Epidemiology of Schistosoma mansoni infection in Ituri Province, north-eastern Democratic Republic of the Congo

Background: Schistosomiasis, caused by Schistosoma mansoni, is of great significance to public health in sub–Saharan Africa. In the Democratic Republic of Congo (DRC), information on the burden of S. mansoni infection is scarce, which hinders the implementation of adequate control measures. We assessed the geographical distribution of S. mansoni infection across Ituri province in north-eastern DRC and determined the prevailing risk factors. Methods/Principal findings: Two province–wide, community–based studies were conducted. In 2016, a geographical distribution study was carried out in 46 randomly selected villages across Ituri. In 2017, an in–depth study was conducted in 12 purposively–selected villages, across the province. Households were randomly selected, and members were enrolled. In 2016, one stool sample was collected per participant, while in 2017, several samples were collected per participant. S. mansoni eggs were detected using the Kato–Katz technique. In 2017, a point–of–care circulating cathodic S. mansoni antigen (POC–CCA) urine test was the second used diagnostic approach. Household and individual questionnaires were used to collect data on demographic, socioeconomic, environmental, behavioural and knowledge risk factors. Conclusions/Significance: Our results show that S. mansoni is highly endemic and a major health concern in Ituri province, DRC. Infection prevalence and intensity, and the prevailing socioeconomic, environmental, and behavioural risk factors in Ituri reflect intense exposure and alarming transmission rates. A robust plan of action is urgently needed in the province. Author summary: Intestinal schistosomiasis threatens many people in the tropical world, particularly those in Sub–Saharan Africa. Information on schistosomiasis in the Democratic Republic of Congo (DRC) is very scarce, which is a major barrier to planning and implementing efficient control programmes. We conducted two community–based studies with the objective of assessing the geographical distribution of S. mansoni infection across the Ituri province in north-eastern DRC and determining the prevailing risk factors. In 2016, a geographical distribution and in 2017, an in–depth studies were conducted in selected villages. Households were randomly selected and members, aged one year and older and present on the survey day, were enrolled. In 2016, one stool sample was examined per participant, whereas several stool samples were examined for each participant in 2017. S. mansoni eggs were detected using the Kato–Katz technique. A point–of–care circulating cathodic S. mansoni antigen (POC–CCA) urine test was also used in 2017. Household and individual questionnaires were used to collect demographic, socioeconomic, environmental, behavioural and knowledge data. In 2016, of the 2,131 participants, 40.0% of were infected with S. mansoni. Of the 707 participants in 2017, 73.1% were tested positive for S. mansoni. Infection prevalence increased from north to south and from west to east. Exposure to the Lake Albert and villages’ altitude were main drivers of the distribution. Men and women had the same infection risk. Infection prevalence and intensity peaked in the age groups between 10 and 29 years. Preschool children were highly infected. Poor housing structure, proximity to water bodies, long–term residence in a community, lack of latrine in the household, and swimming and washing in local water bodies were the main risk factors. Our results confirm that S. mansoni is highly endemic in Ituri province, DRC. Both infection prevalence and intensity indicate intense exposure and alarming transmission. Control interventions are warranted and should pay attention to high–risk communities and population groups, including preschool children.