1. What is Eliminate Dengue Indonesia?
Eliminate Dengue Indonesia is a collaborative research project between the Faculty of Medicine, Gadjah Mada University (UGM), Monash University, Melbourne, Australia and Yayasan Tahija (The Tahija Foundation), Indonesia, with collaborating scientists at the University of Melbourne, Australia. The project began in September 2011 with the sole aim of developing and trialing the Wolbachia control method to reduce dengue transmission in Indonesia.
2. Where in Indonesia have you released Wolbachia mosquitoes?
Since 2014, Eliminate Dengue Yogyakarta has conducted field trials using Wolbachia in selected neighbourhoods of Sleman and Bantul. Prior to the first releases in these areas, we spent months monitoring the mosquito population and talking with community leaders and residents at the district, village and hamlet levels to gauge support for the field trial. Results from these initial trials have been very encouraging, and the project is now expanding to cover more areas of Yogyakarta.
In the second half of 2016, the project commenced an impact study across Yogyakarta city to study the effectiveness of the Wolbachia method. Over the next 2-3 years, mosquitoes with Wolbachia will be introduced in various areas, and cases of dengue will be monitored to measure the impact of the intervention.
3. What do the field trials involve?
After seeking community support and regulatory approval, a field trial involves releasing Wolbachia mosquitoes once a week for a number of months. We do this in one of two ways: we release adult mosquitoes from public areas near homes, or – with permission – we place mosquito release containers on residents’ properties. These containers hold mosquito eggs, which hatch and develop into adult Wolbachia mosquitoes then fly into the environment.
Before, during and after the releases, we use mosquito-monitoring traps to collect a sample of mosquitoes from the field trial area. We place these traps on and around people’s properties. We regularly collect mosquitoes from the traps and transfer them to our laboratory, where we test them to find out if they carry Wolbachia.
4. What is the difference between the first field trials (Kronggahan and Nogotirto) and the field trials that started in December 2014 (Singosaren and Jomblangan)?
During the field trials in Kronggahan and Nogotirto, we released adult Wolbachia mosquitoes. The mosquitoes were hatched and reared in our nearby insectary prior to being released.
In Singosaren and Jomblangan, we trialled a different release method – distributing Wolbachia mosquito eggs using mosquito release containers. With permission, we placed mosquito release containers on residents’ properties. These containers held mosquito eggs, which hatched and developed into adult Wolbachia mosquitoes then flew into the environment.
As we move towards larger-scale trials of our method, we hope that egg releases will be a more practical and economical alternative to releasing adult Wolbachia mosquitoes.
5. Have the field trials in Indonesia been successful?
The aim of the initial field trials in Kronggahan, Nogotirto, Singosaren and Jomblangan has been to observe whether Wolbachia can establish in the local mosquito populations. We have seen encouraging results in our release sites, with over 80% of mosquitoes carrying Wolbachia in Kronggahan and Nogotirto, and over 60% carrying Wolbachia in Jomblangan and Singosaren. We hope that Wolbachia will now remain at high levels in the mosquito population, which we expect will reduce the risk of local dengue transmission.
Our next goal is to show our method is effective at reducing dengue transmission. During future large-scale trials, we will assess whether communities where we are trialling our method experience lower numbers of dengue cases than other areas.
While we expect the risk of local dengue transmission to be reduced in areas with high numbers of Wolbachia mosquitoes, we remind residents to continue to protect themselves from mosquito bites as usual.
7. Do the communities support the field trials?
The communities of Kronggahan, Nogotirto, Singosaren and Jomblangan have shown strong support for our research. The project team spent many months talking with community leaders and residents at the district, village and hamlet levels to gauge support before releasing Wolbachia mosquitoes. We have made every effort to meet with community members to share information about our research and respond to any questions or concerns.
Any release of Wolbachia mosquitoes only proceeds with community support and government approval. We respect the views of community members and all residents have the option to be excluded from a trial, in which case we do not release mosquitoes at their home.
8. Do you have regulatory approval to conduct field trials in Yogyakarta?
After extensive consultation, we received approval from the Provincial Government to conduct field trials of our research method in Yogyakarta. We also received ethical clearance from the Institutional Review Board (IRB) at UGM, one of four internationally accredited ethical review boards in Indonesia.