Schistosoma mansoni infection in residents of a riverside community in Eastern Amazon

Schistosoma mansoni worms cause a waterborne parasitic disease called schistosomiasis. It commonly affects individuals in lack of sanitation structure. In Brazil, Para state has Belem as one of the worst sanitation-ranking places in 2023, where schistosomiasis transmission was already documented. This study reports the occurrence of schistosomiasis in residents of Ilha das Oncas, an island next to Belem. Stool samples were obtained from participants over 2 years old, all residents from Furo do Rio Grande, one of the rivers on the island. The Kato-Katz technique was performed for parasite investigation in the stool samples. Each participant responded to a sociodemographic and clinical questionnaire. The residences were georeferenced for map designing. Three out of 263 participants were S. mansoni positive, all men, ages ranging from 19 to 41 years old, with low parasitic load. Malacological surveys were carried out, but no Biomphalaria snails were found. Risk factors for schistosomiasis establishment are present on the island, and the lack of sanitation enables it as a potential risk area. Malacological surveys are highly encouraged as preventive measures, as well as health surveillance for riverside populations, generating data that will help health authorities in the management and planning of preventive control actions. HIGHLIGHTS center dot The study revealed the presence of Schistosoma mansoni infection in residents of Ilha das Oncas. center dot The area had no previous reports of the disease. center dot Only male individuals tested positive for the infection. center dot No Biomphalaria snails were found in the peridomestic area of infected individuals. center dot Environmental conditions might enable schistosomiasis establishment on the island.