Even though their methods of infection are different, both Dengue and Malaria are transmitted through mosquitoes: the first one is transmitted by several species from the Aedes genus, while Malaria is transmitted through female Anopheles mosquitoes.
None of these diseases has a vaccine yet, even though there is research being done aiming to developed them. Without a vaccine, the avoidance of Dengue and Malaria is centered around prevention. But new techniques, using genetic engineering, have recently arisen as a promising way of stave off these diseases.
These techniques were under the spotlight on the 8th Advanced Seminar in Tropical Diseases and Vector Control, held in the end of November in Manaus, Brazil. This Seminar had the goal of disclosing and discussing new techniques applied in diseases and biological control, with a special focus on Dengue and Malaria. Osvaldo Marinotti, a researcher from the University of California (USA), noted that, even though Science already has several mechanisms to control vector mosquitoes, it still has not been able to eliminate for good the transmission of such diseases.
Inside the lab, researchers have managed to produce mosquitoes which are unable to transmit Dengue and/or Malaria. The big question is now how to "replace" these mosquitoes with the ones occurring in the Nature or, as an alternative, how to insert the genes from the "lab mosquitoes" to the wild ones.
In order to achieve the second alternative, the University of California is developing a technique called "synthetic transposon". Generically, a transposon is a DNA sequence with the ability of changing its position within the genome. Theoretically, with this technique, researches could release mosquitoes carrying the gene(s) of interest (this is, the gene or genes responsible for the lack of ability to transmit diseases) and, eventually, after a given number of crossings and generations, the gene(s) would be established in that population, eradicating the gene(s) allowing for disease transmission.
This technique is still under development and, for now, it is only put to work inside the lab and it should be a while until it is in fact applied, also because the this technique raises some ethical questions and might cause environmental impacts, both of which need further discussion. However, if successful, this technique could be one of the least harmful (for the mosquitoes) available so far, since the other techniques are related with insecticides and reduction of the populations. Basically, this technique does no harm to the mosquitoes, it simply disables their ability to transmit diseases.
P.S.: "Vector" is any agent (person, animal or microorganism) that carries and transmits an infectious pathogen into another living organism. A "vector mosquito" is a mosquito with such ability.