Detection of Brachyspira hyodysenteriae, Lawsonia intracellularis and Brachyspira pilosicoli in feral pigs.

Feral pigs are recognized as being a potential reservoir of pathogenic microorganisms that can infect domestic pigs and other species. The aim of this study was to investigate whether feral pigs in Western Australia were colonized by the pathogenic enteric bacteria Lawsonia intracellularis, Brachyspira hyodysenteriae and/or Brachyspira pilosicoli. A total of 222 feral pigs from three study-populations were sampled. DNA was extracted from faeces or colonic contents and subjected to a previously described multiplex PCR for the three pathogenic bacterial species. A subset of 61 samples was cultured for Brachyspira species. A total of 42 (18.9%) of the 222 samples were PCR positive for L. intracellularis, 18 (8.1%) for B. hyodysenteriae and 1 (0.45%) for B. pilosicoli. Four samples were positive for both L. intracellularis and B. hyodysenteriae. Samples positive for the latter two pathogens were found in pigs from all three study-sites. A strongly haemolytic B. hyodysenteriae isolate was recovered from one of the 61 cultured samples. Comparison of a 1250-base pair region of the 16S rRNA gene amplified from DNA extracted from the isolate and five of the B. hyodysenteriae PCR positive faecal samples helped confirm these as being from B. hyodysenteriae. This is the first time that B. hyodysenteriae has been detected in feral pigs. As these animals range over considerable distances, they present a potential source of B. hyodysenteriae for any domesticated pigs with which they may come into contact.