Performance of Urine Reagent Test Strips in Detecting Schistosoma haematobium Infection in Individual and Pooled Urine Samples

This study evaluated the performance of urine reagent strips (URSs) in detecting <i>Schistosoma haematobium</i> infection in individual and pooled urine samples. Between June 2022 and April 2023, 2634 urine samples (10 mL each) from school-age children (5-15 years) in 15 villages across Ethiopia's Afar, Benishangul-Gumuz, and Gambella regions were tested using urine filtration microscopy (UFM) and URSs for blood, a marker of <i>S. haematobium</i> eggs. Pooled samples from 5, 10, 20, and 40 individuals (one positive, others negative) were examined with both methods. UFM results were used to calculate URSs' sensitivity, specificity, and predictive values for detecting infection. A total of 2634 children were screened for <i>S. haematobium</i> infection. UFM detected <i>S. haematobium</i> eggs in 370 samples, while URSs identified infection in 414 children. URSs showed 64% sensitivity and 92% specificity for individual samples. The positive and negative predictive values for individual samples were 57% and 94%, respectively. Sensitivity for pooled samples ranged from 47% (pools of 40) to 53% (pools of 20). In pools with one positive sample, URSs misclassified 220 (50%), 109 (49.5%), 52 (47.0%), and 28 (50.9%) pools as negative for <i>S. haematobium</i> eggs for pool sizes 5, 10, 20, and 40, respectively. Sensitivity for individual samples was higher in children with heavy infection (92.5%) compared to light infection (55.9%), and sensitivity in pooled samples increased with infection intensity (<i>p</i> < 0.001). In conclusion, URSs may misclassify <i>S. haematobium</i> infection in children when samples are examined individually or in pools, potentially leading to unnecessary treatment or missed cases. However, URSs shows promise as a screening tool for detecting <i>S. haematobium</i> infection in areas with high infection intensity.