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. First, in 2016, a geographical distribution study was carried out in 46 randomly selected villages, covering 12 of the 36 health districts across Ituri. Second, in 2017, an in-depth study was conducted in 12 purposively-selected villages, across six health districts. In each study village, 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 collected per participant, while in 2017, several samples were collected per participant. S. mansoni eggs were detected using the Kato-Katz technique. The 2017 study also incorporated a point-of-care circulating cathodic S. mansoni antigen (POC-CCA) urine test. Household and individual questionnaires were used to collect data on demographic, socioeconomic, environmental, behavioural and knowledge risk factors.
The 2016 study included 2,131 participants, 40.0% of whom had S. mansoni infections. Infection prevalence in the villages ranged from 0 to 90.2%. The 2017 study included 707 participants, of whom 73.1% tested positive for S. mansoni. Infection prevalence ranged from 52.8 to 95.0 % across the health districts visited. In general, infection prevalence increased from north to south and from west to east. Exposure to the waters of Lake Albert and the village altitude above sea level were associated with the distribution.
Both men and women had the same infection risk (odds ratio [OR] 1.2, 95% confidence interval [CI] 0.82-1.76). Infection prevalence and intensity peaked in the age groups between 10 and 29 years. Preschool children were highly infected (62.3%). Key risk factors were poor housing structure (OR 2.1, 95% CI 1.02-4.35), close proximity to water bodies (OR 1.72, 95% CI 1.1-2.49), long-term residence in a community (OR 1.41, 95% CI 1.11-1.79), lack of latrine in the household (OR 2.00, 95% CI 1.11-3.60), and swimming (OR 2.53, 95% CI 1.20-5.32) and washing (OR 1.75, 95% CI 1.10-2.78) in local water bodies. A family history of schistosomiasis (OR 0.52, 95%, 95% CI 0.29-0.94) and knowledge of praziquantel treatment (OR 0.33, 95% CI 0.16-0.69) were protective risk factors, while prevention knowledge (OR 2.35, 95% CI 1.36-4.08) was associated with increased infection risk.
Conclusions/Significance: Our results confirm high endemicity of S. mansoni in Ituri province, DRC. Both the prevalence and intensity of infection, and its relationship with the prevailing socioeconomic, environmental, and behavioural risk factors indicate intense exposure and alarming transmission levels. The study findings warrant control interventions that pay particular attention to high-risk communities and population groups, including preschool children.
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