SEATTLE, Washington — In the past 50 years, there has been a 30-fold increase of Dengue Fever prevalence, putting almost half of the world’s population at risk of the disease. Dengue Fever is considered an endemic in all 29 provinces in Indonesia. Scientists are working on a way to use Wolbachia bacteria to fight Dengue Fever in Indonesia.
Dengue Fever is a disease transmitted by female Aedes Aegypti mosquitoes. There are four closely-related strands of the virus that are called serotypes. Dengue is most common in warm, tropical climates as well as in poor urban areas. Epidemics of the disease tend to follow seasonal patterns and prevalence increases during or after the rainy season as a result of the growth in the mosquito population of an area causes. Air temperatures and humidity are also linked to a higher prevalence of Dengue because they impact the virus incubation period as well as the reproduction and feeding patterns of mosquito populations.
Dengue symptoms include fever, headaches, muscle and joint pain, nausea or vomiting, rashes and fatigue.
These symptoms can range from unnoticeable or mild to severe and requiring medical intervention. While there is no treatment for the infection itself, there are interventions to manage the symptoms that arise from the infection. In extreme cases, Dengue Fever can lead to death. However, in most affected countries, hospitals have reduced the fatality rate to lower than 1 percent.
Traditional methods of prevention include wearing clothes that protect exposed skin from mosquitos, using bed nets and screens on windows and using insect repellent. Control initiatives have also attempted to eliminate mosquito breeding sites with insecticide spray. This kind of vector control has been used on breeding sites before rainy seasons or in response to the growth of mosquito populations.
Prevalence of Dengue Fever in Indonesia
The infection for Dengue fever in Indonesia is very common. Indonesia has a high Dengue prevalence rate with 89 percent of those 14 years or older having been exposed. Fortunately, the Dengue mortality rate is much lower at around .0.85 percent of cases. In 2019, health officials in Indonesia reported 111,000 cases through October, which is significantly more than the 65,602 cases reported during 2018.
The World Mosquito Program aims to decrease the incidence of mosquito-borne diseases such as Dengue Fever through the use of small bacteria called “Wolbachia.” There are currently projects in 12 countries, including Indonesia, which have proven very effective. The earliest trial for this method started in 2011 in Northern Queensland, Australia. There has been a 96 percent decrease in Dengue prevalence with no outbreaks in the last five years in the area.
Wolbachia is carried naturally by 60 percent of insect species and is self–sustaining, harmless to ecosystems, natural and safe. The Aedes Aegypti mosquitoes do not naturally carry Wolbachia, so the World Mosquito Program breeds Wolbachia-carrying mosquitoes and releases them into areas with high mosquito-borne disease prevalence in partnership with local communities. The bacteria prevents the spread of viruses from one person to another through mosquito bites.
Trials in Indonesia
In Indonesia, initial trials conducted in the Sleman and Bantul districts yielded positive results. The World Mosquito program also established a site in the city of Yogyakarta, which has a high Dengue prevalence and is densely populated. This site reaches 242,665 people in an 18.441 square kilometer area. After two years of engagement with the community and approval from the provincial government, the program release Wolbachia-carrying mosquitoes in January 2014. Dengue incidence decreased by 75 percent in the area 27 months after the mosquito release.
The Wolbachia method is self-sustaining because the bacteria live in the insect’s cells and get passed down from one generation to the next. This makes it more cost-effective than methods requiring seasonal repetition such as insecticide spraying. It is also safer for humans with less of an environmental impact. This intervention could significantly impact the prevention of Dengue Fever in Indonesia. If used on a larger scale, these kinds of methods have the potential to decrease the global prevalence of Dengue Fever as well as other Aedes Aegypti mosquito-borne diseases including Zika, Chikungunya and Yellow Fever.
– Maia Cullen