Swine dysentery: protection against experimental challenge following single dose parenteral immunisation with inactivated Treponema hyodysenteriae.

Groups of five pigs were vaccinated at three to four weeks old with either formolised Treponema hyodysenteriae in oil adjuvant alone, formolised T hyodysenteriae in oil adjuvant plus formolised Campylobacter coli in oil adjuvant, or sterile medium in oil adjuvant (as a control). Each group was challenged four weeks after vaccination by oral dosing on two consecutive occasions with pure cultures of the homologous strain of T hyodysenteriae plus direct contact with two pigs exhibiting severe swine dysentery. The disease was observed in two of five pigs immunised with T hyodysenteriae alone, three of five pigs immunised with T hyodysenteriae plus C coli and all five controls; haemorrhagic diarrhoea was exhibited only by the control group. Each pig immunised with T hyodysenteriae (alone or with C coli) recovered spontaneously, whereas four controls died. Vaccination with T hyodysenteriae also markedly reduced the severity and duration of clinical signs and of weight loss. No differences were observed in response to challenge between pigs immunised with T hyodysenteriae alone and pigs immunised with T hyodysenteriae plus C coli.