title: Repeated stool sampling and use of multiple techniques enhance the sensitivity of helminth diagnosis: a cross-sectional survey in southern Lao People's Democratic Republic.
abstract: Intestinal parasitic infections are common in Lao People's Democratic Republic (Lao PDR). We investigated the accuracy of the Kato-Katz (KK) technique in relation to varying stool sampling efforts, and determined the effect of the concurrent use of a quantitative formalin-ethyl acetate concentration technique (FECT) for helminth diagnosis and appraisal of concomitant infections. The study was carried out between March and May 2006 in Champasack province, southern Lao PDR. Overall, 485 individuals aged ≥6 months who provided three stool samples were included in the final analysis. All stool samples were subjected to the KK technique. Additionally, one stool sample per individual was processed by FECT. Diagnosis was done under a light microscope by experienced laboratory technicians. Analysis of three stool samples with KK plus a single FECT was considered as diagnostic 'gold' standard and resulted in prevalence estimates of hookworm, Opisthorchis viverrini, Ascaris lumbricoides, Trichuris trichiura and Schistosoma mekongi infection of 77.9%, 65.0%, 33.4%, 26.2% and 24.3%, respectively. As expected, a single KK and a single FECT missed a considerable number of infections. While our diagnostic 'gold' standard produced similar results than those obtained by a mathematical model for most helminth infections, the 'true' prevalence predicted by the model for S. mekongi (28.1%) was somewhat higher than after multiple KK plus a single FECT (24.3%). In the current setting, triplicate KK plus a single FECT diagnosed helminth infections with high sensitivity. Hence, such a diagnostic approach might be utilised for generating high-quality baseline data, assessing anthelminthic drug efficacy and rigorous monitoring of community interventions.
authors.affiliation: National Institute of Public Health, Ministry of Health, Vientiane, Lao Democratic People's Republic; Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, P.O. Box, CH-4003 Basel, Switzerland.
authors.forename: Somphou
authors.initials: S
authors.lastname: Sayasone
authors.affiliation: Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, P.O. Box, CH-4003 Basel, Switzerland.
authors.forename: Jürg
authors.initials: J
authors.lastname: Utzinger
authors.affiliation: National Institute of Public Health, Ministry of Health, Vientiane, Lao Democratic People's Republic.
authors.forename: Kongsap
authors.initials: K
authors.lastname: Akkhavong
authors.affiliation: Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, P.O. Box, CH-4003 Basel, Switzerland. Electronic address: peter.odermatt@unibas.ch.
authors.forename: Peter
authors.initials: P
authors.lastname: Odermatt
mesh_terms: D000085:Acetates; D000293:Adolescent; D000328:Adult; D000723:Ancylostomatoidea / Q000302:isolation & purification; D000818:Animals; D001196:Ascariasis / Q000175:diagnosis; D017164:Ascaris lumbricoides / Q000302:isolation & purification; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005243:Feces / Q000469:parasitology*; D005260:Female; D005557:Formaldehyde; D006373:Helminthiasis / Q000175:diagnosis*; D006376:Helminths / Q000302:isolation & purification*; D006725:Hookworm Infections / Q000175:diagnosis; D006801:Humans; D007411:Intestinal Diseases, Parasitic / Q000175:diagnosis*; D007812:Laos; D008297:Male; D008853:Microscopy; D008875:Middle Aged; D009889:Opisthorchiasis / Q000175:diagnosis; D009891:Opisthorchis / Q000302:isolation & purification; D012552:Schistosomiasis / Q000175:diagnosis; D012680:Sensitivity and Specificity; D014257:Trichuriasis / Q000175:diagnosis; D014258:Trichuris / Q000302:isolation & purification; D055815:Young Adult
chemical_list: D000085:Acetates; D005557:Formaldehyde; C007650:ethyl acetate
keywords: Diagnosis; Helminthiasis; Lao People's Democratic Republic; Multiparasitism; Multiple diagnostic techniques; Multiple stool sampling