Lab-grown mosquitoes fight dengue in Singapore

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RESEARCHERS at the National Environment Agency (NEA) of Singapore have devised a method to utilise mosquitoes to combat the spread of dengue through an initiative named Project Wolbachia.

Project Wolbachia has been on-going in the island state since 2016, and has been divided into five phases, with the fourth phase currently in session. Specially-bred Aedes aegypti mosquitoes in government laboratories are cultivated to carry a species of bacteria called Wolbachia.

Wolbachia causes gamete cells to be altered thus disabling them to be viable offsprings.

Wolbachia is a naturally-occurring bacterium that is found in around 60 percent of insects, but is not native to the Aedes aegypti species.

The process involves injecting the bacteria into newly laid mosquito eggs, infusing the hatched larvae with the bacteria.

This first generation eventually reproduces, which leads to the production of bacteria-carrying offspring. The eggs from the offspring are allowed to hatch and the male pupae are segregated and left to grow.

When they are adults, they are released in areas that have a high rate of dengue infection. According to the agency, up to six mosquitoes are released each week per person in the participating areas.  These male Wolbachia-Aedes mosquitoes do not bite and infect humans, and thus do not pose a threat to the community. They are also effectively sterile due to the presence of the bacteria in their bodies when the males mate with the non-bacteria carrying females. The resultant eggs from the mating process are unable to hatch, which consequently prevent offspring from being produced and  help reduce the population of  dengue-causing mosquitoes.

The phased approach adopted by the NEA, under the recommendation of the World Health Organization (WHO), has achieved laudable results, with Phase 1 suppressing 50 percent of Aedes aegypti populations in the targeted area, Phase 2 suppressing 70 to 80 percent, and Phase 3 suppressing up to 90 percent.

The Singapore  government reports that during Phase 4, 65 to 80 percent fewer dengue cases were recorded in areas with Wolbachia mosquitoes as compared to the areas where they were not released.