Introduction:_x000D_
Bilharziasis, or schistosomiasis, is caused by infection with blood flukes belonging to the genus Schistosoma. The three primary species infecting humans are Schistosoma haematobium, S. japonicum, and S. mansoni. These parasites have a complex life cycle involving two hosts: freshwater snails as intermediate hosts and humans as definitive hosts. Clinically, schistosomiasis may present as acute or chronic disease affecting either the genitourinary or hepato-intestinal systems. Although endemic in 78 nations, the vast majority of schistosomiasis cases occur in sub-Saharan Africa._x000D_
Methodology:_x000D_
A multidisciplinary protocol was implemented to screen for schistosomiasis, ensuring informed consent and participant rights. Data were collected using a structured questionnaire in face-to-face interviews to assess epidemiological risks, clinical presentations, and complications. Additionally, electronic medical records were reviewed._x000D_
Microbiological tests included urine microscopic examination for S.haematobium eggs and hematuria, along with serological antibody detection, namely ELISA and ICT pink(P). In a participant subgroup, a point-of-care ICT(B)(B) test was performed on finger-prick blood along with ICT Black(B)(S) on serum samples. The study also assessed prevalence of other neglected tropical diseases among participants._x000D_
Biochemical and hematological analyses, including complete blood counts and liver and kidney function tests, were performed for all participants. Abdominal ultrasound assessed genitourinary and liver abnormalities and evaluated its association with schistosomiasis-positive cases. A 12-month follow-up evaluated responses after praziquantel treatment. Clinical improvement meant resolution of symptoms, while parasitological cure was defined by absence of eggs and/or hematuria. Serological recovery was indicated by conversion to negative results in ELISA, ICT, or both. A reduction in antibody titers between pre- and post-treatment phases further supported treatment efficacy and test specificity. Improvement toward normal ranges in biochemical parameters was also considered indicative of recovery._x000D_
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Results: _x000D_
A total of 522 participants from sub-Saharan West Africa (25.7% female, mean age 42.7) were studied. Recent travel to home countries or water contact was more common among Schistosoma-positive males, with a trend toward higher prevalence among males from Senegal and Mali. Six participants had egg-positive urine. Prevalence was 27.7% by ICT(P) and 22.9% by ELISA, showing fair agreement (κ=0.340). _x000D_
Among a subset of participants, the ICT(B) assays, as long as the ICT(P), and ELISA provided complementary information on schistosomiasis prevalence and antibody response, facilitating the evaluation of diagnostic performance across different specimen types. Prevalence estimates varied by test: 15.8% by ELISA, 24.3% by ICT pink, 46.5% by ICT(B)(S), and 28.7% by ICT(B)(B), reflecting differences in sensitivity and sample source._x000D_
Other neglected tropical diseases included HIV (1.73%), HCV (1.93%), Strongyloides (7.7%), and HBV surface antigen (12.9%). Anemia and hematuria were more frequent among women, whereas abnormal GFR and elevated creatinine were more common in schistosoma-positive men. ALT and GGT levels were also elevated in schistosoma-positive individuals._x000D_
Ultrasound findings were ONLY significantly associated with those with concurrent active HBV infection. Praziquantel treatment significantly reduced clinical symptoms. At follow-up, 54.1% of ELISA-positive and 24.7% of ICT-positive individuals had converted to negative. _x000D_
Conclusions:_x000D_
A seroprevalence of 35.8% indicates a high disease burden, with men more affected due to water-contact occupations like fishing and agriculture. Symptom reporting varied between questionnaires and clinical records, suggesting under-detection likely caused by symptom normalization or stigma. The serum (ICT)(P) and ICT(B) showed the highest positivity and sensitivity compared to ELISA and other tests, effectively detecting both IgG and IgM antibodies in chronic infections. Other NTDs PVC was ranging from 1.7% HIV, 1.93% HCV, 7.7% strongyloidiasis to 12.9% HBV. Co-infection PVC was 66.7%,10%, 35.9% and 35.8%, respectively.Treatment with an enhanced praziquantel regimen (two doses of 60 mg/kg) led to over 70% symptom resolution and significant drop in antibody levels in most ELISA-positive patients. ICT(B)(S), detected more positivity rates than the other tests
| Date of Award | 17 Dec 2025 |
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| Original language | English |
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| Awarding Institution | - Universitat Autònoma de Barcelona (UAB)
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| Supervisor | Silvia Roura Diez (Director), Pere Joan Cardona Iglesias (Director) & Gema Fernandez Rivas (Director) |
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