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== Introduction ==

== Introduction ==

Swine dysentery is an infectious disease caused by the anaerobic spirochete, ''Brachyspira hyodysenteriae'', seen in pigs worldwide. It causes a severe mucohaemorrhagic colitis of pigs, causing dysentry with variable amounts of mucous and necrotic material passed in the faeces. It is quite prevalent in the United Kingdom and can be important economically.

Swine dysentery is an infectious disease caused by the anaerobic spirochete, ''Brachyspira hyodysenteriae'', seen in pigs worldwide. It causes a severe mucohaemorrhagic colitis of pigs, causing dysentry with variable amounts of mucous and necrotic material passed in the faeces. It is quite prevalent in the United Kingdom and can be important economically. Recently new isolates called ''Brachyspira hampsonii'' have been isolated in the United States that are genetically distinct, but have strong hemolysis and are associated with clinical cases of dysentery. 

The disease is not systemic and is localised to the large intestine only - in particular, the spiral colon. It predominantly affects pigs post weaning, at around 4 months of age, but all the herd will show signs of the disease. It can be particularly severe in sows mid - late lactation. If a herd becomes infected there is usually around 90% morbidity and 50% mortality.

The disease is not systemic and is localised to the large intestine only - in particular, the spiral colon. It predominantly affects pigs post weaning, at around 4 months of age, but all the herd will show signs of the disease. It can be particularly severe in sows mid - late lactation. If a herd becomes infected there is usually around 90% morbidity and 50% mortality.