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

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.

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+).

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.

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.