Project to fight dengue set to cover a third of all HDB blocks

A national project to fight dengue using specially bred male mosquitoes will be scaled up significantly to reach nearly a third of all Housing Board blocks here from next month. This comes amid concerns that infections here will continue rising.

Weekly cases may soon cross 2,000, said Minister for Sustainability and the Environment Grace Fu yesterday. This means they will surpass the highest weekly figure of 1,787 cases, seen in 2020.

To rein these in, she announced that Project Wolbachia, which has been effective in controlling the population of dengue-spreading mosquitoes, will be expanded to another 1,400 HDB blocks from next month.

This means the project, currently active in 1,800 blocks, will cover more than 300,000 homes, nearly twice the 160,000 homes currently, and about 31 per cent of HDB blocks in Singapore.

She was delivering the keynote address at the fifth Asia Dengue Summit, which brought together more than 200 experts and policymakers from across Asia to discuss dengue management strategies for the region.

As at Tuesday, more than 15,000 cases of dengue have been reported in Singapore this year. The numbers are expected to rise even further as the nation has entered the traditional peak dengue season, which usually lasts from June to October.

Professor Duane Gubler, dengue expert advisory panel chairman and Emeritus Professor at Duke-NUS Medical School, said "business as usual" is not an option given the escalating threat 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," he said.

Launched in 2016, the project involves the release of male Aedes aegypti mosquitoes infected with the Wolbachia bacteria at selected sites. When female Aedes mosquitoes which are not infected with the bacteria mate with the males, they produce eggs which do not hatch, thus reducing the population of Aedes aegypti mosquitoes - the main vector of dengue here.

Speaking at the conference yesterday, Associate Professor Ng Lee Ching, group director of the Environmental Health Institute at the National Environment Agency (NEA), said that Project Wolbachia has had an "eraser effect" at its current deployment sites, reducing the incidence of dengue in areas such as Tampines and Yishun by up to 70 per cent so far this year. "The results in existing study sites (have) shown the effectiveness of the Wolbachia technology in the reduction of Aedes aegypti mosquito population in these areas," she said.

Ms Fu said that the expansion of the trial, which will see Project Wolbachia deployed at a total of 13 sites, up from the current five, will allow the authorities to understand the impact of large-scale multi-site deployments.

The additional eight sites are: Bedok North, Bedok Reservoir, Choa Chu Kang (Yew Tee), Geylang, Hougang, Punggol, Seng-kang and Woodlands.

The sites were chosen based on several factors: historical dengue risk level, Aedes aegypti population, the size and landscape of the area, and NEA's capacity for producing and releasing the mosquitoes.

Ms Fu added that good environmental management to prevent the breeding of mosquitoes is the cornerstone of NEA's dengue control programme.

A person living in Singapore today is 10 times less likely to get infected with dengue for the first time than someone here in the 1960s, said the minister.

But she noted that this also means there is falling population immunity to dengue here.

And, while Wolbachia technology is promising, it is not an instant, one-stop solution to the dengue problem, said Ms Fu.

"Ultimately, individual and community responsibility and actions are still the most critical elements of dengue control."