The World Mosquito Program: eliminating mosquito-borne diseases

The World Mosquito Program: eliminating mosquito-borne diseases
© Paulus Enggal/Eliminate Dengue Yogyakarta

The World Mosquito Program is an indispensable tool in the global effort to eliminate infectious diseases. Scott O’Neill tells Health Europa more.

What if we could eliminate diseases like Zika, dengue and chikunguya not by killing mosquitoes but by releasing them into the environment? This is the premise of the not-for-profit initiative the World Mosquito Program, which uses safe and naturally occurring bacteria called Wolbachia to protect communities from mosquito-borne diseases.

Masterminded in Australia by researchers at Monash University, the World Mosquito Program is today active in 12 countries around the world, with its unique approach having already halted dengue outbreaks in the once-vulnerable northern Australian city of Townsville. Now, researchers are hopeful that it can successfully take on other diseases like Mayaro and yellow fever, as well.

Here, Monash professor and director of the World Mosquito Program Scott O’Neill takes Health Europa through the achievements of the program to date and looks ahead to future rollouts.

Can you explain the background behind the Wolbachia method used by the World Mosquito Program? What are its main advantages?

Some groups are using Wolbachia to try and suppress mosquito populations, which they do by releasing Wolbachia-carrying male mosquitoes. What we’re doing is different. We’re not trying to suppress the mosquito population or kill it – not because there’s any particular reason that we don’t want to, but because nobody’s been able to effectively kill enough of them to stop these diseases. Instead, we’re utilising two features of Wolbachia which make it very attractive in our eyes:

  1. Wolbachia is able to invade insect populations by itself and then maintain itself in
    those populations
  2. If mosquitoes contain Wolbachia in their bodies, then the viruses that cause disease are less able to grow in the mosquitoes and therefore can’t be transmitted to people.
    Putting these two things together, we can put Wolbachia into mosquitoes and then have that Wolbachia establish itself into the wild mosquito population, preventing virus transmission.

The World Mosquito Program has expanded into 11 other countries since its launch in Australia – what results have you seen so far?

What we’ve found is that in all of the places where Wolbachia has been established, we don’t see any transmission or virtually zero transmission of these viruses. A good example of that was the paper we published on Gates Open Research earlier this year on Townsville, which has seen no local transmission of dengue for the four seasons since Wolbachia was deployed. During the 13 years prior, there was dengue transmission every year in that city.
The results suggest a very significant impact, but we still have certain experiments underway; for example, in Indonesia we are running a large randomised controlled trial to measure the exact amount of disease reduction you get from this approach. We won’t see the data from that for another 18 months or so, but we expect that it’s going to show strong disease reduction also. So, the evidence suggests that the approach is working well.

What challenges have you encountered during the rollout of the program?

In terms of the challenges we’ve faced, this approach is a little bit disruptive in the sense that it’s the opposite of what people have traditionally been taught. Instead of killing mosquitoes, we’re releasing them into the environment. When we started, we were a little bit concerned about public perception and whether or not this technology would be accepted, so we put a lot of effort into explaining what we are doing and why to the communities and governments where we work. Thankfully what we’ve found so far is that communities are able to understand and accept it, and are actually really supportive of what we’re doing. In Townsville, for example, we actually had the community undertake the releases for us.

The challenge now for us and other people doing related types of work is how to deploy at a very large scale. At the moment we’re doing work in South American cities like Rio de Janeiro, Brazil, and Medellín, Colombia, where we are deploying over cities or population centres of one to two million people and working out how to do that. A series of challenges exist around how to scale up the production and distribution of mosquitoes that are required while at the same time keeping the community informed of what’s happening.

The final issue moving forwards relates to cost-effectiveness. An independent economic analysis suggests that in many locations where populations are very dense, such as cities, it should be cost-saving for governments to deploy this technology – that is, the costs averted through prevention of disease are likely to be much greater than the costs of deployment. The challenge now is whether or not we can reduce the cost of the intervention even further, to less than US$1 (~€0.90) per person protected. If we can achieve that, then we should be cost-saving in most areas where dengue is a problem and that in turn will make deployment a much simpler task for the program.

Do you have any knowledge or is it a case of wait and see as to whether this method works long term or whether the effect might wane?

This is hard to predict. Wolbachia has been deployed in northern Australia for more than seven years now and seems to have lost none of its effectiveness during that time, which is very promising. If there is going to be any attenuation, it doesn’t look like it will happen particularly quickly. Ultimately, we will need to just monitor and wait and see, but we expect the method to remain effective at least for decades to come.

The World Mosquito Program has recently been awarded A$50m (~€32m) by the Bill & Melinda Gates Foundation and the Wellcome Trust – how will this be used to take your work further? What are your hopes for the future of the program?

The award is less about our deployments in different cities, which are funded through different mechanisms, and more about our whole core operation. What we want to do with that money is really plan for a future in which there is a high demand for this intervention, so right now we’re focused on putting the structures in place to be able to manage that future rollout. To that end, we are establishing a regional hub in Vietnam to support our projects in Asia, and we’re about to set up another regional hub in Panama, to support our work in South America.

We also want to start pilot projects in a number of countries in order to be able to pass the technology on to governments and places it can be useful, so we’re beginning to increase the number of countries we work with.

Finally, we hope to put the money towards driving down the cost of the intervention to less than a dollar per person protected.

Professor Scott O’Neill
World Mosquito Program
Tweet @wmpglobal

This article will appear in issue 8 of Health Europa Quarterly, which will be published in February 2019.

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