release of mosquitoes. It cautioned that the project is "not a silver bullet" in the fight against dengue.
"Breeding of mosquitoes in the community will cancel out the positive impact of the technology. It is therefore important that the community continues to prevent and remove mosquito breeding habitats, so that fewer male Wolbachia-Aedes mosquitoes have to be released for the technology to be successful," it said.