Longevity of Schistosoma mansoni circulating cathodic antigens in filter paper dried urine spots

Objectives: This study aims to determine the temporal stability of Schistosoma mansoni circulating cathodic antigens (CCA) in filter paper-based dried urine spot (FP-DUS) samples under varying temperatures condition.

Methods: Urine from 20 children confirmed to have S. mansoni infection using Kato-Katz (at least 1 egg per gram of stool) and Schisto POC-CCA (2+ and 3+) methods were stored in form of FP-DUS and urine at room temperature (RT), 4 °C and -20 °C. Standard urine and FP-DUS Schisto POC-CCA methods were employed to detect CCA in urine and FP-DUS samples respectively, at weeks 4, 8 and 12. The results were reported as negative or positive (trace, 1+. 2+, and 3+).

Results: In FP-DUS samples, POC-CCA scores initially increase after 4-8 weeks, but then showed a decrease in intensity while still remaining positive, independent of temperature condition. From week 4 to week 12, at least 80 % of urine samples had POC-CCA score of 3+, independent of temperature condition. However, 2 urine samples at RT tested negative at weeks 8 and 12.

Conclusions: Despite the decrease in the intensity of test line in many samples, S. mansoni CCA remains stable and detectable in urine samples stored in FP-DUS.