For years, dengue fever prevention in Honduras meant teaching people to fear and evade mosquitoes. However, a new strategy is emerging, challenging these long-held beliefs. Recently, residents in Tegucigalpa, Honduras, celebrated as Hector Enriquez released a jar of specially bred mosquitoes into the air. These mosquitoes were genetically modified by scientists to carry a bacterium called Wolbachia, which disrupts the transmission of dengue fever. When these mosquitoes reproduce, they pass on the bacteria to their offspring, potentially reducing the incidence of dengue fever.
This innovative approach to combating dengue fever was developed by the nonprofit World Mosquito Program over the past decade. It is currently being tested in more than a dozen countries, with the World Health Organization closely monitoring the mosquito releases in Honduras and other locations. In Honduras, where approximately 10,000 people are affected by dengue fever annually, Doctors Without Borders is partnering with the World Mosquito Program to release nearly 9 million Wolbachia-carrying mosquitoes over the next six months.
Scott O’Neill, the founder of the mosquito program, stated, “There is a desperate need for new approaches.”
Dengue fever, unlike many other infectious diseases, continues to pose a growing threat. An estimated 400 million people across 130 countries are infected with dengue each year, with approximately 40,000 deaths annually. While mortality rates are relatively low, dengue outbreaks can strain healthcare systems and disrupt daily life.
Traditional methods of preventing mosquito-borne illnesses, such as using insecticides or vaccines, have proven less effective against dengue. Aedes aegypti mosquitoes, which are the primary carriers of dengue, have developed resistance to insecticides. Additionally, dengue comes in four different forms, making it challenging to control through vaccines.
Bed nets are also less effective against Aedes aegypti mosquitoes, as they are active during the day when people are awake. Climate change and urbanization further complicate the fight against dengue, as these mosquitoes thrive in warm, humid environments and densely populated areas.
Wolbachia bacteria naturally exist in about 60% of insect species but were absent in Aedes aegypti mosquitoes. Scientists, led by Scott O’Neill, successfully transferred the bacteria from fruit flies into Aedes aegypti mosquito embryos, a breakthrough that laid the foundation for the Wolbachia-based strategy.
Since 2011, the World Mosquito Program has conducted trials impacting 11 million people across 14 countries, including Brazil, Mexico, Colombia, Fiji, and Vietnam. The results have been promising, with a 76% reduction in reported dengue cases observed in a large-scale field trial in Indonesia in 2019 following the release of Wolbachia-infected mosquitoes.
However, questions remain about the strategy’s global effectiveness and cost-efficiency. The six-month trial in Tegucigalpa alone is estimated to cost $900,000, or roughly $10 per person protected.
Scientists are still studying how Wolbachia precisely blocks viral transmission, and it remains uncertain whether the bacteria will work equally well against all dengue virus strains or if resistance could develop over time.
To support the program, a factory in Medellín, Colombia, breeds 30 million Wolbachia-carrying mosquitoes per week. These mosquitoes are bred to resemble local populations, including their resistance to insecticides. The eggs produced are later sent to release sites after confirmation that they carry Wolbachia.
Residents in Tegucigalpa are also participating in the effort, incubating mosquito eggs in their homes and then releasing the hatched mosquitoes into the environment to combat dengue.
As the battle against dengue fever continues, innovative approaches like the release of Wolbachia-carrying mosquitoes offer hope in the fight against this persistent and debilitating disease.