Comparison of Maxwell Kit-Based and NaOH-Based DNA Extraction Incorporated copro-DNA-SjTR1-qPCR Systems: Insights from Detecting Low-Intensity Schistosoma Japonicum Infections.

BACKGROUND AND

OBJECTIVE

Schistosomiasis remains a significant public health issue globally. This study aimed to compare the performance of two molecular diagnostic systems for the detection of low-intensity Schistosoma japonicum infections.

METHODS

A Maxwell kit-based copro-DNA-SjTR1-qPCR workflow (SjTR1-qPCR-S1) and a NaOH-based copro-DNA-SjTR1-qPCR workflow (SjTR1-qPCR-S2) were compared as integrated systems using faecal samples (n = 554) collected from an S. japonicum-endemic area in Leyte Province, the Philippines. The duplicated Kato-Katz (KK) was performed on three stool samples collected from different days for each participant. The diagnostic performance of KK and the SjTR1-qPCR systems were comprehensively compared with a composite reference where a participant was classified as positive if the KK was positive or any qPCR assay was positive.

RESULTS

The KK, SjTR1-qPCR-S1 and SjTR1-qPCR-S2 recorded positivity rates of 25.1% (139/554), 25.5% (141/554) and 29.8% (165/554), respectively. The overall S. japonicum positivity rate was 39.2% (217/554) as determined from the composite reference. Both SjTR1-qPCR systems exhibited excellent sensitivity in individuals with moderate-heavy (eggs per gram ≥ 100) and light (eggs per gram 10-99) infection intensity, with reduced sensitivity observed only in individuals with extremely low egg burden (eggs per gram 1-9). Globally, SjTR1-qPCR-S2 demonstrated significantly higher sensitivity (76.0%) compared with the KK (64.1%) and SjTR1-qPCR-S1 (65.0%) [p < 0.0161 and p = 0.0021, respectively, χ2m]. For samples positive in both SjTR1-qPCR systems (n = 125), SjTR1-qPCR-S1 showed a significantly higher median Ct value than SjTR1-qPCR-S2 (p < 0.0001, Wilcoxon signed-rank test). Both SjTR1-qPCR systems showed a significant negative correlation between Ct values and faecal egg counts (ρ = - 0.5947 for SjTR1-qPCR-S1, and ρ = - 0.4844 for SjTR1-qPCR-S2, both p < 0.0001). Moderate agreement was observed between both SjTR1-qPCR systems and the KK (κ = 0.560 and κ = 0.512, respectively). However, substantial agreement was found between SjTR1-qPCR-S1 and SjTR1-qPCR-S2 (κ = 0.748). The combined qPCR systems showed a sensitivity of 83.4%.

CONCLUSIONS

SjTR1-qPCR-S2 is cost effective and less reliant on specialised equipment compared with SjTR1-qPCR-S1. With further optimisation, the SjTR1-qPCR-S2 system can be a powerful and game-changing option for integration into the current surveillance network to support the eradication of schistosomiasis japonica.