Residents in Yogyakarta Fight Dengue by Releasing Mosquitoes into Neighbourhood
An innovative method is helping eradicate dengue and save thousands of lives.
On a sunny Wednesday afternoon in August 2016, a group of neighbours in Tegalrejo sub-district of the city of Yogyakarta stopped what they were doing and gathered outside to talk, buzzing with excitement. While chattering among themselves, their eyes were fixed on several people in green shirts walking around the neighbourhood, each carrying small cylindrical plastic containers about 20cm in diameter. The uniformed people were sizing up the area around each house before placing the plastic containers strategically on the patios. The homeowners were looking at the containers rather excitedly, having previously heard that inside were unlikely weapons that would help fend off dengue in their community. Acknowledging that dengue has become a serious health threat in their neighbourhood in recent years, they agreed to volunteer to host the tiny weapons in their houses. Inside each container were 100 mosquito eggs. Wait, what?
It sounds counter-intuitive, but these eggs are not from ordinary mosquitoes. Eliminate Dengue Indonesia, a research program based in the Faculty of Medicine at the University of Gadjah Mada in Yogyakarta, breeds these mosquitoes carrying a bacterium called Wolbachia in their cells. Although Wolbachia is naturally present in up to 60 percent of all the different species of insects, it is not found in the Aedes aegypti mosquito, the primary species responsible for transmitting human viruses such as dengue, chikungunya and Zika. When introduced into the Aedes aegypti mosquito, Wolbachia inhibits these viruses from growing inside the mosquito and being transmitted to humans.
Eliminate Dengue Indonesia is part of the Eliminate Dengue Program, an international research collaboration led by Professor Scott O’Neill of Monash University in Australia. The collaboration takes a different approach to other research projects that use Wolbachia to control mosquito-borne diseases. Instead of releasing only adult male Wolbachia mosquitoes to a neighbourhood, the project runs a method called ‘Rear and Release’. Professor Adi Utarini who heads the program in Yogyakarta explained, “We don’t seek to eliminate all populations of wild mosquitoes, we aim to spread Wolbachia into wild mosquito populations to reduce their ability to transmit dengue.”
“We are distributing male and female mosquito eggs that have been infected with Wolbachia to a neighbourhood. After the eggs hatch, they will fly out and mate with the wild mosquitoes,” she said.
“If a Wolbachia-infected male mosquito mates with an uninfected female, those eggs won’t hatch. If mating occurs with an infected female, normal offspring with Wolbachia will be produced and the bacteria are passed on from generation to generation.
“Over time, the percentage of mosquitoes carrying Wolbachia grows until it remains high, even without any further releases. Mosquitoes with Wolbachia are less able to transmit viruses to people, so there’s much less risk of dengue outbreaks in those areas.”
On that sunny afternoon in August, Eliminate Dengue Indonesia made the initial run to distribute mosquito eggs in purpose-built mosquito release containers to be placed outside homes in Tegalrejo and six other sub-districts in Yogyakarta. They plan to distribute a total of 6,000 containers to 1,600 houses in the sub-district by mid-2017, following successful trials conducted on a smaller scale in the neighbouring towns of Sleman and Bantul in 2014 and 2015. In those previous trials, the population of Wolbachia mosquitoes rose to between 85 and 90 percent eight months to one year after release, resulting in a significant reduction of dengue cases in those two areas.
The biggest challenge of this project turned out to be a non-technical one. How do you convince people that having a bucket filled with Aedes mosquito eggs around their house will eventually reduce the chance of getting dengue? It is so contrary to what they have always known: Aedes mosquitoes transmit dengue. The Eliminate Dengue program carefully spent the first two years of its project gaining public trust, educating residents about Wolbachia and ultimately winning approval for rearing and releasing Wolbachia mosquitoes in and around their houses.
“We held meetings to educate the community on dengue-related subjects,” Professor Adi Utarini said. “We formed community referral groups to discuss key issues and we adopted a ‘seeing is believing’ principle. We invited community members to visit our insectary and diagnostic laboratory to better understand Aedes mosquitoes and Wolbachia,” she added. “We used various communication channels such as face-to-face talks, short text messages, telephone and email to capture any community concerns, opinions and complaints every day. We then developed protocols to address these concerns.”
The efforts yielded 95 percent individual consent by residents in the first trials in Sleman. Having learned from these first trials, the project improved the approach and eventually gained 100 percent community consent in the second trials in Bantul. The program, which earlier also gained approval and strong support from both city and provincial governments, continued to conduct community engagement activities even after the release. These included school visits where children learned about dengue and Wolbachia, a media day where journalists had a chance to donate their blood for mosquitoes’ food, and participation in local events to increase public interest in eliminating dengue.
Dengue remains a serious health risk for Indonesia, where its location in the tropics coupled with increasingly larger urbanized areas provides an ideal habitat for Aedes aegypti mosquitoes. Despite continuous efforts to control dengue by the Indonesian Government and many civil society organizations, dengue rates have been increasing every year since 1968 when the first case was reported. According to the Ministry of Health, 126,675 cases of dengue were clinically reported nation-wide in 2015 resulting in 1,229 fatalities, although the real number could be much higher due to unreported cases. In Yogyakarta, this year alone, 1,136 cases were reported up to September, already exceeding last year’s total of 945. This means more than one in every 700 residents in Yogyakarta suffers from dengue infection every year, causing a significant burden on the medical system as well the loss of productive days. The urgency of dengue control in Indonesia cannot be overstated.
Reducing dengue in Indonesia using Wolbachia has many advantages over conventional methods that use insecticides. It is much more cost-effective and sustainable, as it does not try to reduce the overall number of mosquitoes. Insecticides are not environmentally sustainable and are often ineffective and expensive due to the need to reapply. Having visited the program and been impressed with the initial results of the first two trials, Mohammad Nasir, the Indonesian Minister of Research, Technology and Higher Education, stated his support to expand the program nationally if the Yogyakarta trials were successful.
Currently, Eliminate Dengue Indonesia is fully-funded by the Tahija Foundation, an Indonesian philanthropic organisation. Dr Sjakon Tahija, one of the founders and trustee board members of the Tahija Foundation, said his foundation previously supported various dengue eradication initiatives with varying degrees of success, and none had been sustainable in the long term. Having fully supported the Eliminate Dengue Indonesia program from the beginning, Dr Tahija proudly stated during a ceremony in August to mark the release of Wolbachia mosquitoes in Yogyakarta:
“We are pioneers in the world, as no one can conduct this project on such a large scale as in Indonesia. We believe we could do something to better mankind, and improve scientific research in Indonesia.”
The staff at Eliminate Dengue Indonesia and the residents in Tegalrejo, Yogyakarta, could not agree more.
