Thanks to an extensive collection and analysis campaign completed this month by the Ministry of Health, researchers now know more than ever about the mosquitoes that carry malaria in Cambodia.
Hundreds of mosquitoes collected across the country since 1999 were sent to labs in France, Belgium and Britain, said Dr Duong Socheat, head of the National Malaria Center. The tests revealed exactly what species and types of mosquitoes are spreading malaria, which will lead to a better strategy for educating against and preventing the disease.
In Cambodia, the two main culprits are Anopheles Minimus and Anopheles Dairus, two of four species of mosquitoes that carry malaria. Malaria is one of the top killers of the Cambodian adult population.
“Nowadays, we are studying more deeply these two species,” said Dr Tho Sochetra, the National Malaria Center’s expert on the anatomy and habits of the mosquito, who explained some interesting facts about the insect.
First interesting mosquito fact: all the biters are female. Male mosquitoes survive off of the nectar of flowers. It is the female that requires blood to live and reproduce. Males spend most of their 10- to 20-day lives hanging around, waiting to breed.
The life of an average mosquito goes something like this: Once laid on the surface of still water in the shade, they move from the egg to larva to pupa stages in between 48 and 72 hours. An average female can lay nearly 100 eggs, with a high survival rate. Males emerge first, then wait for the females to mate with them.
Second interesting fact: The male’s sperm is long-lasting and can continually fertilize eggs. And the males can mate more than once.
After mating, the search for blood commences for the females, who need the nourishment to lay their eggs. Targets can be any warm-blooded animal, although the type of Minimus mosquito living in Cambodia prefers humans. Once full, they wait two or three days and then lay their eggs.
Minimus prefer shaded, slow-moving streams, while Dairus opt for stagnant waters.
The Dairus’ need for humidity means it thrives during the rainy season.
For Minimus, the pre- and post-monsoon seasons are best, meaning malaria mosquitoes are present year-round.
Third interesting fact: 2.7 percent of Minimus mosquitoes carry the malaria virus, compared to 10.7 percent of Dairus mosquitoes.
Minimus bites hardest around 9 pm or 10 pm. Dairus prefers midnight feeds. Both, however, bite all night, from around 9 pm to 3 am.
Now that the study is complete, the National Malaria Center will begin forming a formal strategy to protect those most at risk in the forested areas, Duong Socheat said. The national strategy would be completed by March, he said.
