title: Detection of Mycobacterium avium subspecies paratuberculosis specific IS900 insertion sequences in bulk-tank milk samples obtained from different regions throughout Switzerland.
abstract: BACKGROUND
  Since Mycobacterium avium subspecies paratuberculosis (MAP) was isolated from intestinal tissue of a human patient suffering Crohn's disease, a controversial discussion exists whether MAP have a role in the etiology of Crohn's disease or not. Raw milk may be a potential vehicle for the transmission of MAP to human population. In a previous paper, we have demonstrated that MAP are found in raw milk samples obtained from a defined region in Switzerland. The aim of this work is to collect data about the prevalence of MAP specific IS900 insertion sequence in bulk-tank milk samples in different regions of Switzerland. Furthermore, we examined eventual correlation between the presence of MAP and the somatic cell counts, the total colony counts and the presence of Enterobacteriaceae.
  
  
  RESULTS
  273 (19.7%) of the 1384 examined bulk-tank milk samples tested IS900 PCR-positive. The prevalence, however, in the different regions of Switzerland shows significant differences and ranged from 1.7% to 49.2%. Furthermore, there were no statistically significant (p >> 0.05) differences between the somatic cell counts and the total colony counts of PCR-positive and PCR-negative milk samples. Enterobacteriaceae occur as often in IS900 PCR-positive as in PCR-negative milk samples.
  
  
  CONCLUSIONS
  This is the first study, which investigates the prevalence of MAP in bulk-tank milk samples all over Switzerland and infers the herd-level prevalence of MAP infection in dairy herds. The prevalence of 19.7% IS900 PCR-positive bulk-milk samples shows a wide distribution of subclinical MAP-infections in dairy stock in Switzerland. MAP can therefore often be transmitted to humans by raw milk consumption.
authors.affiliation: Institute for Food Safety and Hygiene, Faculty of Veterinary Medicine, University of Zurich, Winterthurerstrasse 270, CH-8057 Zurich, Switzerland. scorti@gmx.net
authors.forename: Sabrina
authors.initials: S
authors.lastname: Corti
authors.forename: Roger
authors.initials: R
authors.lastname: Stephan
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004755:Enterobacteriaceae / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000175:diagnosis / Q000453:epidemiology / Q000635:transmission / Q000662:veterinary; D005798:Genes, Bacterial / Q000235:genetics; D006801:Humans; D008892:Milk / Q000737:chemistry / Q000166:cytology / Q000382:microbiology*; D016254:Mutagenesis, Insertional / Q000235:genetics; D009162:Mycobacterium avium / Q000235:genetics* / Q000302:isolation & purification*; D016927:Mycobacterium avium subsp. paratuberculosis / Q000235:genetics* / Q000302:isolation & purification*; D021141:Nucleic Acid Amplification Techniques; D010283:Paratuberculosis / Q000175:diagnosis / Q000453:epidemiology / Q000635:transmission; D016133:Polymerase Chain Reaction / Q000379:methods; D015995:Prevalence; D013045:Species Specificity; D013557:Switzerland / Q000453:epidemiology
chemical_list: D004269:DNA, Bacterial