Comparison between Quantitative Polymerase Chain Reaction and Sodium Nitrate Flotation Microscopy in Diagnosing Soil-Transmitted Helminth Infections

ABSTRACT. There is evolving interest in alternate microscopy techniques and quantitative polymerase chain reaction (qPCR) to evaluate soil-transmitted helminth (STH) burden. Using data from a cross-sectional survey of 540 schoolchildren across six primary schools in three municipalities of Timor-Leste, we compared the performance of microscopy using sodium nitrate flotation (SNF) and qPCR in determining STH prevalence and infection intensity. Prevalence by qPCR was higher than SNF for Ascaris lumbricoides (17.5% versus 11.2%), hookworm (8.3% versus 1.2%), and Trichuris trichiura (4.7% versus 1.6%). Agreement between SNF and qPCR was fair for hookworm (κ = 0.21) and moderate for A. lumbricoides (κ = 0.59) and T. trichiura (κ = 0.44). Moderate or heavy intensity infections were identified in 15.9% of infections detected by SNF, whereas qPCR identified 36.1% as moderate or heavy infections using cycle threshold to eggs per gram conversion formulas. Quantitative PCR is a promising diagnostic technique, though further studies validating infection intensity correlates are required.