title: Diagnostic performance of different fecal Lawsonia intracellularis-specific polymerase chain reaction assays as diagnostic tests for proliferative enteropathy in pigs: a review.
abstract: Traditionally, diagnosis of Lawsonia intracellularis-associated proliferative enteropathy (PE) has depended on necropsy and histology. Since the establishment of the etiologic role of L. intracellularis, a number of specific polymerase chain reaction (PCR) assays have been developed for the detection of DNA in feces. The present article is a systematic review of peer-reviewed publications on the application of L. intracellularis-specific fecal PCR as an antemortem diagnostic test for histologic lesions of PE in pigs. Based on this information, a range of diagnostic sensitivities (36-100%) and specificities (50-100%) of the published tests was calculated. Validity and confidence limits of the estimates varied considerably. The positive and negative predictive values of 6 different PCR assays were calculated for PE prevalence of 15%, 30%, 45%, 60%, 75%, and 90%, using a histologic case definition of PE and based on the reported test sensitivities and specificities. The simulated predictive values suggested that applying the fecal PCR assay as a diagnostic test is more likely to overestimate than underestimate the number of pigs having histologic lesions of PE under field conditions.
authors.affiliation: Department of Large Animal Sciences, University of Copenhagen, Groennegaardsvej 2, DK-1870 Frederiksberg C, Denmark. ken@life.ku.dk
authors.forename: Ken Steen
authors.initials: KS
authors.lastname: Pedersen
authors.forename: Patricia
authors.initials: P
authors.lastname: Holyoake
authors.forename: Helle
authors.initials: H
authors.lastname: Stege
authors.forename: Jens Peter
authors.initials: JP
authors.lastname: Nielsen
mesh_terms: D000818:Animals; D045824:Desulfovibrionaceae Infections / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D007410:Intestinal Diseases / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D020639:Lawsonia Bacteria; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary*; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis* / Q000382:microbiology