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New weapon in malaria battle: mosquitoes resistant to disease

By Catholic Online (NEWS CONSORTIUM)
May 10th, 2013
Catholic Online (www.catholic.org)

Malaria, still a virulent problem in Southeast Asia and much of Africa, poses a threat to the populations there and abroad. Now, there is new hope on the horizon for battling the mosquito-borne illness: making mosquitoes resistant to the malaria-carrying parasite. While previous efforts have sought to make humans immune to the disease, to make the mosquito that carries the disease immune to malaria would halt the progress of the disease in its tracks.

LOS ANGELES, CA (Catholic Online) - As malaria is spread between people by the insects, it's hoped that giving mosquitoes malaria immunity could reduce human cases.

Experts said this was a first, distant prospect for malaria control. The World Health Organization estimates that 220 million people are infected annually and 660,000 die.

Studying the Wolbachia bacterium, which commonly infects insects, scientists at Michigan State University noted that the disease passes only from females to their offspring. In some insects, the bug is exceptionally good at manipulating insects to boost the number of females for its own ends.

Wolbachia kills male embryos in some butterflies and ladybirds. It can also produce males that can breed only with infected females, and even allows some female wasps to give birth without mating.

Malaria-carrying Anopheles mosquitoes are not naturally plagued by Wolbachia. Laboratory studies proved that temporary infection made the insects immune to the malaria parasite.

The goal was to turn a temporary infection into one that would be passed on. Researchers found a strain of Wolbachia that could persist in one species of mosquito, Anopheles stephensi, for the entire length of the study - 34 generations.

Additional research in Australia has shown that a different strain of Wolbachia can prevent the spread of dengue fever by mosquitoes.

Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases said this study was a proof of concept that the same could be done for malaria.

"If you can get it to survive and proliferate in the environment of mosquitoes in malaria-stricken areas, this could conceivably have an important impact on the control of malaria.

"I think the potential for this is very important. The implementation will be the challenge."

Commenting on the study, Prof David Conway, of the London School of Hygiene & Tropical Medicine, said: "It is interesting and is the first report of Wolbachia clearly replicating, but a number of things took away the punch."

Conway says that infected females produced fewer eggs than uninfected females, which meant the infection would struggle to spread in the real world.

He cautioned that it was in just one species, Anopheles stephensi, which carries malaria in the Middle East and South Asia. Anopheles gambiae, in Africa, he says is an even bigger problem.

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