Background: Intestinal schistosomiasis is highly endemic in Tanzania and mass drug administration (MDA) using praziquantel is the mainstay of control. MDA covers only school aged children and does not include other public health measures. The Ijinga schistosomiasis project examines the impact of an intensified MDA protocol combined with additional public health interventions. It aims to investigate the feasibility of eliminating intestinal schistosomiasis in a highly endemic African setting using an integrated community-based approach. We report baseline data on S.mansoni prevalence, intensity of infection, related hepatosplenic morbidities and their associated factors.
Methods: A cross sectional study was conducted among 930 individuals aged 1-95 years on Ijinga Island, north-western Tanzania in September 2016. Single stool and urine samples were collected and processed using Kato Katz (KK) technique and point-of-care Circulating Cathodic (POC-CCA) antigen test for detection of S.mansoni eggs and antigen respectively. All participants received ultrasonography for S.mansoni hepatosplenic morbidities. For statistical analyses Fisher’s exact test, chi-square test, student-t-test, ANOVA and linear regression were used where applicable.
Results: Based on KK technique and POC-CCA test, 68.9% and 94.5% respectively were infected with S.mansoni . The overall geometrical mean eggs per gram (GMepg) of faeces was 85.7epg. A total of 27.1%, 31.2% and 51.9% of the participants had periportal fibrosis (PPF-grade C-F), splenomegaly and hepatomegaly. Risk factors for PPF were being male (aRR=1.08, P <0.01), belong to the age group 16-25 years (aRR=1.23, P <0.01), 26-35 years (aRR=1.42, P <0.001), 36-45 years (aRR=1.56, P <0.001) and ≥ 46 years (aRR=1.64, P <0.001). The length of the left liver lobe was associated with being female ( P <0.03), the age group 1-5 years ( P <0.013), 6-15 years ( P <0.04) and S.mansoni intensity of infection ( P <0.034). Male sex (aRR=1.15, P <0.001) and the age groups 16-25 years (aRR=1.27, P <0.02) or 26-35 years (aRR=1.32, P <0.01) were associated with splenomegaly.
Conclusion : Schistosoma mansoni infection and related morbidities are common in the study area. Age, sex and intensity of infection were associated with periportal fibrosis. With a prevalence of >50% in each age group we recommend MDA to the entire community.