Prospective cohort study using ultrasonography of Schistosoma haematobium-infected migrants.

Background Chronic infection with Schistosoma haematobium may lead to serious complications, including bladder carcinoma. Although it is recommended that only bladder masses not regressing within 6 months after praziquantel intake should be investigated invasively, cystoendoscopy is still often performed at diagnosis even in the absence of further signs of concern. No prospective study so far evaluated the evolution of bladder lesions after treatment in case of no risk of reinfection, which could inform case management. Methods Adult African migrants with active S. haematobium infection, as assessed by positive urine PCR or microscopy for eggs in urine or bladder biopsy, underwent urinary tract ultrasound at enrolment and at 1, 3, 6, 12, and 24 months after praziquantel treatment. Patients in advanced pregnancy or with known Schistosoma-unrelated chronic pathology of the urinary tract were excluded. Results Twenty-one patients, aged 18-29 years, participated in the study; 10 (47.6%) had bladder masses on ultrasound. Follow-up ≥6 months was completed by 16 (76.2%) patients; ≥12 months by 14 (66.7%), and 24 months by 11 (52.4%). All patients with bladder lesions on enrolment completed a follow-up of ≥6 months. Lesions resolved completely by 6 months in all cases and no new development/re-appearance was observed. Conclusions This is the first prospective, long-term follow-up study with ultrasound of patients with urinary schistosomiasis outside endemic areas. Mucosal masses in young patients regressed after treatment without recurrence, supporting the recommendation that invasive procedures should be avoided unless lesions or other symptoms/signs of concern persist for > 6 months. Further studies should assess the evolution of bladder lesions after treatment in larger populations, including older age groups, and, ideally, with parallel assessment of other biomarkers of urinary pathology and of residual S. haematobium active infection.