Spatial distribution of canine visceral leishmaniasis and its relationship with human visceral leishmaniasis in a municipality of Rio de Janeiro, Brazil

TL;DR

This study maps the spread of canine and human visceral leishmaniasis in Barra Mansa, Brazil, showing a strong link between urban and rural areas.

Contribution

The study provides new spatial insights into the relationship between canine and human visceral leishmaniasis in an urban-rural setting.

Findings

Most cases of canine and human visceral leishmaniasis were found in urban areas of Barra Mansa.

Persistent clusters of canine infections were near rural zones and preceded human cases by up to three years.

Over half of human cases were within 600 meters of canine infection clusters.

Abstract

Visceral leishmaniasis (VL) is an infectious disease that represents a considerable public health problem. In Brazil, VL was gradually expanded in all the territory and from rural to urban areas. A notable concentration of VL emerged in 2010 in the Médio Paraíba region of the state of Rio de Janeiro, where the municipality of Barra Mansa is located. However, information on the geographic distribution of VL in this municipality is scarce. Therefore, this study aimed to characterize the spatial distribution of VL in Barra Mansa from 2014 to 2023.

This exploratory epidemiological study involved creating point maps for human visceral leishmaniasis (HVL) and canine visceral leishmaniasis (CVL), as well as kernel density and cluster maps for CVL. In addition, maps were produced by superimposing the point maps of human cases with the cluster maps of canine infections.

In total, 99.1% of CVL-infected dogs and 100% of human cases were observed in the urban areas of the municipality. Persistent spatial clusters and hotspots were identified in urban areas adjacent to rural zones. Moreover, 55% of HVL cases were located within 600 m of a CVL spatial cluster. The closest clusters primarily formed up to 3 years before the HVL cases.

These results suggest a relationship between urban-rural interface characteristics and high density of CVL. They also highlight the spatial and temporal closeness between CVL and HVL, corroborating the influence of these factors on the maintenance of the disease cycle.

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