The Oxitec laboratory located in Campinas, 100km from Sao Paulo, is producing genetically modified mosquitoes Aedes Egypti to combat Zika virus. The laboratory is acting in Piracicaba who had a dengue outbreak last summer with 132 cases and after treatment showed only two cases this summer on February 11, 2016 in Campinas, Brazil. Campinas Daily are released 250,000 genetically modified mosquitoes in two neighborhoods with a large concentration of incident cases of egypti aedes mosquito. These mosquitoes compete with wild mosquitoes and win the battle because they were outnumbered. After the breeding season, the natural females lay eggs that are not genetically modified Zika virus transmitters.