To control dengue, the vector of transmission must be controlled which in this case is mosquitoes. As a result of previously done research, it is thought that Wolbachia bacteria could reduce the mosquitoes’ ability to spread the disease to humans. Researchers tested this technique in a city in Indonesia.
Dengue fever overview
Dengue is a mosquito-borne viral infection that causes between 110 and 400 million infections a year worldwide and spreads in urban and semi-urban areas in tropical and subtropical climates. It is caused by the DENV virus, which exists in four different serotypes, meaning that it can infect four times.
The disease has flu-like symptoms and causes severe muscle and bone pain that can worsen to death when outbreaks overwhelm hospitals. There is no drug to prevent dengue and no vaccine that specifically protects against it. However, dengue is treatable with simple treatments, and if you contract one of the four types, you are immune to it forever.
Methods of Control
Tiger mosquitoes of the Aedes aegypti species were selected and infected with Wolbachia bacteria. This bacterium does not harm the mosquito, but only occupies the same places in its body as the dengue virus. The dengue virus has a much harder time spreading and transmitting when the insect bites someone because the two compete for resources. In addition, Wolbachia is persistent and can be passed from generation to generation.
The test of a technique to control the incidence of dengue took place in Yogyakarta on the island of Java, Indonesia, and the results of the study were published in The New England Journal of Medicine. Scientists used five million Wolbachia-infected eggs to create a robust mosquito population. The city was divided into 24 zones, and the insects were released in 12 of them.
The results showed 318 cases of dengue in the untreated areas and only 67 in the treated areas, representing a 77% decrease in incidence. In addition, there was an 86% reduction in the number of people requiring hospitalization, with 102 versus 13 hospitalizations. Due to the success of the operation, mosquitoes have been released throughout the city and the project will be extended to surrounding areas with the aim of eradicating dengue fever in the region.
If the intervention were applied on a larger scale, covering major cities around the world, the impact on disease prevalence would be even greater. Once Wolbachia is established, it continues to protect populations from infection for a long time. This approach could also be applied to other mosquito-borne diseases, such as Zika, yellow fever, and chikungunya. Several studies are exploring the use of the bacterium in Brazil, China, and the United States.