Dados do Trabalho

Título

Can mosquito-disseminated pyriproxyfen help control dengue? A large-scale trial in Belo Horizonte, Brazil

Objetivo (s)

Mosquitoes transmit major human pathogens but are difficult to control. “Mosquito-disseminated pyriproxyfen” (MDPPF) is a new tactic in which mosquitoes are lured to PPF-treated “dissemination stations” and then transfer PPF particles to untreated larval habitats. While MDPPF has been shown to reduce mosquito population densities, its effects on disease transmission remain unknown. Here, we present the results of a large-scale, pragmatic, cluster-controlled trial measuring MDPPF effects on dengue transmission in Belo Horizonte, Brazil.

Material e Métodos

In Nov 2017–Dec 2019 (‘intervention period’), municipal vector-control staff deployed and serviced 2500 PPF dissemination stations in a cluster of 9 neighborhoods (‘intervention area’); we designated 9 adjacent neighborhoods as a ‘buffer area’ and the remaining 257 city neighborhoods as the ‘control area’. We used official dengue-notification records for Jan 2016–Dec 2019 (268,150 confirmed cases) and negative-binomial generalized linear mixed models (GLMMs) to estimate intervention effects on dengue incidence via a Before-After Control-Intervention (BACI) approach.

Resultados e Conclusão

Week-neighborhood dengue incidence ranged from 0 to 379.5 cases/10,000 residents; large outbreaks occurred in 2016 and 2019. BACI-GLMM analyses revealed that, after accounting for weather effects and spatiotemporal dependencies, MDPPF was associated with a net 28.8% (95% CI 20.8–36.0) average reduction of dengue incidence in intervention neighborhoods, and a 21.4% (12.1–29.8) reduction in buffer neighborhoods. Average incidence, in contrast, was statistically comparable over trial areas before the intervention and over trial periods in control neighborhoods. These findings were robust to the removal of high-incidence outliers and to the separate analysis of epidemic-outbreak data.
Our pragmatic trial suggests that MDPPF can help prevent dengue – and, importantly, that it can do so (a) in the context of real-world, decentralized, large-scale vector-control operations and (b) in spite of several factors (e.g., mosquito immigration from untreated neighborhoods or notification records counting some non-local cases as local) likely attenuating intervention effects. MDPPF can thus be seen as a potentially useful addition to the dengue-control toolbox. In the common scenario of a 100,000-case outbreak, public-health managers could expect MDPPF to reduce the strain on the health-care system by ~29,000 (21,000–36,000) dengue cases.

Palavras-chave

Disease control, juvenile-hormone analogs