Seroprevalence and associated risk factors of strongyloidiasis in indigenous communities and healthcare professionals from Brazil

Abstract

Strongyloides stercoralis, a pathogenic roundworm, is considered endemic in several tropical and subtropical areas worldwide. Indigenous populations have the highest soil-transmitted helminthiases-related mortality rates, but the prevalence and risk factors associated with S. stercoralis in Brazilian indigenous populations have not been established. Thus, the present study aimed to assess the seroprevalence and associated risk factors for S. stercoralis in indigenous communities and the healthcare professionals serving them in Brazil. Indigenous populations living in nine communities and healthcare professionals were tested for anti- S. stercoralis antibodies by ELISA. A questionnaire was used to assess socio-epidemiological information. Associated risk factors for seropositivity were tested by chi-square or Fisher's exact tests, using univariate analyses and multivariate logistic regression. Overall, 174/463 (37.6%; CI 95%: 33.3-42.1) indigenous persons and 77/147 (52.4%; 95% CI: 44.3-60.3) healthcare professionals were seropositive for anti- S. stercoralis antibodies. Seropositivity among the two groups was statistically significant (p = 0.0016; OR = 0.547; 95% CI: 0.376-0.796) and revealed that healthcare professionals were 1.83 times more likely to be seropositive. The multivariate analysis showed that being male or being adult were also risk factors, while having a septic tank as a sanitary facility represented a protective factor for S. stercoralis exposure in indigenous persons. None of the variables evaluated were associated with S. stercoralis exposure in the professional group. The study herein has reported a high seroprevalence to Strongyloides stercoralis in indigenous communities of Brazil and healthcare professionals, warning for potential public health concerns of strongyloidiasis in such populations.

Fig 1. Sampling location and distribution of anti- S. stercoralis antibodies in indigenous communities of Paraná and São Paulo state, including indigenous populations and healthcare professionals.

(All components of the map are open source and open data—Direct link to source of Icons and symbols used: https://github.com/qgis/QGIS/tree/master/images/svg; Direct link of the boundaries from brazilian government official public data: https://geoftp.ibge.gov.br/cartas_e_mapas/bases_cartograficas_continuas/bc250/versao2021/post_gis/bc250_2021_11_18.zip; direct link to the base layer of the map: https://maps.wikimedia.org/#8/-24.009/-48.126).