Bye Bye Dengue!
Wolbito mosquito - a cool way to prevent Dengue
The Wolbito Mosquito
- The Wolbito Mosquito carries a bacteria called Wolbachia. This is a naturally occurring bacterium found in many insect species, but not in the Aedes aegypti mosquito (the main dengue vector).
- Scientists found a way to introduce this bacteria in the Aedes aegypti mosquito in so-called mosquito factories.
- This is all part of a global initiative called the World Mosquito Program, that aims to promote the substitution of Aedes aegypti for Aedes aegypti with Wolbachia.
How does this work?
- Dengue, Zika, Chikungunya, are all viruses that need to hijack the mosquito's cellular machinery to replicate. They use the host cell's resources like lipids, nucleotides and ATP.
- Guess who also uses it? Wolbachia, which means it competes for the same resources as these viruses and makes it harder for them to replicate and be transmitted.
- Dengue is highly dependent on cholesterol-rich membranes to form its replication complexes, and Wolbachia alters cholesterol metabolism inside the cells.
- The Wolbachia infection also keeps the mosquito's innate immune system semi-activated, which increases antiviral effectors like:
- Reactive oxygen species (ROS)
- Antimicrobial peptides
- RNA interference machinery
How is the Wolbachia bacteria transmitted across generations?
- When an infected female lays eggs, Wolbachia are already present in those eggs, so all offspring will be infected.
- If an infected male mates with an uninfected female → the eggs fail to develop and die prematurely. This is called cytoplasmic incompatibility.
- If an uninfected male mates with an infected male → the eggs develop normally and all of the offspring will be infected.
- So basically, this gives infected females a huge reproductive advantage and pushes Wolbachia to spread through the whole population.
World Mosquito Program: achievements
- There are currently more than 12 countries involved in the program, including Brazil, Indonesia, Australia, Vietnam, Colombia, Mexico, Fiji, etc.
- In Brazil, the first large deployment of mosquitoes in Niterói, RJ, showed up to 69% reduction in dengue cases.
- The new “biofábrica” in Curitiba, PR, can produce up to 100 million mosquito eggs every week!!
- This program has also proven to be cost-saving in some settings when compared to the medical and economic burden of dengue.
- Once Wolbachia establishes in local Aedes aegypti populations, it persists without needing repeated releases, making it a long-term sustainable solution.
- A 2023 PLOS Neglected Tropical Diseases analysis estimated deployment costs ant ~US $4-9 per person.
- Compared with dengue treatment costs of ~US $500-1500 per hospitalized case.
- There is no significant harm done to humans by the Wolbachia bacteria.
Challenges
- In large cities, mosquitoes become resistant to insecticides and repellents, so they would have a fitness advantage in relation to the lab grown wolbito mosquitoes.
- To tackle this, scientists are breeding the wolbito mosquitoes with mosquitoes retrieved from the environment to “toughen” them up.
- Very high temperatures can reduce Wolbachia density in mosquitoes, which raises concerns about sustainability in tropical regions with extreme heat.