At the heart of the program is an innovation from WMP, which was the first to introduce the use of Wolbachia, a bacterium that blocks the dengue virus and other pathogens such as Zika, chikungunya and yellow fever, preventing them from growing in the bodies of the Aedes aegypti mosquitoes that normally transmit these viruses.

Female mosquitoes infected with the bacteria pass the bacteria on to their offspring. It also shortens their life expectancy and thus contributes to a reduction in population density in particularly affected areas.

The method has already proven to be extremely effective. In recent trials across Colombia, researchers reported a 94 percent reduction in dengue infections, bringing the number of cases to its lowest level in 20 years.

Previous attempts to release Wolbachia-infected mosquitoes were done from the ground, releasing clouds of adult mosquitoes from tubes, often from car windows.

Dr Colin Malcolm, lecturer in genetics at the School of Life and Medical Science at the University of Hertfordshire, said the difficult terrain posed a challenge for teams on site.

“We’re talking about areas that can be quite crowded, as dengue is often associated with populated, poverty-stricken areas,” he told The Telegraph. “The complications can be poor sanitation, poor hygiene and poor roads, which mean it’s difficult to get around by car.”

Another challenge was the sheer number of places where mosquitoes can breed.

“These could be flower vases, gutters or water storage tanks,” says Dr. Oliver Brady, associate professor at the London School of Hygiene and Tropical Medicine.

“This is where Wolbachia comes in as a possible solution. Because instead of having to kill every single mosquito out there, you try to replace the natural mosquito population with one that cannot transmit dengue fever.”