Co-endemicity of schistosomiasis and tegumentary leishmaniasis: Spatial co-clustering in endemic areas.

Objectives: Schistosomiasis and tegumentary leishmaniasis simultaneously affect areas in tropical and subtropical regions. Co-infected individuals show a less-than-optimal response to treatment and increased regulatory immune responses. However, no study has determined where Schistosoma-Leishmania co-infections are more likely to occur.

Methods: Data from The Global Health Observatory were collected to determine the worldwide endemicity status of schistosomiasis and tegumentary leishmaniasis in 2023. To determine co-endemic areas at a local level, an ecological study was conducted on confirmed cases of American tegumentary leishmaniasis and schistosomiasis in the State of Minas Gerais, Brazil, between 2013 and 2017. Local Indicators of Spatial Association analyses were used to search for co-endemic hotspots.

Results: Thirty-one countries were considered co-endemic, 23 of which presented active transmission of both diseases. Univariate Local Indicators of Spatial Association indicated 13 municipalities as high-high clusters for both American tegumentary leishmaniasis and schistosomiasis in Minas Gerais. Furthermore, bivariate Local Indicators of Spatial Association analyses identified 61 municipalities as high-high clusters, grouped in seven co-endemic hotspots.

Conclusion: Local Indicators of Spatial Association analyses are a useful tool for identifying areas where co-infection cases are more likely to occur. Similar analyses will assist authorities and healthcare providers when formulating policies and treating Schistosoma-Leishmania co-infected patients and will provide valuable data to enable researchers to explore the impact of this and other co-infections.