Socioeconomic vulnerability associated with schistosomiasis in indigenous communities of southern Brazil

Schistosomiasis, a snail-borne Neglected Tropical Disease (NTD), has been caused by trematode blood flukes of genus Schistosoma . Besides the presence of gastropod snail intermediate hosts, disease spreading has been associated with poor sanitation and low human development index, particularly in communities living in deprived areas. Although present in 19/27 (70.4%) Brazilian States, schistosomiasis in vulnerable communities of non-endemic areas, particularly in southern and southeastern regions, remains to be fully established. Accordingly, the present study aimed to evaluate the seroprevalence of anti- S. mansoni antibodies based on ELISA-IgM and ELISA-IgG tests and associated risk factors to seropositivity in 713 individuals living in six indigenous communities of southern ( n = 412) and four in southeastern ( n = 301) Brazil. Overall seropositivity (IgM and/or IgG) was 5.3% (38/713; 95% CI: 3.9–7.2%). It was observed that there was a prevalence of 5.8% (24/412; 95% CI: 4.0-8.5%) in the southern and of 4.7% (14/301; 95% CI: 2.8–7.7%) in the southeastern region, but with no statistical difference. Surprisingly, seropositive individuals presented more IgM (33/38; 86.8%) than IgG (10/38; 26.3%) reaction, suggesting recent infection. Drinking river water and open-pit fecal disposal represented the univariate associations, whereas the final logistic regression retained community location/characteristic as the associated variable. These findings suggest that schistosomiasis surveillance should persevere in low-endemic areas, particularly in indigenous communities as environmental sentinels of pathogen distribution.