NEA calls tender for dengue battle plan

National Environment Agency (NEA) workers spraying insecticide in a garden to kill the larvae of the Aedes mosquito.  The NEA has put up a tender for proposals to study the possible side effects of using male Wolbachia-carrying mosquitoes to fig
National Environment Agency (NEA) workers spraying insecticide in a garden to kill the larvae of the Aedes mosquito.  The NEA has put up a tender for proposals to study the possible side effects of using male Wolbachia-carrying mosquitoes to fight dengue. -- PHOTO: ST FILE

It seeks proposals to study use of Wolbachia-carrying mosquitoes

Singapore's plan to use a special type of mosquito to combat the dengue virus here is about to take another step forward.

The National Environment Agency (NEA) has put up a tender to ask for proposals to study the possible side effects of using male Wolbachia-carrying mosquitoes to fight the virus.

This method to reduce dengue infections uses male Aedes aegypti mosquitoes infected with the Wolbachia bacteria, which makes them sterile.

These male mosquitoes, which do not bite, are released so they mate with the female dengue-spreaders.

These female mosquitoes will then produce eggs that do not hatch.

Over time, this can help to reduce the population of Aedes mosquitoes in Singapore, and hopefully reduce the rate of dengue infections.

The NEA noted in its tender documents that such Wolbachia-carrying mosquitoes are a promising tool for dengue control in Singapore.

However, "careful assessment of the safety and effectiveness of the technology in Singapore's environment is essential prior to its use", the NEA said.

The contractor who wins the tender will review projects in other countries that have used the Wolbachia-carrying mosquitoes, and consult experts, to determine all possible unintended consequences of using the mosquitoes.

These include ecological, economic and public health consequences, as well as those that are "positive, negative, direct, indirect, secondary, cumulative, temporary and permanent, reversible and irreversible, and in the short, medium and long term".

The contractor will also come up with ways to monitor and mitigate any undesirable consequences, where possible.

Experts told The Straits Times that trials in Australia, Indonesia and Vietnam using the mosquitoes have not resulted in any negative side effects.

Professor Duane Gubler, an epidemiologist at Duke-NUS Graduate Medical School's Programme on Emerging Infectious Diseases, who is also chair of the NEA's Dengue Expert Advisory Panel, noted: "The NEA is covering all of its bases with the tender.

"It wants to make sure it has all of the information available, and that is the right thing to do."

Dengue is endemic in Singapore and the region.

There were 2,159 dengue cases and one death here in the first 12 weeks of this year, compared to 17,600 cases and five deaths last year.

zengkun@sph.com.sg