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[NAIROBI] An ’oral contraceptive‘ to sterilise male Anopheles mosquitoes is being developed by the Kenya Medical Research Institute (KEMRI) to help reduce mosquito populations and cut malaria transmission in Africa.
According to the World Health Organisation (WHO), malaria caused close to 650,000 deaths globally in 2012. Those at risk are pregnant women and children below the age of five in developing nations.
Njagi Kiambo, an entomologist with Kenya’s Ministry of Health Division of Malaria Control, says emerging resistance to insecticides and medicines for controlling malaria, including artemisinin-based combination therapy, makes it crucial to try new approaches for fighting the disease.

“If the male mosquitoes become infertile after feeding on that meal, they will not be able to impregnate their female counterparts who transmit malaria parasites to human beings.”

Luna Kamau, Kenya Medical Research Institute (KEMRI)

“We are designing special containers where we will put sugar spiced with the contraceptive,” says Dr Luna Kamau, the study’s principal investigator with KEMRI Centre for Biotechnology Research and Development.
Kamau adds that the containers, which will also have carbon dioxide aimed at attracting the male mosquitoes, will be placed strategically around breeding places and houses frequented by these insects.
 “If the male mosquitoes become infertile after feeding on that meal, they will not be able to impregnate their female counterparts who transmit malaria parasites to human beings,” Kamau explains.
According to Kamau, they are testing three chemicals - two are synthetic compounds while the other is derived from a Kenya-based plant. 
The study, currently at the laboratory stage, started in June 2012 with US$100,000 funding from the Grand Challenges Explorations of the Bill and Melinda Gates Foundation and will end in April 2014.
Kiambo says both male and female mosquitoes feed on nectar from flowers to get energy but the females need to feed on blood when breeding in order to produce eggs.
“So if they [the mosquitoes] get it [the blood] from a person infected with malaria, they will pick the disease parasite and spread it to other healthy individuals they bite,” he adds. 
Kamau explains that a female Anopheles mosquito mates only once in her lifetime. The sperms she receives are then stored within her body in a special sac known as spermatheca, which will be used to fertilise future batches of eggs that the mosquito will lay.
“And since females can’t differentiate between sterile and fertile males, those mated with the former will virtually not have a chance at reproduction,” he notes.
“We are testing sperm production in mosquitoes who consume contraceptives as well as their preference or avoidance of meals with them,” says Kamau “We are also trying to find out if the contraceptives affect male mosquitoes’ ability to compete effectively with others for female mates.”
The researchers are also investigating reproductive outcomes of females such as quality of eggs they lay upon mating with male mosquitoes given the contraceptives.
This article has been produced by SciDev.Net's Sub-Saharan Africa desk.

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