By Alyah Khan

Brazil’s health ministry recently announced its plan to breed genetically modified mosquitoes to stop the spread of dengue fever. According to news reports, scientists are focusing intensely on mosquito control because there is currently no vaccine to protect against dengue.
Dengue is caused by one of four related, but distinct, virus serotypes, which are transmitted to humans by the Aedes aegypti mosquito. The disease is characterized by headache, skin rash and debilitating muscle and joint pains. The World Health Organization estimates that there may be 50 to 100 million dengue infections worldwide every year. (More information on the disease can be found here.)
In Brazil, there have been nearly 500,000 dengue cases registered this year.
A report by Agence France-Presse said that the initiative in Brazil “will produce large quantities of genetically modified male Aedes aegypti mosquitoes, which will be released into nature to mate with females.”
The experiment has already been attempted in two mosquito-infested towns in the country and was able to reduce the mosquito population by 90 percent in six months, Brazil’s health ministry said.
Further, health officials explained that mosquitoes bred in the so-called “mosquito factory” receive injections of different viruses, “which are transmitted in the instant of reproduction and kill the larvae before they are born, which means the number of mosquitoes tend to diminish.”
A related report published this month in the New Yorker recounts how the British biotechnology company Oxitec has “developed a method to modify the genetic structure of the male Aedes mosquito, essentially transforming it into a mutant capable of destroying its own species.” Oxitec is collaborating with Moscamed and the University of São Paulo on a field trial that began about a year ago.
The effectiveness of these efforts in combating dengue remains to be seen. We will look more at the use of genetically modified mosquitoes to control dengue in an upcoming blog post, which will include examining what advocates and critics of this approach say.
Meanwhile, substantial progress towards finding a dengue vaccine has been made in the last decade. Several vaccines are in various stages of advanced developed, with clinical trials underway on five candidate vaccines. (More information on vaccine development can be found here.)