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Infection Makes Mosquitoes Immune to Malaria Parasites

Researchers established a bacterial infection in mosquitoes that helps fight the parasites that cause malaria. The infected insects could be a significant tool for malaria control.

Malaria is caused by a single-cell parasite called Plasmodium. The parasite infects female mosquitoes when they feed on the blood of an infected person. Once in the mosquito’s midgut, the parasites multiply and migrate to the salivary glands, ready to infect a new person when the mosquito next bites. Wolbachia is a naturally occurring bacterium that was previously found to block development of Plasmodium parasites in mosquitoes. Wolbachia can be transmitted by an infected female insect to her offspring. Uninfected females that mate with infected males rarely produce viable eggs—a reproductive dead end that gives infected females a reproductive advantage and helps the bacteria spread quickly. Wolbachia were successfully used in a field trial to control dengue, another mosquito-borne disease. However, the bacteria don’t pass consistently from a mother to her offspring in Anopheles mosquitoes, which spread malaria.

A team led by Dr. Zhiyong Xi at Michigan State University set out to establish a stable, inherited Wolbachia infection that could block Plasmodium growth in Anopheles. They focused on Anopheles stephensi, the primary malaria carrier in the Middle East and South Asia.

Funding: NIH’s National Institute of Allergy and Infectious Diseases (NIAID) and the Bill and Melinda Gates Foundation.

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