There is news for malaria-ravaged countries, including India. Researchers at the Johns Hopkins University in Maryland, US, have developed a genetically engineered mosquito that is resistant to malaria. This finding, reported in the recent issue of the Proceedings of the National Academy of Sciences (PNAS) journal, has created a stir.

It is felt that conventional techniques to control mosquito-borne diseases like malaria, chikungunya and dengue are not going to be enough. Scientists across the world have begun working on the premise that in addition to spraying insecticides, controlling breeding sites and promoting bed-nets, genetic strategies also need to be evolved to control the entire spectrum of diseases transmitted by mosquitoes.

Genetic strategies include two methods: mosquito population replacement and population suppression. The one reported in PNAS is that of replacement. In India, there is a proposal pending with the Review Committee on Genetic Manipulation (RCGM) to import a batch of GM mosquitoes for fully-contained trials. This one works on a technology which suppresses the population of Aedes mosquitoes that carry dengue and chikungunya.

The Johns Hopkins University has worked on a replacement strategy for malaria-carriers: they have reported that the engineered mosquitoes have a higher survival rate than non-resistant ones, meaning they could eventually replace the ones that can carry the disease. When they fed on malaria-infected mice, the resistant mosquitoes were able to outdo the non-resistant ones. Starting with the same number of resistant and non-resistant mosquitoes, they found that after nine generations, the resistant type made up 70 per cent of the population.

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