title: Association between faecal load of lawsonia intracellularis and pathological findings of proliferative enteropathy in pigs with diarrhoea.
abstract: BACKGROUND
  The study was designed to investigate correlation between histological findings of Lawsonia intracellularis in porcine cases of diarrhoea and the quantitative detection of Lawsonia intracellularis in faeces. A total of 156 pigs (10 to 70 days post weaning) with diarrhoea were randomly selected from 20 herds: The pigs were subjected to necropsy, histopathology, immunohistochemistry and faecal quantification of Lawsonia intracellularis by real time PCR.
  
  
  RESULTS
  The median Lawsonia intracellularis excretion was significantly higher in pigs with gross lesions of proliferative enteropathy (median excretion: 5.92 log10 bacteria/g faeces) compared to pigs without gross lesions of proliferative enteropathy (median excretion: <3.3 log10 bacteria/g faeces) (P<0.001). Spearman's correlation coefficient between the measureable PE lesions and L. intracellularis excretion was 0.50 (P<0.001). A significantly increasing trend in Lawsonia intracellularis excretion level for increasing proliferative enteropathy histopathology and immunohistochemistry scores was demonstrated (P<0.001; P<0.001). Spearman's correlation coefficient between the histopathology scores and L. intracellularis excretion was 0.67 (P<0.001). Spearman's correlation coefficient between the IHC scores and L. intracellularis excretion was 0.77 (P<0.001).
  
  
  CONCLUSIONS
  The histological and quantitative PCR detection of Lawsonia intracellularis were correlated in pigs with diarrhoea. Overall the results suggest that clinically important levels for Lawsonia intracellularis excretion in faeces may be established. Such clinical threshold levels may be used in practice to confirm a diagnosis of Lawsonia intracellularis associated diarrhoea.
authors.affiliation: HERD - Centre for Herd oriented Education, Research and Development, Department of Large Animal Sciences, University of Copenhagen, Groennegaardsvej 2, Frederiksberg C 1870, Denmark. ken@life.ku.dk
authors.forename: Ken Steen
authors.initials: KS
authors.lastname: Pedersen
authors.forename: Marie
authors.initials: M
authors.lastname: Ståhl
authors.forename: Roberto Maurício Carvalho
authors.initials: RM
authors.lastname: Guedes
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Angen
authors.forename: Jens Peter
authors.initials: JP
authors.lastname: Nielsen
authors.forename: Tim K
authors.initials: TK
authors.lastname: Jensen
mesh_terms: D000818:Animals; D045824:Desulfovibrionaceae Infections / Q000382:microbiology / Q000662:veterinary*; D004196:Disease Outbreaks / Q000662:veterinary; D004751:Enteritis / Q000382:microbiology / Q000662:veterinary*; D005243:Feces / Q000382:microbiology*; D007150:Immunohistochemistry; D020639:Lawsonia Bacteria / Q000302:isolation & purification*; D013552:Swine