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

Abstract

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.

Patients with severe schistosomiasis mansoni in Ituri Province, Democratic Republic of the Congo

“…However, in 2016 and 2017 we assessed S. mansoni infection and morbidity in 59 villages. We found high infection prevalence levels, particularly on the shores of Lake Albert and in the forest region [ 5 ]. In the latter area, schistosomiasis is largely unknown.…”

“…Indeed, during colonial times, its prevalence was low (around 20%) [ 11 ]. In 2017, record rates of more than 90% were observed, along with hepatosplenomegaly rates of up to 25% [ 5 ].…”

“…S. mansoni transmission around Lake Albert has been documented since colonial times [ 11 ]. A recent study showed intensive transmission of S. mansoni in the villages around the lake [ 5 ], as well as in Mandima and Pekele.…”

“…Between 2015 and 2017, three large cross-sectional studies were conducted in Ituri Province, in northeastern DRC. Both the prevalence of S. mansoni infection and its associated morbidity were found to being high in the province [ 5 , 6 ].…”