Scientists around the world are currently hard at work genetically engineering new strains of mosquitoes that are poor hosts for diseases such as malaria, dengue and yellow fever, in the hopes of cutting down the spread of these germs. New research suggests, however, that although these insects might succeed in reducing the number of infections, they might also inadvertently boost the severity of remaining ones.


http://www.scientificamerican.com/article.cfm?id=transgenic-mosquitoes