title: Comparison of subjective and objective test evaluations for use of Mycobacterium phlei-adsorbed serum in a dot-enzyme-linked immunosorbent assay for diagnosis of paratuberculosis in cattle.
abstract: Use of a dot-ELISA with serum adsorbed with Mycobacterium phlei or with nonadsorbed serum was compared. In addition, results attained using visual observation were compared with those obtained using a densitometer. Infection status of cattle was determined by results of culture of feces from a number of cattle with various degrees of exposure (low prevalence and test-negative) and disease manifestation (clinical suspect vs subclinical infection). Two paratuberculosis-negative herds, fecal culture-confirmed clinically suspect cases of paratuberculosis, and cows from 2 paratuberculosis-infected herds with diagnosis confirmed on the farm (low infection rate) were tested. Significant (P less than 0.05) increase in the dot-ELISA response was found in cattle with heavy M paratuberculosis shedding when nonadsorbed and adsorbed sera were used, compared with the response in cattle that were fecal culture-negative or were shedding M paratuberculosis at lower amounts. Paratuberculosis was diagnosed by visual determination in 29 of 44 (65.9%) of fecal culture-positive, clinically suspect cattle when nonadsorbed serum was used. Results of the visual test were negative in 85 of 93 (91.4%) of the fecal culture-negative cattle when nonadsorbed serum was used. However, when using M phlei-adsorbed serum, the sensitivity of the visual determination decreased to 34.1% (15/44), and the specificity increased to 97.8% (91/93).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: National Veterinary Laboratory, Copenhagen, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Bech-Nielsen
authors.forename: W P
authors.initials: WP
authors.lastname: Shulaw
authors.forename: P L
authors.initials: PL
authors.lastname: Frandsen
authors.forename: J B
authors.initials: JB
authors.lastname: Jorgensen
authors.forename: N C
authors.initials: NC
authors.lastname: Feld
authors.forename: P
authors.initials: P
authors.lastname: Ahrens
mesh_terms: D000327:Adsorption; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis*; D003720:Densitometry; D003936:Diagnosis, Computer-Assisted / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000382:microbiology; D008838:Microcomputers; D016927:Mycobacterium avium subsp. paratuberculosis / Q000276:immunology* / Q000302:isolation & purification; D009168:Mycobacterium phlei; D010283:Paratuberculosis / Q000175:diagnosis*; D012680:Sensitivity and Specificity; D012984:Software
chemical_list: D000907:Antibodies, Bacterial