Fig 3. Relationship between Cq values measured by qPCR and eggs per gram estimated using Double-Slide Kato-Katz.

Soil-transmitted helminth ova or DNA were detected by Kato-Katz and qPCR in stool samples collected from children aged 2–12 years in rural Bangladesh (N = 2,799). The black solid line is the LOESS smoother for values that were classified as positive using both tests. Gray points indicate results that were negative by qPCR but positive by Kato-Katz; they are gray because Kato-Katz cannot differentiate between hookworm species. The Kendall’s tau comparing eggs per gram and Cq values was -0.442 for A. lumbricoides, -0.346 for N. americanus, -0.266 for A. ceylanicum, and -0.248 for T. trichiura (for each, the p-value was < 0.001).