title: Detection of Strongylus vulgaris in equine faecal samples by real-time PCR and larval culture - method comparison and occurrence assessment.
abstract: BACKGROUND
  Strongylus vulgaris has become a rare parasite in Germany during the past 50 years due to the practice of frequent prophylactic anthelmintic therapy. To date, the emerging development of resistance in Cyathostominae and Parascaris spp. to numerous equine anthelmintics has changed deworming management and the frequency of anthelmintic usage. In this regard, reliable detection of parasitic infections, especially of the highly pathogenic S. vulgaris is essential. In the current study, two diagnostic methods for the detection of infections with S. vulgaris were compared and information on the occurrence of this parasite in German horses was gained. For this purpose, faecal samples of 501 horses were screened for S. vulgaris with real-time PCR and an additional larval culture was performed in samples of 278 horses. A subset of 26 horses underwent multiple follow-up examinations with both methods in order to evaluate both the persistence of S. vulgaris infections and the reproducibility of each diagnostic method.
  
  
  RESULTS
  The real-time PCR revealed S. vulgaris-DNA in ten of 501 investigated equine samples (1.9%). The larval culture demonstrated larvae of S. vulgaris in three of the 278 samples (1.1%). A direct comparison of the two methods was possible in 321 samples including 43 follow-up examinations with the result of 11 S. vulgaris-positive samples by real-time PCR and 4 S. vulgaris-positive samples by larval culture. The McNemar's test (p-value = 0.016) revealed a significant difference and the kappa values (0.525) showed a moderate agreement between real-time PCR and larval culture.
  
  
  CONCLUSIONS
  The real-time PCR detected a significantly higher proportion of positives of S. vulgaris compared to larval culture and should thus be considered as a routine diagnostic method for the detection of S. vulgaris in equine samples.
authors.affiliation: Comparative Tropical Medicine and Parasitology, Veterinary Faculty, Ludwig-Maximilians-University, Munich, Germany. alexandra.kaspar@tropa.vetmed.uni-muenchen.de.
authors.forename: A
authors.identifier: http://orcid.org/0000-0002-7367-5311
authors.initials: A
authors.lastname: Kaspar
authors.affiliation: Comparative Tropical Medicine and Parasitology, Veterinary Faculty, Ludwig-Maximilians-University, Munich, Germany.|Present address: Parasite Consulting GmbH, Wendschatzstrasse 8, CH-3006, Berne, Switzerland.
authors.forename: K
authors.initials: K
authors.lastname: Pfister
authors.affiliation: Department of Veterinary Science, M.H. Gluck Equine Research Center, University of Kentucky, Lexington, KY, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Nielsen
authors.affiliation: Comparative Tropical Medicine and Parasitology, Veterinary Faculty, Ludwig-Maximilians-University, Munich, Germany.|Present address: National Centre of Vector Entomology, Institute for Parasitology, Vetsuisse Faculty, University of Zurich, CH-8006, Zurich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Silaghi
authors.affiliation: Department of Statistics, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Fink
authors.affiliation: Comparative Tropical Medicine and Parasitology, Veterinary Faculty, Ludwig-Maximilians-University, Munich, Germany.|Present address: ParaDocs Laboratory, Ismaning, Germany.
authors.forename: M C
authors.initials: MC
authors.lastname: Scheuerle
mesh_terms: D000818:Animals; D005243:Feces / Q000469:parasitology*; D006736:Horses; D007814:Larva / Q000502:physiology; D010270:Parasite Egg Count / Q000662:veterinary; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary*; D013319:Strongyle Infections, Equine / Q000175:diagnosis / Q000469:parasitology*; D013323:Strongylus / Q000302:isolation & purification*
keywords: Equine; Germany; Larval culture; Real-time PCR; Strongyle; Strongylus vulgaris