# Impact of Integrated Control Interventions on Sandfly Populations in Human and Canine Visceral Leishmaniasis Control in Araçatuba, State of São Paulo, Brazil

## TL;DR

This study evaluated how integrated control measures in Brazil affected sandfly populations, a key factor in spreading visceral leishmaniasis in humans and dogs.

## Contribution

The study provides insights into the effectiveness of integrated environmental and educational interventions in reducing sandfly populations in VL-endemic areas.

## Key findings

- Integrated interventions covered over 50% of properties and included environmental management and education.
- A 6% reduction in sandfly density was observed, though not statistically significant.
- Spatial analysis revealed uneven transmission risk across areas.

## Abstract

Visceral leishmaniasis (VL) is a serious disease that affects humans and dogs and can be fatal if left untreated. It is transmitted by sandflies that develop in the accumulation of decomposing organic matter. To reduce the reproduction of these insects, control measures such as yard cleaning and health education activities are routinely implemented. This study evaluated how integrated actions carried out by municipal surveillance teams—including environmental management, canine blood collection to assess disease circulation, and educational activities—influenced sandfly behavior in priority areas of Araçatuba, São Paulo. Between 2019 and 2021, light traps for insect attraction were installed in households to monitor the presence of sandflies, and spatial analyses were performed to identify areas of higher risk for canine transmission. Data obtained from the municipality’s historical series were also compared with those from the study. Interventions covered more than 50% of the visited properties, and environmental management guidance exceeded 85%. A total of 150 sandflies were collected, most of them belonging to the species Lutzomyia longipalpis, the main vector of VL. A 6% reduction in vector density was observed compared to previous years; however, this difference was not statistically significant. Spatial analysis indicated that the risk of transmission was not uniform across the geographic area. These results suggest that integrated environmental and educational actions may contribute to reducing sandfly populations. Likewise, identifying priority areas may strengthen surveillance and improve the effectiveness of VL control measures.

Visceral leishmaniasis (VL) is a serious vector-borne disease affecting humans and dogs, posing major public health challenges in endemic regions. Control efforts often target sandfly vectors, whose larvae and pupae develop in soil. Environmental management, such as removing organic matter, reducing moisture, and pruning vegetation, aims to limit breeding sites and reduce sandfly populations. This study evaluated the impact of integrated interventions on sandfly behavior in priority areas for VL control in Araçatuba, São Paulo, Brazil. The control strategy combined environmental management, canine surveys, and educational actions across seven local work areas (LWAs). Between 2019 and 2021, CDC-type light traps were installed in intra- and peridomiciliary settings at twelve properties in LWA 5. Spatial risk analysis for canine transmission was conducted in LWAs 3 and 5 using a Generalized Additive Model, with results presented as spatial odds ratios. Vector prevalence was analyzed using negative binomial regression compared to historical municipal data. Intervention coverage averaged 52.91% of visited properties (n = 15,905), ranging from 48% to 76.8% across LWAs. Adherence to environmental management exceeded 85%. Of the 150 sandflies collected, 98.67% were Lutzomyia longipalpis and 1.33% Nyssomyia neivai. A 6% reduction in vector density was observed compared with historical data, although this difference was not statistically significant. Spatial risk varied among LWAs, indicating heterogeneous transmission levels. These findings suggest that integrated environmental and educational interventions may contribute to reducing vector density and that identifying priority areas tends to support surveillance and the effectiveness of disease control actions.