title: Multi-parallel qPCR provides increased sensitivity and diagnostic breadth for gastrointestinal parasites of humans: field-based inferences on the impact of mass deworming.
abstract: BACKGROUND
  Although chronic morbidity in humans from soil transmitted helminth (STH) infections can be reduced by anthelmintic treatment, inconsistent diagnostic tools make it difficult to reliably measure the impact of deworming programs and often miss light helminth infections.
  
  
  METHODS
  Cryopreserved stool samples from 796 people (aged 2-81 years) in four villages in Bungoma County, western Kenya, were assessed using multi-parallel qPCR for 8 parasites and compared to point-of-contact assessments of the same stools by the 2-stool 2-slide Kato-Katz (KK) method. All subjects were treated with albendazole and all Ascaris lumbricoides expelled post-treatment were collected. Three months later, samples from 633 of these people were re-assessed by both qPCR and KK, re-treated with albendazole and the expelled worms collected.
  
  
  RESULTS
  Baseline prevalence by qPCR (n = 796) was 17 % for A. lumbricoides, 18 % for Necator americanus, 41 % for Giardia lamblia and 15% for Entamoeba histolytica. The prevalence was <1% for Trichuris trichiura, Ancylostoma duodenale, Strongyloides stercoralis and Cryptosporidium parvum. The sensitivity of qPCR was 98% for A. lumbricoides and N. americanus, whereas KK sensitivity was 70% and 32%, respectively. Furthermore, qPCR detected infections with T. trichiura and S. stercoralis that were missed by KK, and infections with G. lamblia and E. histolytica that cannot be detected by KK. Infection intensities measured by qPCR and by KK were correlated for A. lumbricoides (r = 0.83, p < 0.0001) and N. americanus (r = 0.55, p < 0.0001). The number of A. lumbricoides worms expelled was correlated (p < 0.0001) with both the KK (r = 0.63) and qPCR intensity measurements (r = 0.60).
  
  
  CONCLUSIONS
  KK may be an inadequate tool for stool-based surveillance in areas where hookworm or Strongyloides are common or where intensity of helminth infection is low after repeated rounds of chemotherapy. Because deworming programs need to distinguish between populations where parasitic infection is controlled and those where further treatment is required, multi-parallel qPCR (or similar high throughput molecular diagnostics) may provide new and important diagnostic information.
authors.affiliation: Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, MD, USA. alice.easton@nih.gov.|Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK. alice.easton@nih.gov.
authors.forename: Alice V
authors.initials: AV
authors.lastname: Easton
authors.affiliation: Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK. r.oliveira11@imperial.ac.uk.
authors.forename: Rita G
authors.initials: RG
authors.lastname: Oliveira
authors.affiliation: Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, MD, USA. elise.o'connell@nih.gov.
authors.forename: Elise M
authors.initials: EM
authors.lastname: O'Connell
authors.affiliation: School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda. stellakepha2005@yahoo.com.
authors.forename: Stella
authors.initials: S
authors.lastname: Kepha
authors.affiliation: Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya. CMwandawiro@kemri.org.
authors.forename: Charles S
authors.initials: CS
authors.lastname: Mwandawiro
authors.affiliation: Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya. SNjenga@kemri.org.
authors.forename: Sammy M
authors.initials: SM
authors.lastname: Njenga
authors.affiliation: Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya. jimmykihara09@gmail.com.
authors.forename: Jimmy H
authors.initials: JH
authors.lastname: Kihara
authors.affiliation: Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya. cmwatele@gmail.com.
authors.forename: Cassian
authors.initials: C
authors.lastname: Mwatele
authors.affiliation: Neglected Tropical Diseases Research Unit, Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya. MOdiere@kemricdc.org.
authors.forename: Maurice R
authors.initials: MR
authors.lastname: Odiere
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK. simon.brooker@gatesfoundation.org.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Brooker
authors.affiliation: Royal Veterinary College, University of London, Hertfordshire, UK. jowebster@rvc.ac.uk.
authors.forename: Joanne P
authors.initials: JP
authors.lastname: Webster
authors.affiliation: Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK. roy.anderson@imperial.ac.uk.
authors.forename: Roy M
authors.initials: RM
authors.lastname: Anderson
authors.affiliation: Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, MD, USA. tnutman@niaid.nih.gov.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Nutman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015766:Albendazole / Q000627:therapeutic use*; D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D000981:Antiprotozoal Agents / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D016785:Cryptosporidium parvum / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D004748:Entamoeba histolytica / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D005243:Feces / Q000469:parasitology; D005260:Female; D016829:Giardia lamblia / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D007411:Intestinal Diseases, Parasitic / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology / Q000469:parasitology; D007630:Kenya / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009348:Nematoda / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D010271:Parasites / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012987:Soil / Q000469:parasitology; D055815:Young Adult
chemical_list: D000871:Anthelmintics; D000981:Antiprotozoal Agents; D012987:Soil; D015766:Albendazole
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