Harnessing Molecular Techniques to Inform Species-Specific Hookworm Prevalence and Infection Intensity and Detect Strongyloides in Dak Lak Province, Vietnam

Quantitative polymerase chain reaction (qPCR) is an increasingly recognized diagnostic tool for soil-transmitted helminths (STHs), overcoming limitations of microscopy. We compared qPCR with Kato-Katz (KK) and sodium nitrate flotation (SNF; specific gravities 1.2 and 1.3) in determining STH prevalence and infection intensity using samples from a community survey of 351 people in Dak Lak province, Vietnam. Established correlation formulas were used to convert qPCR cycle threshold values to eggs per gram to compare infection intensity. Sensitivity, specificity, and agreement between methods were also investigated. Hookworm was the predominant STH detected, with prevalences of 70.3% (95% CI: 63.6-76.9) by qPCR, 59.1% (95% CI: 46.3-72.4) by 1.2SNF, 56.5% (95% CI: 43.2-69.4) by 1.3SNF, and 47.8% (95% CI: 34.6-57.6) by KK. Detection of Ascaris lumbricoides and Trichuris trichiura was low across methods. Prevalences of zoonotic hookworm Ancylostoma ceylanicum and Strongyloides species by qPCR were 3.0% (95% CI: 1.3-6.4) and 17.3% (95% CI: 8.1-22.3), respectively. qPCR detected higher prevalence of moderate- (8.3% versus <2%) and heavy-intensity (9.4% versus 0%) infections than microscopy. The sensitivities of microscopy methods were 81.0% (1.2SNF), 75.8% (1.3SNF), and 67.4% (KK). Diagnostic agreement for hookworm was moderate between qPCR and KK and between qPCR and 1.3SNF, and it was good between qPCR and 1.2SNF. The superior performance of qPCR in detecting hookworm coupled with the capacity to differentiate hookworm species and detect Strongyloides spp. supports the role of qPCR to inform control strategies, particularly for zoonotic reservoirs and use of macrocyclic lactones.