Monday, July 16, 2012
Genetically Modified Mosquitoes Carry A Lethal Gene Against The Dengue Virus
Brazilian health authorities have taken the lead in the fight against dengue fever not with vaccines but rather with mosquitoes. At the start of this week they expanded their program and opened a large-scale mosquito farm in the northeast state of Bahia.
Now, these are not the garden-variety mosquitoes, they are an army of genetically modified male mosquitoes being used to combat, rather than spread, disease. In the laboratory, male mosquitoes are genetically modified to carry a lethal gene against the dengue virus. They are then released into the wild to mate with female mosquitoes (who are actually the ones who bite humans since they need the blood for their eggs) and once the lethal gene is passed on to the offspring they die in the larvae stage and never make it to adulthood.
The target is dengue fever, for which there currently is no vaccine, and prevention largely has failed.
The World Health Organization classifies dengue as a mosquito-borne viral infection that causes a severe flu-like illness and sometimes a potentially lethal complication called hemorrhagic dengue. Though data from the U.S. Centers for Disease Control and Prevention report transmission in the continental United States is mostly due to travel to sub-tropical and tropical areas in the world, data from WHO indicate the incidence of dengue has increased 30 fold over the last 50 years.
According to the latest World Health Organization statistics 50 million to 100 million infections are now estimated to occur annually in over 100 endemic countries, putting almost half of the world’s population at risk.
In Brazil this year alone, the health ministry recorded 431,194 infections, with Rio de Janeiro leading in the number of cases. While the government of Brazil has attempted many other campaigns against the mosquitoes, Brazilian Health Minister Alexandre Padilha insists this new effort could be the answer to controlling the dengue epidemic in the country.
The farm in Bahia is a partnership between the Brazilian government and Moscamed, an agency that specializes in the production of transgenic insects for the biological control of pests. It uses research and methods developed by several Brazilian universities as well as by British company Oxitec. It will produce at maximum capacity around 4 million sterile males of the dengue-carrying mosquito Aedes Aegyptis per week.
Moscamed’s fact sheet on the project claims that since its beginning in February 2011 it has released more than 10 million male transgenics. This month over 95% of the larvae found in the two neighborhoods that served as test communities are already transgenic, or genetically modified to not reach adulthood, the agency says.
Though there is a lot of buzz about this alternative method of disease management, public health officials and environmentalists are skeptical and concerned about the long-term ramifications this could have. In a recent ongoing case in Key West, Florida, Oxitec was set to test a similar project in a 36-square-acre block near the Key West Cemetery. Officials of the Florida Keys Environmental Coalition sent Florida Gov. Rick Scott a letter detailing how they did not want to become “guinea pigs.”
“Despite the grave and growing public concerns that have been raised about the genetically engineered mosquitoes, there is no indication that the U.S. Food & Drug Administration or any other federal or state agency has evaluated the safety of the company’s planned release. Nor has there been an independent analysis to examine the public health or environmental impacts of this release,” the letter said.
In Brazil, Moscamed held talks with locals before the trial started. The agency also printed fliers explaining the process and sent representatives to schools to talk to the children. Dengue is a well-known fact in Brazil and so are the campaigns against it. Social media, television, day-to-day talk and such are dominated by anti-dengue slogans and campaigns launched by the government.
Scientists in Brazil are largely overseen by multiple government ministries and committees and, according to local media, residents in the areas were the trials are held are accustomed to the sights. Most of the interest comes from scientists and researchers worldwide who flock to Moscamed to learn about the benefits of the program.
According to a release by the state of Bahia, the project, paid for with funds from the state and federal government, cost about $1.6 million, and aims to control disease transmission. The state and federal governments also spend millions of dollars each year in campaigns to educate residents and to slow the procreation of mosquitoes. Brazilian researchers also work with the French Pasteur Institute in the development and trial of a vaccine against the virus.
"We will work to bring this technology to municipalities with higher levels of infestation, such as Jacobina and Itabuna, where it will be possible to analyze also in appropriate circumstances. Remember that we are still in research stage and are not routinely using the technique," said the state health secretary, Jorge Solla, in a press release announcing the new facility. After the testing phase, Solla says the project will be expanded.
Oxitec is also conducting testing in other countries. Its strand of the OX513A mosquito has regulatory approvals for import and contained (in lab) testing in Brazil, the Cayman Islands, France, India, Malaysia, Singapore, Thailand, the United States and Vietnam. Open field trials have taken place in both Grand Cayman and Malaysia, in a small scale.
Though all this may seem like a scene straight out of a science fiction movie, these genetically modified mosquitoes provide a window of hope for millions of people. The Brazilian health minister, Alexandre Padilha, said during the inauguration of the new facility that the Brazilian government will keep a close eye in this project, as well as the continued research into other avenues, and could use it as one more weapon in the fight against the disease.