Ugandan scientists create new sterile mosquito breed to fight malaria

Scientists at the Uganda Virus Research Institute are developing a new breed of mosquitoes that they say could help cut the population of insects that spread malaria in Uganda.

The work is being carried out under Target Malaria Uganda, a research project studying genetic approaches that could one day reduce the number of female malaria-carrying mosquitoes. 

Krystal Birungi, a research and outreach associate at the project, said their aim is to sharply reduce egg laying and the number of biting females.

“We are going at this by targeting reduction of the number of eggs that these mosquitoes lay. A single mosquito can lay up to 300 eggs at once. So, we are saying, instead of laying 300 eggs, what can we do to see that they lay only 10 or none at all,” Birungi said.

She said in an interview with NTV, that the team has already bred mosquitoes that produce about 90 per cent males, a milestone that could lower the number of female mosquitoes, which are the ones that bite and lay eggs.

Target Malaria is focusing on reducing female vector mosquitoes because they drive future population growth and are responsible for transmitting malaria. 

The project is also studying a strain in which fertile males carry a gene that could make female offspring sterile if inherited from both parents, as well as a male-bias strain that produces mostly male offspring. 

The scientists say the work is still at an early stage and remains under containment rather than field use in Uganda. 

Target Malaria said in a 2024 update that the male-bias strain imported into Uganda does not yet carry gene-drive technology and is being used for contained studies to confirm that it produces more male than female offspring and to understand how the mosquitoes develop and behave. 

The organisation says the strain can produce up to 95 per cent male offspring under laboratory conditions

That means the research is not yet being deployed as a public vector-control tool. 

Instead, scientists are using it to build evidence, train teams and prepare for future regulatory review. Target Malaria says any long-term use would be intended to complement, not replace, existing tools such as treated nets, spraying, diagnosis and treatment.

The research is taking place against the backdrop of a heavy malaria burden in Uganda. 

The World Health Organization said malaria remains one of the deadliest diseases in the country. 

Malaria accounts for up to 40 per cent of outpatient visits, 25 per cent of hospital admissions and 14 per cent of hospital deaths in Uganda. In 2023, Uganda was among the five African countries with the highest malaria burden.

Uganda has recently expanded its response, including the rollout of the R21/Matrix-M malaria vaccine for children in high and moderate transmission districts. 

WHO says the vaccine programme initially targets 1.1 million children under two years in 105 districts.