Diagnosis of porcine proliferative enteropathies in pigs:: a comparison of different methods for the detection of Lawsonia intracellularis

Different techniques (modified Ziehl-Neelsen staining, in situ hybridization and PCR) were tested for the detection of Lawsonia intracellularis in pigs and by indirect immunofluorescent antibody test (IFAT) for L. intracellularis-specific antibodies. In 65 pigs with diarrhea PCR turned out to be the most sensitive method (31% positive samples) followed by in situ hybridization (23% positive samples) and modified Ziehl-Neelsen staining (17% positive samples). 46% of the animals had antibodies against L. intracellularis. 580 animals derived from 47 L. intracellularis-positive herds were tested by PCR from faecal samples and by IFAT from serum samples. Shedding of bacteria was found in 18.6% of the pigs and 51.4% were positive in IFAT. IFAT can be used for herd screening, but interpretation of serological results should be carried out under consideration of results from detection of the agent.