Liver and bladder morbidity in a Schistosoma mansoni and haematobium co-endemic area in the Democratic Republic of Congo

BACKGROUND: Both Schistosoma (S.) mansoni and S. haematobium are co-endemic in many regions of the Democratic Republic of the Congo (DRC). However, little is known about the clinical implications of mixed Schistosoma infections for the affected communities. This study determined Schistosoma-related morbidity patterns in single and mixed Schistosoma infections in DRC. METHODS: Between November 2015 and March 2016, we conducted a community-wide study in the rural community of Kifwa II village, west of the DRC. According to WHO guidelines, Schistosoma-specific morbidity was assessed using ultrasound. Data were summarized using descriptive statistics, the Chi-square test, and logistic regression. PRINCIPAL FINDINGS: Ultrasound examinations were performed on 825 individuals aged 1-80 years. The results indicated that 68% (559) of the participants had bladder morbidity, with a higher prevalence observed in those with mixed infections compared to those with single S. haematobium infection (p = 0.001). The prevalence of liver morbidity was 64.6% (533), showing no difference between those with mixed and single S. mansoni infections (p = 0.174). Bladder morbidity was significantly associated with age, reflected by increasing odds ratios for different age groups: 1.6 (p = 0.035) for those aged 11-20 years, 1.7 (p = 0.046) for those aged 21-30 years, 2.2 (p = 0.005) for those aged 41-50 years, 3.2 (p = 0.001) for those aged 51-60 years, and 3.6 (p = 0.006) for those aged over 60 years. Similarly, liver morbidity was significantly associated with age, showing increasing odds ratios for different age groups: 1.7 (p = 0.026) for 21-30 years, 3.2 (p < 0.001) for 41-50 years, 4.5 (p < 0.001) for 51-60 years, and 3.1 (p = 0.011) for those over 60 years. However, mixed infection was associated with a significantly increased risk of bladder morbidity (aOR=2.3; p < 0.001), but not liver morbidity (aOR=1.4; p = 0.125). CONCLUSION: Schistosoma-related morbidity is common in the study area, impacting individuals of all ages and calling for regular mass drug administration, considering the adult population, improved WASH infrastructure, and health education to encourage behavioural change. Additionally, mixed infections have a positive effect on bladder morbidity, with possible implications for disease control.