GM Mosquitoes:
Manipulating a corner of the ecosystem to halt the transmission of Malaria
Above- the life cycle of a malaria parasite
Above- the life cycle of a mosquito
​Why are scientists creating GM mosquitoes to stop malaria?
Because malaria is a vector-borne disease "experts agree that the only sucessful way to control or prevent this disease is to combat its vector" (1.7). Traditional methods include the use of mosquito nets, insecticide-impregnated mosquito nets and spraying chemicals into the enviroment to kill mosquitoes, but that is not efective enough as millions of people each year are still infected or do not have access yet to these control measures. In addition, insecticide resistance is developing in some mosquito populations. To combat the mosquito, new approaches are needed, and GM mosquitoe are promising in this regard. GM mosquitoes could be released into the environment to either mix with the gene pool creating mosquitoes that are better for human health because they are resistant to the Plasmodium spp., or that carry lethal mutations, reducing the overall mosquito population.
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What do scientists hope to accomplish?
An overall reduction in transmission of Plasmodium spp. to humans, thus, less burden of illness, and far fewer deaths. The health of a developing nation is critical to climbing out of poverty -- and, malaria mainly afflicts impoverished countries.
As noted, GM mosquitoes can be used in two main ways. One way is to decrease the number of mosquitoes, so the mosquito population cannot support the transmission of the parasite. The GM mosquitos released in this case are males that are either sterile or contain a genetic modification (a lethal dominant mutation) so that offspring in the wild will not survive to adulthood.
The second approach is to genetically modify mosquitoes in various ways so they are no longer able to transmit the parasite. Please see the Timeline for examples under development.
There are concerns that with global climate change, human malaria may spread to new areas. There is not proof of that at this time; however, a malarial Plasmodium that infects birds (causing avian malaria) has been found to be tranmitted for the first time in Alaska. Researchers predict that, "the unprecedented rate of change in the Artic climate" could affect the range and impact of avian malaria (0.2). And, French researchers conducted a study that "provides evidence that with impending global warming, [avian] malaria will spread in the north of France" due to climate change (0.3).
With the evidence pointing towards climate-change induced geographic expansion of the mosquito vector of malaria, it is important to prepare. Genetically modified mosquitoes could break the vector-disease transmission cycle and halt the spread of malaria as the world warms, as well as decrease transmission in currently affected regions of the world.
Environmental Biotechnology Employed to Address a Disease Predicted to Spread with Global Climate Change.
Background
Understanding the Vector: Anopheles Mosquitoes
Three main species of the Anopheles mosquito transmit the malaria parasite to humans (Plasmodium spp.): Anopheles stephensi, Anopheles albimanus, and Anopheles gambiae (this species is the most important for malaria transmission in Africa).
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Understanding the Disease: Malaria
Malaria is caused by Plasmodium parasites which are transmited by the Anopheles mosquito. The four main species infective to humans are P. falciparum, P. vivax, P. malariae, and P. ovale.
Malaria causes symptomatic infection in over 200 million people per year, and kills approxomately 1 million people each year (the majority are children).
For more in-depth information please view the World Health Organization website.
Above- the map shows what stage countries are in as they work toward controlling and eventually eliminating malaria. The GM efforts are focusing on helping those countries.
Above- Anopheles gambiae feeding