What need might gene drive-modified mosquitoes address that more conventional vector control cannot?
Conventional vector control has proven successful in reducing and in some cases eliminating vector-borne diseases. Environmental engineering (e.g., draining swamps) and insecticides (principally DDT) were important in eliminating malaria from North America and Western Europe. In Africa, insecticide-treated bed nets and indoor spraying of insecticides have substantially reduced the burden of malaria. However, insecticide-based control methods are costly, subject to development of resistance in the mosquito, and apt to miss important populations of disease-transmitting mosquitoes. Progress against malaria has plateaued in recent years, and the problem remains especially severe in Africa. Theoretical advantages of genetically modified mosquitoes are that they could do the following:
- Provide protection that benefits all people in the treated area regardless of socioeconomic status or access to healthcare facilities and without imposing additional burdens or requiring people to modify their behaviors.
- Affect only the target species directly, unlike the case with some insecticide-based methods, and thus have fewer effects on biodiversity.
- Reach mosquito populations and breeding sites that traditionally have been the hardest and most expensive to target using conventional vector control strategies, by exploiting the natural seeking behavior of the mosquitoes to find each other and oviposition sites.
- Be useful in both urban and rural environments and whether the vector is present at high or low density.
- Provide ongoing protection in situations where delivery of other malaria control tools has been disrupted.
Some gene drive technologies could be highly sustainable, requiring only a few releases of gene drive-containing mosquitoes to make large and lasting impacts on a target species. Some gene drive technologies could spread over large geographic areas that are challenging to cover using conventional technologies such as insecticides. These characteristics are expected to make their use highly cost effective. Moreover, ongoing protection provided by mosquitoes carrying self-sustaining gene drive could prevent re-introduction of a disease in regions where it has been eliminated, or protect regions from introduction of new mosquito-borne diseases.
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