An insect cell that contains Wolbachia

Wolbachia is found in up to 60% of all insect species including the Cairns birdwing butterfly.

Wolbachia (green) in the ovaries of Aedes aegypti mosquitoes

High magnification image of Aedes aegypti cells with Wolbachia (green)

Wolbachia is found in moths, butterflies, ladybirds and the blue damselfly (pictured).

Wolbachia

Wolbachiais a natural bacterium present in up to 60% of all the different species of insects around us, including some mosquitoes.

However, it is not usually found in the Aedes aegyptimosquito, the primary species responsible for transmitting human viruses such as dengue, chikungunya, and Zika.

For many years scientists have been studying Wolbachia, looking for ways to use it to potentially control the mosquitoes that spread human diseases.

Our research has shown that when introduced into the Aedes aegyptimosquito, Wolbachiacan stop these viruses from growing inside the mosquito and being transmitted to people. This important discovery has the potential to transform the fight against life-threatening viral diseases.

Wolbachiais safe for humans, animals and the environment. It is a naturally occurring bacterium already found in the environment in many insect species. 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.

Alternative uses of Wolbachia

Other researchers are experimenting with Wolbachiaas a means of suppressing Aedesmosquito populations. This approach involves the release of only male mosquitoes with Wolbachia. When these mosquitoes mate with wild female mosquitoes without Wolbachia, they are unable to reproduce. The 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 to this approach, the Eliminate Dengue program is not trying to reduce the overall number of mosquitoes. Our aim is to spread Wolbachiainto wild mosquito populations to reduce the ability of these mosquitoes to transmit disease. We release a smaller number of male and female mosquitoes with Wolbachiaover a number of weeks and these mosquitoes then mate with the wild mosquito population. As the bacteria is passed on from generation to generation and over time, the percentage of mosquitoes carrying Wolbachiagrows until it remains high without any further releases. Mosquitoes with Wolbachiaare less able to transmit viruses to people, so the risk of outbreaks in those areas is reduced.
 
Our research has shown that Wolbachiacan sustain itself in mosquito populations without continual reapplication, which makes this method sustainable and cost-effective in the long-term. We are currently adapting our approach for use in large, urban environments and targeting a cost of US$1 per person. 
 
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