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===''Brachyspira'' and ''Serpulina''===
===''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 dysentry
**''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]]
[[Brachyspira hyodysenteriae]]