Brazil has authorized the use of genetically modified (GM) Aedes aegypti mosquitos in an attempt to take an important step forward in the fight against the most common transmitter of dengue fever. The disease infected 1.5 million people last year in the country, causing 545 deaths. The National Technical Commission on Biosafety, an organization run by the Ministry of Science, Technology and Innovation, approved the commercialization of the male OX513A strain of the species on April 10 with 16 votes. There was one vote against the measure.
The project involves the modification of male Aedes aegypti mosquitos to carry two additional genes that prevent the production of viable offspring. The mosquitos can breed but their offspring will die before reaching adulthood – a method that could result in a significant reduction in the Aedes aegypti population. Some organizations, however, say there is no scientific evidence to validate this thesis or evaluate the environmental risks of eradication.
British firm Oxitec will be in charge of mass producing the modified strain after three years of experiments in collaboration with Brazilian organization Moscamed. The decision of the Brazilian government is based on two trials carried out in Juazeiro, in Bahia state, where, according to researchers, the release of transgenic mosquitoes led to 81 percent and 93 percent reductions in the population of the species.
The Commission has warned that large-scale release of these insects should be accompanied by comprehensive control of the population of the other carrier-species, Aedes albopictus, “due to the risk that it may take over the ecological vacuum caused by the eradication of Aedes aegypti.” These observations are already being implemented in a third trial in Jacobina, a town of 80,000 in Bahia, where Moscamed is releasing millions of transgenic mosquitos to analyze the behavior of the Aedes albopictus. In order to guarantee a reduction in the Aedes population, researchers say there is already proof that 500 GM insects per resident will need to be released .
“As a scientist, I cannot state that there is zero risk, just as a vaccine is never 100 percent effective,” said Margareth Capurro, a molecular biologist and researcher who specializes in mosquitos. “What I can say is the project is working and the potential of this genetically modified insect is very good. It’s important to take precautions such as ensuring quality control measures in the production. We cannot release defective mosquitos on the market or allow females to escape. That would be like selling contaminated milk.”
According to the Ministry of Health, 321 cities in Brazil are at risk of suffering an epidemic and 725 others are on alert. Every year, during the rainy season that starts in March, a state of collective hysteria overtakes countless Brazilian municipalities as a result of dengue fever. The disease causes vomiting, fever and muscle fatigue and there is no known effective vaccine against it. The variant that causes hemorrhages is the most feared because it can lead to death. For now, the only preventive measures are to avoid spaces with stagnant pools of water, which become breeding grounds for Aedes aegypti; to use repellents; and to spray pesticides – an option that may present health risks.
After the green light from the Commission, which only limited itself to endorsing the safety of commercializing GM mosquitos, the National Health Surveillance Agency will have to approve the sale of the product and control its entry in the market.
Capurro assures the release of transgenic insects “does not aim to eradicate the species, but rather to reduce the population to levels that minimize the transmission of dengue fever.” She points out that in the 1950s insecticide use eradicated the species, which is originally from Singapore and arrived in Brazil aboard ships and planes, in the country, but it returned in the 1980s.
According to Oxitec CEO Hadyn Parry, “the beneficial environmental profile, coupled with excellent efficacy to date, make the Oxitec mosquito a valuable new tool for health authorities around the world to complement their existing efforts in tackling the mosquitos that spread dengue fever.”
“There is no evidence that shows the mosquito reduces the incidence of dengue fever,” says Gabriel Fernandes, a consultant for Brazilian organization AS-PTA, which supports family farming and sustainable rural development.
“Ineffective and dangerous, the transgenic Oxitec insects are a showcase for British exports to Brazil,” says Helen Wallace, director of British organization GeneWatch. “A desperate attempt to support British biotechnology and to reward venture capital investors should not blind the governments of the United Kingdom and Brazil to the risks of this technology,” she added.