title: Evaluation of microbial culture of pooled fecal samples for detection of Mycobacterium avium subsp paratuberculosis in large dairy herds.
abstract: OBJECTIVE
  To evaluate sensitivity of microbial culture of pooled fecal samples for detection of Mycobacterium avium subsp paratuberculosis (MAP) in large dairy herds and assess the use of the method for estimation of MAP prevalence.
  
  
  METHODS
  1,740 lactating cows from 29 dairy herds in California.
  
  
  METHODS
  Serum from each cow was tested by use of a commercial ELISA kit. Individual fecal samples were cultured and used to create pooled fecal samples (10 randomly selected fecal samples/pool; 6 pooled samples/herd). Sensitivity of MAP detection was compared between Herrold's egg yolk (HEY) agar and a new liquid culture method. Bayesian methods were used to estimate true prevalence of MAP-infected cows and herd sensitivity.
  
  
  RESULTS
  Estimated sensitivity for pooled fecal samples among all herds was 0.69 (25 culture-positive pools/36 pools that were MAP positive). Sensitivity increased as the number of culture-positive samples in a pool increased. The HEY agar method detected more infected cows than the liquid culture method but had lower sensitivity for pooled fecal samples. Prevalence of MAP-infected cows was estimated to be 4% (95% probability interval, 2% to 6%) on the basis of culture of pooled fecal samples. Herd-level sensitivity estimate ranged from 90% to 100% and was dependent on prevalence in the population and the sensitivity for culture of pooled fecal samples.
  
  
  CONCLUSIONS
  Use of pooled fecal samples from 10 cows was a cost-effective tool for herd screening and may provide a good estimate of the percentage of MAP-infected cows in dairy herds with a low prevalence of MAP.
authors.affiliation: Departments of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Saraya
authors.initials: S
authors.lastname: Tavornpanich
authors.forename: Ian A
authors.initials: IA
authors.lastname: Gardner
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Anderson
authors.forename: Sang
authors.initials: S
authors.lastname: Shin
authors.forename: Robert H
authors.initials: RH
authors.lastname: Whitlock
authors.forename: Terry
authors.initials: T
authors.lastname: Fyock
authors.forename: John M
authors.initials: JM
authors.lastname: Adaska
authors.forename: Richard L
authors.initials: RL
authors.lastname: Walker
authors.forename: Sharon K
authors.initials: SK
authors.lastname: Hietala
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002140:California; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis / Q000382:microbiology*; D003470:Culture Media; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000382:microbiology*; D016927:Mycobacterium avium subsp. paratuberculosis / Q000302:isolation & purification*; D010283:Paratuberculosis / Q000175:diagnosis*; D015995:Prevalence; D012680:Sensitivity and Specificity
chemical_list: D003470:Culture Media