Wolbachia are natural bacteria present in up to 60% of insect species, including some mosquitoes. However, Wolbachia is not usually found in the Aedes aegypti mosquito, the primary species responsible for transmitting human viruses such as Zika, dengue and chikungunya.
For many years, scientists have been studying Wolbachia, looking for ways to use it to potentially control the mosquitoes that transmit human viruses. The World Mosquito Program’s research has shown that when introduced into the Aedes aegypti mosquito, Wolbachia can help to reduce the transmission of these viruses to people. This important discovery has the potential to transform the fight against life-threatening mosquito-borne diseases.
Wolbachia are naturally occurring bacteria found in 60% of all insect species. Wolbachia is safe for humans, animals and the environment. Two independent risk assessments have been conducted, both of which gave an overall risk rating of ‘negligible’ (the lowest possible rating) for the release of mosquitoes with Wolbachia.
The World Mosquito Program’s Wolbachia method
The WMP's field teams release male and female Aedes aegypti mosquitoes with Wolbachia over a number of weeks. These mosquitoes then breed with the wild mosquito population. Over time, the percentage of mosquitoes carrying Wolbachia grows until it remains high without the need for further releases. Mosquitoes with Wolbachia are less able to transmit viruses to people, decreasing the risk of Zika, dengue and chikungunya outbreaks.
The WMP’s Wolbachia method helps to protect communities from mosquito-borne diseases like Zika, dengue and chikungunya, and does so without posing a risk to natural ecosystems or human health. Our method has some unique features. Unlike most other initiatives, our method is natural and self-sustaining. Our method does not suppress mosquito populations or involve genetic modification (GM) as the genetic material of the mosquito has not been altered.
Long-term monitoring shows that the WMP’s natural Wolbachia method is self-sustaining in almost all international project sites up to seven years after our teams carry out releases.
Alternative uses of Wolbachia
Wolbachia bacteria can be used in several ways, including to suppress mosquito populations. Other research may involve the release of only male mosquitoes with Wolbachia. When these mosquitoes mate with wild female mosquitoes without Wolbachia, they are unable to reproduce.
This technique requires the release of a large number of male mosquitoes to reduce the overall mosquito population. As with insecticides, this technique would need to be reapplied over time as the population of mosquitoes gradually returns.
In contrast, the World Mosquito Program's Wolbachia method is unique because it is self-sustaining and does not need to be continually reapplied, making it an affordable, self-sustaining, long-term solution. Our method reduces the ability of mosquitoes to transmit dengue, Zika and chikungunya on to people, without suppressing mosquito populations and potentially affecting ecosystems.
We are currently adapting our approach for use in large, urban environments and targeting a cost of US$1 per person.