Ultrasound evaluation of urinary tract morbidity in adults living in a Schistosoma haematobium endemic region in Mozambique

Ultrasound-based assessment of urinary tract morbidity remains central to the evaluation of Schistosoma haematobium infection, but the WHO Niamey protocol is operationally complex and has been used mainly in children and higher-transmission settings. We aimed to describe urinary tract structural abnormalities in adults living in an endemic area of Mozambique using a preliminary application of a modified Niamey-derived protocol adapted for point-of-care ultrasound (POCUS) and to compare these findings with parasitological and molecular evidence of infection.

We conducted a descriptive cross-sectional study between April and October 2018 among individuals aged 15 years or older living in the Chókwè Health and Demographic Surveillance System area, Mozambique. Schistosoma haematobium infection was defined by urine filtration and/or DNA detection. Urinary tract ultrasound was performed using a simplified Niamey-derived POCUS protocol. All examinations were performed by a trained investigator, and a subset of images was reviewed remotely for interobserver agreement.

Our study included 912 ultrasound exams. The prevalence of ultrasound detected urinary tract abnormalities was 37.9% (95% CI 34.8%-41.2%). Of these, 14.5% were positive for Schistosoma haematobium. We found that 11.8% (95% CI 9.7%-13.9%) had a lower urinary tract abnormality and 29.3% (95% CI 26.7%-32.7%) had an upper urinary tract abnormality. The renal pelvis was the most common location for ultrasound abnormalities (23.1%), followed by the ureters (20.4%) and the bladder wall (11.6%). Interobserver agreement was substantial for bladder findings (κ = 0.65), ureteral findings (κ = 0.78), and the final ultrasound score (κ = 0.63) and moderate for kidney findings (κ = 0.59).

In this adult population from a historically endemic area, POCUS identified a substantial burden of urinary tract structural abnormalities despite a relatively low prevalence of current infection. In adults, particularly in low-prevalence or post-control settings, such abnormalities should not be interpreted as specific markers of active schistosomiasis, because they may reflect chronic sequelae, prior infection, or other urinary tract pathology. The study supports the feasibility of a simplified POCUS-adapted protocol under controlled research conditions with a trained operator; future implementation studies are needed before broader use by general clinicians can be recommended.

Not applicable.