- We piloted a project that used guppy fish in household water jars to consume the larvae of the mosquito that transmits dengue fever.
- This biological intervention was backed up by community education and communications on how to use the guppy fish to prevent the spread of dengue.
- The use of guppy fish showed in a 80% potential reduction in dengue in Lao PDR & Cambodia.
- The pilot results have been published by WHO and ADB.
It is estimated that 80% of mosquito breeding in Cambodia, Lao PDR and the Philippines occurs in domestic water jars and water storage containers with the remaining 20% taking place in accumulated water within discarded waste.
Within communities there is limited understanding of the dengue mosquito and its behaviour. Non-biological controls such as the application of chemicals during outbreaks are short-lived with mosquito larvae levels going back up after only a few weeks.
Past studies have shown guppy fish to be effective in mosquito control, but the use of fish as a core component of a population-based dengue vector control strategy had not been fully explored. The Asian Development Bank, in partnership with the World Health Organization, contracted us to test the theory.
We supported Cambodia and Lao PDR to pilot a community mobilisation approach aimed at decreasing dengue risk over two years. The objective was to build capacity for reducing mosquito breeding grounds using a behaviour change and a biological control – the guppy fish. Guppies placed into water pots and jars would consume the larvae in the water meaning that they could not develop into adult mosquitoes that transmit the disease.
We designed and piloted studies that targeted over 6,000 households across Lao PDR and Cambodia with community-based education on dengue and how to use guppies. The project incorporated other simple strategies for preventing mosquitoes breeding, such as discarding or turning over unused water pots. These efforts were backed by high level advocacy to support interventions, such as school drama competitions judged by the provincial governor. We also analysed the costs for introducing the approach nationwide.
An important part of the study was to determine both community acceptance of guppy fish and appropriateness of domestic water containers as a fish habitat. In Lao PDR, villagers and health workers found that using primary schools as guppy breeding and distribution centres was particularly effective and in Cambodia, the Tuk Tuk mobile education campaign was popular. Each month, two Tuk Tuks went from village to village playing the ‘dengue song’ and distributing flyers. All villages in the intervention area were visited, with each Tuk Tuk taking around four days to cover all the villages.
- At the 12-month point, one full dengue cycle, none of the target water jars in households in intervention sites had any evidence of larvae if there was at least one guppy fish. Whereas, in control sites an estimated 24% of the target water containers had larvae. Overall this suggests that an average guppy coverage rate of 80% in households (ie at least one guppy per jar) is sufficient to significantly reduce the mosquito population.
- The application of guppies in Cambodia at the time of the July 2010 dengue outbreak demonstrated that guppies can be used to control and prevent outbreaks.
- The project has validated the use of guppy fish as a low-cost, year-round vector control measure that is feasible to implement, acceptable and safe to the public, and has minimal recurring costs.