title: Evaluation of the performance of a rapid enzyme-linked immunosorbent assay in the detection of Anaplasma phagocytophilum antibodies in horses.
abstract: The aim of this study was to evaluate the performance of a commercially available rapid enzyme-linked immonosorbent assay, the Snap® 4Dx test, in the detection of Anaplasma phagocytophilum antibodies in horses. Two hundred apparently healthy horses (asymptomatic) and 244 animals showing clinical symptoms (symptomatic), were tested for A. phagocytophilum immunoglobulin G (IgG) antibodies using both the Snap® 4Dx kit and an indirect fluorescence antibody test (IFAT), with the latter serving as a comparative test. Horses belonging to the symptomatic group were also tested for evidence of active infection with A. phagocytophilum by analysis of IFAT IgM titers and PCR assay amplifying a specific fragment of the 16S rRNA gene. The overall agreement between the results obtained using the two tests, as well as the relative performance exhibited by the Snap® 4Dx test in the two groups, was assessed. Forty of the 45 animals (89%) testing positive for IgG antibodies using IFAT were correctly identified using Snap® 4Dx testing. The agreement between the results of the two tests was very high (k>0.9), with almost identical performances in both symptomatic and asymptomatic animals. Conversely, within the symptomatic group, only 44% (no. 11/25) of Snap® 4Dx positives appeared to be associated with a state of active infection, whereas the remaining 56% (no. 14/25) were related both to not infected animals (no. 1) and to horses whose status of infection needed further evaluations to be confirmed (no. 13/25). This study suggests that the Snap® 4Dx test could represent a valid screening method for use during epidemiological surveys of equine populations. Nevertheless, in-clinic application of the test does not appear to be merited.
authors.affiliation: 1 Department of Bio-Pathological Sciences and Hygiene of Animal and Food Production, Faculty of Veterinary Medicine, University of Perugia , Perugia, Italy .
authors.forename: Fabrizia
authors.initials: F
authors.lastname: Veronesi
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Passamonti
authors.forename: Annabella
authors.initials: A
authors.lastname: Moretti
authors.forename: Giulia
authors.initials: G
authors.lastname: Morganti
authors.forename: Doron Moshe
authors.initials: DM
authors.lastname: Vardi
authors.forename: Fulvio
authors.initials: F
authors.lastname: Laus
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Marenzoni
authors.forename: Andrea
authors.initials: A
authors.lastname: Spaterna
authors.forename: Mauro
authors.initials: M
authors.lastname: Coletti
authors.forename: Daniela Piergili
authors.initials: DP
authors.lastname: Fioretti
mesh_terms: D041081:Anaplasma phagocytophilum / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D016873:Ehrlichiosis / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D019084:Fluorescent Antibody Technique, Indirect / Q000662:veterinary; D006734:Horse Diseases / Q000175:diagnosis* / Q000382:microbiology; D006736:Horses; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D011933:Reagent Kits, Diagnostic / Q000662:veterinary*; D012680:Sensitivity and Specificity
chemical_list: D000907:Antibodies, Bacterial; D012336:RNA, Ribosomal, 16S; D011933:Reagent Kits, Diagnostic