# Distribution of Biomphalaria sp. and other limnic mollusks in the state of Ceará: a potential effect of the São Francisco River Transposition Project

## TL;DR

This study examines how a river transposition project in Ceará may spread snails that carry schistosomiasis, increasing disease risk in new areas.

## Contribution

The study identifies the distribution of Biomphalaria snails and assesses schistosomiasis transmission risk in areas affected by a large-scale water project.

## Key findings

- Biomphalaria straminea was found in 85.7% of surveyed water bodies across three municipalities.
- Eight water bodies were classified as having high epidemiological risk for schistosomiasis transmission.
- No Schistosoma mansoni larvae were detected, but nonpathogenic trematode larvae were observed.

## Abstract

The São Francisco River Integration Project (PISF) may facilitate the spread of intermediate hosts of schistosomiasis to previously unaffected areas, potentially increasing disease transmission owing to human migration and environmental changes. This study aimed to describe the distribution of freshwater mollusk fauna along the river basins involved in the PISF in the state of Ceará.

A descriptive cross-sectional study was conducted in three municipalities in the state of Ceará (Brejo Santo, Jati, and Mauriti) located along the Meta 2N axis of the PISF. Mollusks were collected from 21 water bodies near the resettlement areas (productive rural villages). Morphological identification of freshwater snails and screening for Schistosoma mansoni (S. mansoni) cercariae were also performed. Environmental variables were recorded, and the potential for transmission was assessed according to the Brazilian Ministry of Health guidelines.

Overall, 765 Biomphalaria specimens were collected, with Biomphalaria straminea being the only species identified. This genus occurred in all three municipalities and 85.7% of the surveyed water bodies. The other identified mollusk genera included Melanoides, Drepanotrema, Physa, Pomacea, and members of the class Bivalvia. No S. mansoni larvae were found, and only nonpathogenic trematode larvae were observed. Eight water bodies were classified as having a high epidemiological risk.

The surveyed communities represent areas with the potential to sustain schistosomiasis transmission. These findings highlight the importance of developing intersectoral strategies to address the issue from a One Health perspective and to implement effective interventions in the areas impacted by the project.