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  • 'Doomed' mosquitos could cut dengue infection rates


Scientists say that genetically modified (GM) mosquitoes, whose young die early in development, could provide a powerful means for combating dengue fever and other mosquito-borne diseases.

Sterile insects have been used for over 50 years to control or eliminate pests or disease-carrying insects such as the tsetse fly. But methods to produce sterilisation, such as radiation, are inefficient.

In research published in the journal BMC Biology last week (20 March), researchers genetically modified Aedes aegypti mosquitoes — which spread dengue and yellow fever virus — to carry genes that cause offspring to die either early in their development or at the later larval or pupal stages.

The researchers say that the gene causing death at the later stages of development was most effective at reducing the populations.

They mathematically modelled the impact these mosquitoes would have on a mosquito population in the wild.

The results indicated that by spreading the lethal genes, and ensuring that the offspring die before causing harm, GM mosquitoes could effectively reduce the wild mosquito population — and thus transmission of the dengue virus — in areas where the disease is prevalent.
"Controlling Aedes aegypti would help in the fight against chikungunya and yellow fever as well," says S. Vasan, a visiting research fellow at Oxford University, United Kingdom.

"With reasonable funding, this technology can also be extended to control other important [disease-carrying] mosquitoes including Aedes albopictus and Anopheles species."

Vasan told SciDev.Net that the mosquitoes have been tested at the Pasteur Institute in Paris, France.

He added that extensive testing was already taking place at the World Health Organization Collaborating Centre for Vectors in Kuala Lumpur, Malaysia, and that India's Review Committee on GM is examining a proposal to conduct small-scale trials.
Paul Reiter, head of the Insects and Infectious Disease Unit at the Pasteur Institute, welcomed the development, indicating that novel approaches are urgently required to replace traditional insecticidal approaches that have little, if any, impact on disease transmission. 

Dengue fever is endemic in more than 100 countries in Africa, the Americas, the eastern Mediterranean, southeast Asia and the western Pacific. The World Health Organization estimates there may be 50 million cases of dengue infection worldwide every year.

Link to full paper in BMC Biology

Reference: BMC Biology 5, 11 (2007) 

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