Townsville has become home to a modified population of mosquitoes in a measure to curb outbreaks of dengue in the country.

Australian medical entomologist, Professor Scott O’Neill, recently convinced the residents of Townsville to become a haven for disease-resistant mosquitoes, in a bid to stop the spread of dengue and other viruses.

About 7000 families became nannies for the mosquitoes, with each hosting a tub of Aedes aegypti eggs in their yard, stocked with fish food to nourish their little charges as they develop and take flight. The insects are part of a project by the non-profit World Mosquito Program, with regional hubs at Monash University in Melbourne and Ho Chi Minh City, Vietnam, to fight annual outbreaks of dengue fever.

The mosquitoes – about 4 million in all, infected with a bacterium called Wolbachia, which reduces their ability to transmit dengue, Zika, and chikungunya viruses – were released to mate with local mosquitoes. Although found in around 60% of insects species naturally, Wolbachia is not normally found in Aedes aegypti mosquitoes and therefore if the number of Wolbachia-containing mosquitoes builds up in the population, in theory the amount of dengue transmission should decrease.

According to Professor O’Neill, director of the World Mosquito Program based at Melbourne’s Monash University, the city has been dengue-free since 2014.

“The community embraced the project, with even school children releasing the special mosquitoes that passed on their bacteria to the local population of mosquitoes,” Professor O’Neill said.

“At a cost of around $15 per person, the Townsville trial demonstrates the approach can be rolled out quickly, efficiently and cost effectively to help provide communities ongoing protection from mosquito-borne diseases.”

The program is currently working in 11 countries and aims to deploy the Wolbachia mosquitoes in larger and poorer parts around the world with a target of reducing the cost to just US$1 per person. The next step for the team is in Yogyakarta in Indonesia — a city of nearly 390,000 — where a randomised controlled trial is under way.

According to Professor O’Neill, Townsville had experienced local transmission outbreaks every year for 10 years preceding the intervention, but no dengue transmission has occurred since the trial started in 2014.

“This study was not set up as an experimental, epidemiological trial. We’re actually doing that in Indonesia at the moment — a randomised, controlled trial, which will read out in about 18 months. But this is showing extremely encouraging evidence as we lead up to that piece of work,” Professor O’Neill said.

Reworked extract from: ‘This Scientist Convinced An Australian City To Become A Haven For Mosquitoes’, by Kelly Servick, Sciencemag. Org, 1 August, 2018, and; ‘Dengue Fever Outbreak Stopped By Special Mosquitoes’, BBC News, 1 August, 2018.