A new breed of mosquito could become a key ally in the fight against dengue fever. An infectious tropical disease caused by the dengue virus, dengue fever is principally transmitted by the Aedes aegypti mosquito. Currently there is no vaccine for the disease and regions where the disease is endemic are left struggling to prevent infection by reducing mosquito habitat, decreasing the number of mosquitoes and limiting human exposure to being bitten.
But recently the leading scientific journal Nature published two papers describing the results of biological control field trials where wild mosquito populations were genetically manipulated to suppress dengue virus transmission. The results are the work of the Eliminate Dengue program, an international collaboration of scientists located in Australia, Vietnam, Thailand, the U.S. and Brazil. The program’s aim is to stop the Aedes aegypti mosquito from passing dengue virus between humans by introducing a naturally occurring bacterium called Wolbachia into the existing wild mosquito population.
The papers describe how researchers successfully established Wolbachia strains within the dengue mosquito in the laboratory. Mosquitoes with Wolbachia were shown to be less likely to transmit dengue. These mosquitoes were also able to pass this trait on to their offspring. In subsequent field testing in early 2011, mosquitoes carrying Wolbachia were released in Cairns, Australia. Within a three-month period Wolbachia had successfully invaded the local mosquito populations. According to the lead researcher, Professor Scott O’Neill, “These findings tell us that Wolbachia-based strategies are practical to implement and might hold the key to a new sustainable approach to dengue control.”
Further trials will continue in Australia, as well as field releases in Vietnam, Thailand, Indonesia and Brazil where dengue fever is endemic and researchers can determine if the method is effective in reducing dengue disease in humans. If successful, the Eliminate Dengue program has the potential to benefit about 40 percent of the world’s population currently living in dengue transmission areas.
Endemic in more than 110 countries, dengue infects 50 to 100 million people worldwide a year, leading to half a million hospitalizations and approximately 12,500–25,000 deaths. The World Health Organization ranks dengue fever as the most important mosquito-borne viral disease in the world, with an estimated 2.5 billion people living in dengue transmission areas and at risk of the disease. Symptoms include fever, headache, muscle and joint pains and a characteristic skin rash. In a small proportion of cases the disease develops into the life-threatening dengue hemorrhagic fever, which mostly affects children, or into dengue shock syndrome.
FHI 360 is part of the Eliminate Dengue international team and is working in Thailand and Vietnam to gain the necessary regulatory approvals for the field releases as well as conducting community-preparedness and stakeholder engagement activities in readiness for the field releases in the near future.
Learn more at www.eliminatedengue.com.