title: Performance of a commercial serum ELISA for the detection of antibodies to Neospora caninum in whole and skim milk samples.
abstract: Control of Neospora caninum infection in cattle depends on specific, ante-mortem detection of infected animals and limiting their use as breeding stock or by culling. The objective of the present study was to determine appropriate cut-off values and diagnostic performance of a milk ELISA test using whole and skim milk in a commercial serum ELISA test (IDEXX Neospora Ab). Serum and milk samples were obtained from a total of 475 lactating cows from two herds with and two herds without a previous history of N. caninum-associated abortion. Overall seroprevalence determined by the ELISA was 18.3%. Compared to serum ELISA values, correlation and overall performance assessed by receiver operating characteristic analysis was higher when either whole or skim milk samples were diluted 1:2 compared to undiluted or 1:5 diluted samples. Diagnostic performance for analysis of whole and skim milk was compared at cut-off values that achieved a desired operating characteristic of at least 95% specificity. For whole milk diluted 1:2 and a cut-off of 0.14 (S/P ratio), sensitivity and kappa values were 74.7% (95% CI 64.3-83.4) and 0.70 (95% CI 0.61-0.78), respectively. For skim milk diluted 1:2 and a cut-off of 0.30, sensitivity and kappa values were 77.0% (95% CI 66.8-85.4) and 0.72 (95% CI 0.64-0.80), respectively. Using the selected cut-offs, the IDEXX Neospora Ab Test is equally suited for the analysis of whole and skim milk as a screening tool in neosporosis control programs.
authors: Antel BioSystems, Inc., Lansing, MI 48909, United States. byremt@antelbio.com
authors: T M
authors: TM
authors: Byrem
authors: P C
authors: PC
authors: Bartlett
authors: H
authors: H
authors: Donohue
authors: B D
authors: BD
authors: Voisinet
authors: J T
authors: JT
authors: Houseman
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000032:analysis* / Q000097:blood; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000469:parasitology*; D003048:Coccidiosis / Q000175:diagnosis / Q000469:parasitology / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D007774:Lactation; D008892:Milk / Q000276:immunology*; D018688:Neospora / Q000276:immunology* / Q000302:isolation & purification; D011237:Predictive Value of Tests; D011247:Pregnancy; D015597:Pregnancy Complications, Parasitic / Q000175:diagnosis / Q000469:parasitology / Q000662:veterinary; D012372:ROC Curve; D011933:Reagent Kits, Diagnostic; D012015:Reference Standards; D012680:Sensitivity and Specificity; D016036:Seroepidemiologic Studies
chemical_list: D000913:Antibodies, Protozoan; D011933:Reagent Kits, Diagnostic