title: Comparison of individual and pooled stool samples for the assessment of soil-transmitted helminth infection intensity and drug efficacy.
abstract: BACKGROUND
  In veterinary parasitology samples are often pooled for a rapid assessment of infection intensity and drug efficacy. Currently, studies evaluating this strategy in large-scale drug administration programs to control human soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, and hookworm), are absent. Therefore, we developed and evaluated a pooling strategy to assess intensity of STH infections and drug efficacy.
  
  
  RESULTS
  Stool samples from 840 children attending 14 primary schools in Jimma, Ethiopia were pooled (pool sizes of 10, 20, and 60) to evaluate the infection intensity of STHs. In addition, the efficacy of a single dose of mebendazole (500 mg) in terms of fecal egg count reduction (FECR; synonym of egg reduction rate) was evaluated in 600 children from two of these schools. Individual and pooled samples were examined with the McMaster egg counting method. For each of the three STHs, we found a significant positive correlation between mean fecal egg counts (FECs) of individual stool samples and FEC of pooled stool samples, ranging from 0.62 to 0.98. Only for A. lumbricoides was any significant difference in mean FEC of the individual and pooled samples found. For this STH species, pools of 60 samples resulted in significantly higher FECs. FECR for the different number of samples pooled was comparable in all pool sizes, except for hookworm. For this parasite, pools of 10 and 60 samples provided significantly higher FECR results.
  
  
  CONCLUSIONS
  This study highlights that pooling stool samples holds promise as a strategy for rapidly assessing infection intensity and efficacy of administered drugs in programs to control human STHs. However, further research is required to determine when and how pooling of stool samples can be cost-effectively applied along a control program, and to verify whether this approach is also applicable to other NTDs.
authors.affiliation: Department of Medical Laboratory Sciences and Pathology, College of Public Health and Medical Sciences, Jimma University, Jimma, Ethiopia.
authors.forename: Zeleke
authors.initials: Z
authors.lastname: Mekonnen
authors.forename: Selima
authors.initials: S
authors.lastname: Meka
authors.forename: Mio
authors.initials: M
authors.lastname: Ayana
authors.forename: Johannes
authors.initials: J
authors.lastname: Bogers
authors.forename: Jozef
authors.initials: J
authors.lastname: Vercruysse
authors.forename: Bruno
authors.initials: B
authors.lastname: Levecke
mesh_terms: D000293:Adolescent; D000723:Ancylostomatoidea / Q000302:isolation & purification; D000818:Animals; D017164:Ascaris lumbricoides / Q000302:isolation & purification; D002648:Child; D002675:Child, Preschool; D019411:Clinical Laboratory Techniques / Q000379:methods*; D016903:Drug Monitoring / Q000379:methods*; D005002:Ethiopia; D005243:Feces / Q000469:parasitology*; D005260:Female; D006373:Helminthiasis / Q000175:diagnosis* / Q000469:parasitology*; D057166:High-Throughput Screening Assays / Q000379:methods*; D006801:Humans; D007410:Intestinal Diseases / Q000175:diagnosis* / Q000469:parasitology*; D007411:Intestinal Diseases, Parasitic; D008297:Male; D010274:Parasitology / Q000379:methods*; D014258:Trichuris / Q000302:isolation & purification