1. How does your approach compare to other solutions in development?
There are several different approaches to reducing the transmission of diseases spread by Aedes aegypti, which are at various stages of development around the world. One of these is developing vaccines, which continues to be explored by a number of research groups and organisations around the world.
Further methods include new insecticides and new methods of applying existing insecticides. There are also groups exploring ways to genetically modify mosquitoes to control their breeding and reduce the mosquito population.
Other researchers are experimenting with Wolbachia as a means of suppressing Aedes mosquito populations. This method 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 to many of these approaches, the World Mosquito Program is not trying to reduce the overall number of mosquitoes. Our aim is to introduce Wolbachia into wild mosquito populations to boost the number of Wolbachia carrying mosquitoes and reduce their ability to transmit diseases. Our method does not involve genetic modification (GM), as the genetic material of the mosquito has not been altered.
Following further efficacy reporting, we expect our approach will be shown to be particularly effective in large urban areas where conventional approaches – such as spraying insecticides – are often ineffective and expensive. The World Mosquito Program’s approach is compatible with existing control methods, including vaccines.
2. You say that the World Mosquito Program's Wolbachia method will be more economical and sustainable than other methods. Why is that?
The World Mosquito Program (WMP) is implementing a self-sustaining, cost-effective form of vector control, without needing to continually suppress the mosquito population. In contrast to insecticide based programs, or the use of Wolbachia for population suppression, our program's method offers sustained protection from disease regardless of the number of mosquitoes present in the environment.
The WMP is not trying to reduce the overall number of mosquitoes, instead we aim to boost the number of Wolbachia carrying mosquitoes to reduce their ability to transmit diseases. We release a smaller number of male and female mosquitoes with Wolbachia over a number of weeks and these mosquitoes then mate with the wild mosquito population. The bacteria is passed from generation to generation, and over time, the percentage of mosquitoes carrying Wolbachia grows until it remains high without need for further releases. Mosquitoes with Wolbachia are less able to transmit viruses to people, so the risk of outbreaks in those areas is reduced.
The World Mosquito Program’s research has shown that Wolbachia can sustain itself in mosquito populations without continual reapplication, making this a long-term, cost-effective and self-sustaining approach. We are currently adapting our approach for use in large, urban environments and targeting a cost of US$1 per person.
3. Will this method be effective in the long-term?
It is very difficult to predict how long the Wolbachia method of control will be effective. We could imagine that over time the method might become less effective but we have no way to predict how quickly that might happen. Even if the method lasted for a number of decades then that would equate to a large benefit in the global fight to control dengue.
The possibility of effective, but transient control should not be seen as a negative attribute of this technology. Many control measures become less effective over time. For example, many insect pests have shown increasing resistance to chemical insecticides. Yet, these tools have been incredibly valuable in saving human lives from major diseases such as dengue and malaria.
4. Does your approach involve genetic modification?
The World Mosquito Program’s method is not genetic modification (GM) as the genetic material of the mosquito has not been altered. We are using naturally occuring bacteria that, when present in the Aedes aegypti mosquito, reduce its ability to pass dengue, zika and chikungunya between people. The bacteria – called Wolbachia – naturally occur in up to 60% of the insect species around us.
5. Does this approach have any effect on other pathogens or diseases transmitted by the Aedes aegypti mosquito?
Although our main focus is on reducing dengue transmission, the Wolbachia method has also been shown to reduce transmission of other viruses including Zika, chikungunya and yellow fever.