Science - May 11, 2017

Infected child more attractive to malaria mosquitoes

Text:
Albert Sikkema

Children with malaria parasites in their blood are more attractive to malaria mosquitoes than children who are not going down with malaria, found Wageningen entomologist Annette Busula after research in Kenya.

Malaria research. Photo: Jetske de Boer

Busula released hundreds of mosquitoes in a room where there were two tents. In one of the tents there were children with gametocytes in their blood. A gametocyte is a malaria parasite in the transmissible stage. In the other tent there hung a dispenser with a standardized control odour. Of every 100 mosquitoes, 55 opted for the tent with children with malaria parasites in their blood, and only 10 went for the control odour. The rest of the mosquitoes did not go into either tent. When Busula repeated this experiment with children without this parasite in their blood, only 26 out of 100 mosquitoes went for the tent where the children were. Once again, 10 mosquitoes went for the control odour while most of the mosquitoes chose neither, reported Busula in the Journal of Infectious Diseases.

So children with the malaria parasite in their blood are bitten my mosquitoes more often than children without malaria, concludes research supervisor Jetske de Boer. And that has implications for the transmission of the disease. ‘If children with malaria have a greater chance of being bitten, the malaria parasite will spread faster than you would expect,’ says De Boer. She would also like to know which odour profile the gametocytes make to attract the mosquito, so that Wageningen entomologists can make an even better odour trap for malaria mosquitoes.

Busula’s study confirms the results of a Swiss study of 2005. But because of the advanced equipment, the Wageningen researchers could now measure very low levels of gametocytes as well. That produced new data too. Children whose blood contained the malaria parasite in the non-transmissible stage turned out not to be any more attractive to the mosquitoes. Moreover, Busula could demonstrate that the malaria parasite attracts the mosquito with the odour. After the children with gametocytes had been given antimalarial drugs and were then tested again three weeks later, the mosquitoes no longer had a preferences for them.

Busula receives her PhD for her study in Wageningen this month.

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