Dengue acquired epidemic proportions this year in Brazil. To combat it, health authorities have hired Oxitec, a biotechnology company that produces millions of genetically modified (GM) mosquitoes. The introduced gene expresses a protein which kills the carrier in about three days. The system is already being tested in Piracicaba.
Oxitec breeds mosquitoes and introduces a lethal gene in them at the embryonic stage. Seven million male mosquitoes have been released this year to combat dengue and chikungunya, diseases transmitted by Aedes aegypti. The males, which do not sting, impregnate wild females. The offspring expresses the lethal gene, which causes the death of the carrier in a period of two to four days. An analysis of larvae from the treated area reveals that 70% of them carry the lethal gene. The more transgenic males are released, the less likely are wild males to impregnate females.
Scientists and environmental activists oppose the measure, as they consider it has not been properly tested. Skeptics say that this system could be dangerous for humans and for the ecosystem. Combating epidemics by transgenic mosquitoes was tested before in Panama, Cayman Islands and Bahia, but at a much smaller scale. Furthermore, activists argue that there have been no studies of the presence of tetracycline in the area. Tetracycline is an antibiotic that keeps alive transgenic mosquitoes in the lab until their release.Although its use is in decline in Brazil, agroecology experts say it is still used by veterinarians.