#10 Genetically Modified Mosquitoes to Reduce Disease Threat


The pesky mosquito has been around for more than 100 million years, adapting to climates as diverse as the arctic and the equator. Wherever they go, no matter what the temperature, mosquitoes have been living off animal and human blood hosts the entire time, which allows the female to develop her eggs. And that nasty trait has caused major health issues the world over.

A female mosquito survives anywhere from 3 to 100 days, and in that time may lay upwards of 3,000 eggs. Once the mosquito feeds on a reptile, bird, or mammal carrying the malaria or dengue parasite, it picks it up, transferring it to the bloodstream of another victim with its next meal. Mosquito-borne diseases such as malaria, dengue, and yellow fever kill more people than any other diseases.

Best estimates are that mosquitoes transmit disease to more than 700 million people annually in Africa, South America, Central America, Mexico, and much of Asia. At least 2 million people annually die of these illnesses. More than 50 million people contract dengue fever each year. In the United States, this potentially deadly disease has reappeared in Florida after an absence of decades. West Nile virus, another mosquito-transmitted disease, is also a problem in Florida, and 27 other states also reported outbreaks of West Nile to the Centers for Disease Control in 2011.

Mosquito control is one of the major health issues of the twenty-first century. Powerful insecticides, draining of swamps, and mosquito nets have helped in some areas with prevention and control, but with no way to effectively sustain these efforts, the mosquito breeding and eating habits remain unbroken.

Researchers are now exploring new avenues to fight mosquitoes—and it starts in the laboratory where scientists manipulate the DNA of the insects. For the first time ever, limited trials were launched in 2010 with genetically modified mosquitoes in the Cayman Islands, where dengue fever is a major problem. More than three million reengineered male mosquitoes were released to mate with wild female species. Since the males were sterile, females couldn’t produce offspring, which quickly caused an estimated 80 percent drop in the mosquito population in a 40-acre area.

In an effort to control the transmission of malaria, a disease that affects more than 300 million people annually and kills almost 800,000 people every year, British and American scientists reported in the journal Nature in 2011 how genetic changes were successfully and relatively easily introduced into lab-raised mosquitoes over the span of just a few generations. In the future, it’s hoped that releasing modified mosquitoes into the wild whose genes cause female mosquitoes to die in the embryonic stage would eventually result in a major sex imbalance in the area. Another possibility is to release mosquitoes with a new genetic trait that makes it impossible for offspring to transmit malaria.

 It’s these non-toxic, low-cost, minimally-invasive, and highly effective innovations that could one day help bring about a significant reduction in the world population of disease-carrying mosquitoes.

Where Are They Now

With the fear of dengue fever (nicknamed "break bone fever") and its intense joint pain, cities in southern Florida and also in Brasilia, Brazil, are considering the use of genetically modified mosquitoes to eliminate the diseasecausing pests. More than 400,000 cases of dengue have been registered in Brazil in 2012, while no cases have been recorded in the Florida Keys in 2012. The plan to release genetically modified mosquitos in the Florida Keys to combat the spread of Dengue fever and chikungunya, both mostly non-deadly and rare diseases in the United States. While these GM mosquitos have already been released in the Cayman Islands, the still largely unknown effects of releasing genetically modified insects that have potential to bite humans is making this decision an extremely controversial one. With the 2016 outbreak of the Zika virus, genetically modified mosquitos again became popular, ultimately leading to the FDA approval of their use. The FDA’s released environmental assessment gives the greenlight for releasing modified Aedes aegypti mosquitos, known to transmit a wide variety of illnesses to humans, including chikungunya and dengue fever.

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