Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Monitoring drug efficacy against gastrointestinal nematodes when faecal egg counts are low: do the analytic sensitivity and the formula matter?


The faecal egg count reduction test (FECR) is the recommended technique to monitor anthelmintic drug efficacy in livestock. However, results are often inconclusive due to the low analytic sensitivity of the diagnostic technique or the conflict in results from FECR formulae. A novel experimental set-up was, therefore, used to compare the impact of analytic sensitivity and formulae on FECR results. Four McMaster techniques (analytic sensitivities 50, 33.3, 15 and 10) and a FLOTAC technique (analytic sensitivity ~ 1) were used on faecal samples of 30 calves with a FEC of less than 200 eggs per gram. True drug efficacies of 70%, 80% and 90% were experimentally mimicked by comparing FEC before and after dilution (3:10, 2:10 and 1:10, respectively). The FECR was summarized using group (FECR(1)) and individual (FECR(2)) based formulae. There was a significant increase in precision of FECR when the analytic sensitivity increased (p < 0.0001). The precision also depended on the formula used, FECR(1) (p < 0.05) resulting in more precise FECR compared to FECR(2). The accuracy of the FECR differed marginally between the two formulae (p = 0.06), FECR(1) being more accurate. In conclusion, the present study describes a novel methodology to compare techniques for the precision and the accuracy of their FECR results. The results underscored that techniques with high analytic sensitivity will improve the interpretation of FECR in animal populations where baseline FEC are low. They also point out that the precision of individual-based formulae is affected by the analytic sensitivity.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3


  1. Cabaret J, Berrag B (2004) Faecal egg count reduction test for assessing anthelmintic efficacy: average versus individually based estimations. Vet Parasitol 121:105–113

  2. Coles GC, Bauer C, Borgsteede FH, Geerts S, Klei TR, Taylor MA, Waller PJ (1992) World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) methods for the detection of anthelmintic resistance in nematodes of veterinary importance. Vet Parasitol 44:35–44

  3. Cringoli G, Rinaldi L, Maurelli MP, Utzinger J (2010) FLOTAC: new multivalent techniques for qualitative and quantitative copromicroscopic diagnosis of parasites in animals and humans. Nat Protoc 5:503–515

  4. Dobson RJ, Sangster NC, Besier RB, Woodgate RG (2009) Geometric means provide a biased efficacy result when conducting a faecal egg count reduction test (FECRT). Vet Parasitol 161:162–167

  5. El-Abdellati A, Charlier J, Geldhof P, Levecke B, Demeler J, von Samson-Himmelstjerna G, Claerebout E, Vercruysse J (2010) The use of a simplified faecal egg count reduction test for assessing anthelmintic efficacy on Belgian and German cattle farms. Vet Parasitol 169:352–357

  6. Levecke B, De Wilde N, Vandenhoute E, Vercruysse J (2009) Field validity and feasibility of four techniques for the detection of Trichuris in simians: a model for monitoring drug efficacy in public health? PLoS Negl Trop Dis 3(1):e366

  7. Ministry of Agriculture, Fisheries and Food (1986) Manual of veterinary parasitological laboratory techniques (reference book; 418), 3rd ed. Her Majesty’s Stationery Office (HMSO), London 160 pp

  8. Vercruysse J, Behnke JM, Albonico M, Ame SM, Angebault C, Bethony JM, Engels D, Guillard B, Hoa NTV, Kang G, Kattula D, Kotze AC, McCarthy JS, Mekonnen Z, Montresor A, Periago MV, Sumo L, Tchuem Tchuenté L.-A, Thach DTC, Zeynudin A, Levecke B (2011) A multinational trial of the efficacy of albendazole against soil-transmitted helminth infections in children. PloS Negl Trop Dis 5(3):e948

Download references


BL is funded by the Fund for Scientific Research–Flanders (Belgium) (F.W.O.–Vlaanderen). The research of J.C. is supported by the Agency of Innovation by Science and Technology (IWT Vlaanderen, projectOZM090697).

Author information

Correspondence to Bruno Levecke.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Levecke, B., Rinaldi, L., Charlier, J. et al. Monitoring drug efficacy against gastrointestinal nematodes when faecal egg counts are low: do the analytic sensitivity and the formula matter?. Parasitol Res 109, 953–957 (2011).

Download citation


  • Analytic Sensitivity
  • Drug Efficacy
  • Gastrointestinal Nematode
  • Absolute Bias
  • High Analytic Sensitivity