Parasite controls biting behaviour of mosquitoes
a joint study by scientists from Africa and France shows mosquitoes (vector) are more attracted to people already infected with the malarial parasite, Plasmodium falciparum. This helps P falciparum orchestrate its own onward transmission from within the human body. It can manipulate the biting behaviour of the mosquito vector when it is ready for a new host.
Jacob Koella from the University of Pierre and Marie Curie in Paris and his students from University of Nairobi and the International Center of Insect Physiology and Ecology in Kenya, carried out the study in Kenya. The researchers put an uninfected child, a child in an early stage of infection and a child carrying gametocytes (advanced stage) of P falciparum in separate tents placed in a chamber. They then pumped air from the tents into another chamber housing one hundred uninfected Anopheles gambiae mosquitoes. The mosquitoes flew towards the tent that attracted them and were trapped when they entered it.
After studying 12 sets of children, the scientists found the gametocyte-infected children attracted about twice as many mosquitoes as either of the other categories. To confirm the results, the group repeated the experiment with the same children after they had been treated with anti-malarial drugs and the parasite killed. The children who had previously attracted most mosquitoes were no longer more appealing, proving that the parasite was attracting the vector. The study was published in the journal Public Library of Science Biology (Vol 3, No 9).
Malaria infects 300-500 million people annually, killing more than a million. Experts suggest this knowledge could change the way malaria is tackled. For example, the mechanism the mosquitoes are using could help develop ways to divert them away from people.
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