Category:Spirochaetaceae

<ncl style=compact maxdepth=2 headings=bullet headstart=2 showcats=1 showarts=1>Category:Spirochaetaceae</ncl>

Borrelia

Brachyspira and Serpulina

• Anaerobic, intestinal spirochaetes, found in normal and diseased pigs
• Enterophogens of pigs
• B. hyodysenteriae, B. pilosicoli, B. innocens, Serpulina intermedia and S. murdochii occur in pigs
• Carrier pigs shed B. hyodysenteriae for up to 3 months, acting as a source of infection for healthy pigs
• Demonstrated in stained faecal smears or silver-stained histopathology sections
• Cultured anaerobically on selective blood agar
• Spirochaetes differentiated by pattern of haemolysis on blood agar as well as molecular techniques

• Pathogenesis
  • Motility in mucous allows colonisation of pig intestine
  • Haemolytic and cytotoxic activiity important for virulence
  • Attachment of B. pilosicoli to epithelial cells of colonic mucosa disrupts their function and leads to their shedding and oedema

• Clinical infections
  • B. hyodysenteriae causes swine dysentery
  • B. pilosicoli causes porcine intestinal spirochaetosis
  • Infection is acquired via contaminated faeces
  • Disease spreads slowly through the herd
  • Dogs, rats, mice and flies may act as transport hosts
  • B. hyodysenteriae survives several weeks in moist faeces

• Clinical signs
  • B. hyodysenteriae causes dysentry in weaned pigs 6-12 weeks old; pigs lose condition and become emaciated; appetite is decreased; large amount of mucous may be present in the faeces; low mortality; poor feed conversion ratio
  • B. pilosicoli causes less severe signs than swine dysentry; reduced feed conversion rates occur

• Diagnosis
  • History, clinical signs and gross pathology
  • Anaerobic culture on blood agar with added antibiotics for at least 3 days
  • B. hyodysenteriae causes complete haemolysis whereas other spirochaetes cause partial haemolysis
  • Immunofluorescence, DNA probes and biochemical tests
  • Serology using ELISA can be used on a herd basis
  • PCR

Brachyspira hyodysenteriae