Abstract
BackgroundIn the Mexican state of Guerrero, some households place fish in water storage containers to prevent the development of mosquito larvae. Studies have shown that larvivorous fish reduce larva count in household water containers, but there is a lack of evidence about whether the use of fish is associated with a reduction in dengue virus infection. We used data from the follow up survey of the Camino Verde cluster randomised controlled trial of community mobilisation to reduce dengue risk to study this association.MethodsThe survey in 2012, among 90 clusters in the three coastal regions of Guerrero State, included a questionnaire to 10,864 households about socio-demographic factors and self-reported cases of dengue illness in the previous year. Paired saliva samples provided serological evidence of recent dengue infection among 4856 children aged 3–9 years. An entomological survey in the same households looked for larvae and pupae of Aedes aegypti and recorded presence of fish and temephos in water containers. We examined associations with the two outcomes of recent dengue infection and reported dengue illness in bivariate analysis and then multivariate analysis using generalized linear mixed modelling.ResultsSome 17% (1730/10,111) of households had fish in their water containers. The presence of fish was associated with lower levels of recent dengue virus infection in children aged 3–9 years (OR 0.64; 95% CI 0.45–0.91), as was living in a rural area (OR 0.57; 95% CI 0.45–0.71), and being aged 3–5 years (OR 0.65; 95% CI 0.51–0.83). Factors associated with lower likelihood of self-reported dengue illness were: the presence of fish (OR 0.79; 95% CI 0.64–0.97), and living in a rural area (OR 0.74; 95% CI 0.65–0.84). Factors associated with higher likelihood of self-reported dengue illness were: higher education level of the household head (OR 1.28; 95% CI 1.07–1.52), living in a household with five people or less (OR 1.33; 95% CI 1.16–1.52) and household use of insecticide anti-mosquito products (OR 1.68; 95% CI 1.47–1.92).ConclusionsOur study suggests that fish in water containers may reduce the risk of dengue virus infection and dengue illness. This could be a useful part of interventions to control the Aedes aegypti vector.
Highlights
In the Mexican state of Guerrero, some households place fish in water storage containers to prevent the development of mosquito larvae
We found fish used to control the dengue vector Ae. aegypti in 17.1% (1730/10,111) of all households: 9.3% (457/4930) of households in control communities and 24.6% of households (1273/5181) in intervention communities (Figs. 1, 2 and 3)
Our study confirms that fish can be an effective community measure for dengue vector control, and extends this to show that they can be associated with a reduced risk of dengue infection and dengue fever
Summary
In the Mexican state of Guerrero, some households place fish in water storage containers to prevent the development of mosquito larvae. Studies have shown that larvivorous fish reduce larva count in household water containers, but there is a lack of evidence about whether the use of fish is associated with a reduction in dengue virus infection. In 2015, 26,665 cases of dengue fever were reported in Mexico alone. As early as the 1930s, as part of a successful battle against yellow fever in southern North America, people placed fish belonging to the Gambusia genus in rain water-collecting cisterns in Key West, Florida, to control the Aedes aegypti mosquito [4]. In 1987, after an outbreak of dengue, Wu et al introduced fish in household water containers in China and found a significant reduction in indices of larval infestation [5]. Others have shown the survival of fish in household containers can be adequate with proper care [10]
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