While most scientists are focused on creating vaccines for life threatening mosquito-borne diseases like dengue fever and malaria, British biotech firm Oxitec is taking a unique approach. They want to nip the problem in the bud or should we say larva, by killing the dengue-carrying mosquitos with the help of genetically modified laboratory versions.
The Oxford-based firm's genetically modified (GM) mosquitoes have two additional genes: one that makes a protein that causes the insect's development to break down, and the other that acts as a marker to allow researchers to track the mosquitoes in the field. Since females mosquitoes are the ones responsible for spreading the virus, they are killed once the laboratory bred insects reach the larval stage. The males are released in areas that are prone to the disease where they mate with dengue fever carrying females and produce offspring that inherit the two extra genes. One ensures that they die before reaching maturity, while the tracker provides data on the effectiveness of the program.
The GM mosquitoes that were approved for commercial use in 2010 have been previously deployed in small numbers in the Cayman Islands and Malaysia . And while the results were encouraging, large scale deployment did not take place until 2013, when the Brazilian government launched a two-year program to test their effectiveness by blanketing Jacobina, a farming town in the state of Bahia, with the largest swarm of the GM mosquitoes ever released. Within six months, the population of the dengue fever mosquitos declined by 79%!
Encouraged by the results, on April 10th, 2014, Brazil became the first country in the world to authorize the use of the GM mosquitoes, wherever necessary. Central America's Panama, which began its testing program with a swarm of 240,000 GM mosquitoes in February, may not be too far behind. With the disease starting to creep up in the U.S., the Food and Drug Administration is also considering introducing GM mosquitoes.
As is the case with any new solution, especially one as radical as this one, there is a lot of skepticism. Some believe that the mosquitoes have not been tested adequately and may pose some danger to humans, especially if a few genetically modified females manage to escape. Others like Thomas Scott, an Entomologist from University of California, Davis, think that they are just too expensive to deploy across entire countries.
But given that this disease affects over 390 million people in over 100 countries and the fact that conventional methods like fumigation and adding insecticides to water tanks to kill mosquito larvae are not working, government health officials have been left with no choice but to seek out a new solution. Advocates of the method argue that GM mosquitoes are much better for the environment because they reduce the need for chemical pesticides. They also help the eco-system, since innocent insects are not killed just because they happen to be close by.
Dengue fever is a debilitating disease that is transmitted primarily by the dengue mosquito, Aedus aegypti. People affected by it display severe-flu like symptoms which can prove fatal, if not cured in time. Oxitec decided to tackle this virus first because there are currently no vaccines or specific medications available to cure dengue fever. Also, the fact that it is transmitted by a single mosquito species made it easier to target. If successful, the company plans to create genetically modified specimens of mosquito species that are responsible for spreading the malaria and yellow fever viruses too!