In their latest paper in BMC Veterinary Research, Ken Pedersen of the Centre for Herd oriented Education, Research and Development at the University of Copenhagen and co-authors at the Technical University of Denmark and Universidade Federal de Minas Gerais in Brazil describe their study to investigate the correlation between histological findings of Lawsonia intracellularis in porcine cases of diarrhoea and the quantitative detection of L.intracellularis in faeces.

Explaining the background to the work, the researchers state that antibiotic use for livestock has increasing concern in relation to development of antimicrobial resistance in both animals and humans. In Denmark, half of the antibiotics used in pigs are to treat diarrhoea from all causes, which include L.intracellularis. Development of quantitative PCR (qPCR) tests for quantification of this bacterium in faeces is now routine basis and may be useful for confirmation of L. intracellularis as the microbiological cause in porcine diarrhoea. Correlation between disease severity and excretion load for a specific pathogen could be expected but is not always demonstrated and the relationship was investigated in this Danish work.

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 L.intracellularis by real-time PCR.

The median L.intracellularis excretion was significantly higher in pigs with gross lesions of proliferative enteropathy (median excretion: 5.92 log₁₀ bacteria per gramme of faeces) compared to pigs without gross lesions of proliferative enteropathy (median excretion: <3.3 log₁₀ bacteria per gramme of faeces; P<0.001).

Spearman's correlation coefficient between the measurable proliferative enteropathy lesions and L.intracellularis excretion was 0.50 (P<0.001). A significantly increasing trend in L.intracellularis excretion level for increasing proliferative enteropathy histopathology and immunohistochemistry scores was demonstrated (P<0.001 and P<0.001, repsectively).

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).

Pedersen and co-authors concluded that the histological and quantitative PCR detection of L.intracellularis were correlated in pigs with diarrhoea. Overall, the results suggest that clinically important levels for L.intracellularis excretion in faeces may be established, they continued. Such clinical threshold levels may be used in practice to confirm a diagnosis of L.intracellularis-associated diarrhoea.

Reference

Pedersen K.S., M. Stahl, R.M.C. Guedes, Ø. Angen, J.P. Nielsen and T.K. Jensen. 2012. Association between faecal load of Lawsonia intracellularis and pathological findings of proliferative enteropathy in pigs with diarrhoea. BMC Veterinary Research, 8:198. doi:10.1186/1746-6148-8-198

Further Reading You can view the full report (as a provisional PDF) by clicking here. Find out more information on proliferative enteropathy (ileitis) by clicking here.