An atypical weakly haemolytic strain of Brachyspira hyodysenteriae is avirulent and can be used to protect pigs from developing swine dysentery

Table 8 Clinical signs and gross lesions observed at pm in the caecum and colons of pigs from experiment 3

Group number	Pig number	Clinical signs^a	Lesions observed at pm^b		Culture^c			Haemolysis (colon)	Identified strain
Group number	Pig number	Clinical signs^a	Caecum	Colon	Caecum	Colon	Faeces	Haemolysis (colon)	Identified strain
A	1	1	[0]	[3]	0	3	3	Strong	BW1
	2	0	[0]	[0]	0	2	0	Weak	MU1
	3	0	[0]	[0]	0	0	0	–	–
	4	0	[0]	[0]	0	1	0	Weak	MU1
	5	0	[0]	[0]	0	1	0	Weak	MU1
	6	0	[0]	[1]	0	1	0	Strong	WA1
	7	0	[0]	[0]	0	0	0	–	–
	8	0	[0]	[0]	0	0	0	–	–
	9	0	[0]	[0]	0	0	0	–	–
	10	0	[0]	[2]	0	2	0	Strong	BW1
	11	0	[0]	[0]	0	1	0	Weak	MU1
	12	0	[0]	[0]	0	0	0	–	–
Median^d		0**	0	0**	0	1**	0**
B	13	3	[0]	[2]	0	5	5	Strong	Vic 2
	14	3	[1]	[4]	3	5	5	Strong	BW1
	15	3	[1]	[3]	1	5	5	Strong	WA1
	16	3	[0]	[3]	0	5	5	Strong	Vic 2
	17	3	[0]	[3]	0	5	5	Strong	BW1
	18	3	[1]	[4]	1	5	5	Strong	NSW 5
	19	0	[0]	[0]	0	0	0	–	–
	20	3	[0]	[3]	0	1	5	Strong	BW1
	21	0	[0]	[0]	0	0	0	–	–
	22	1	[0]	[3]	0	5	5	Strong	WA1
	23	3	[1]	[4]	0	5	5	Strong	Vic 2
	24	3	[1]	[4]	4	5	5	Strong	NSW 5
Median^d		3**	0	3**	0	5**	5**

Group A was exposed to MU1 and subsequently challenged with a mixture of five virulent field strains of B. hyodysenteriae. Group B was only challenged with the virulent isolates.
^aClinical signs: 0, normal; 1, diarrhoea; 2, diarrhoea with mucus; 3, dysentery.
^bLesion scores: [0] normal; [1] mild localised erythema; [2] mild superficial erosions; [3] moderate superficial erosions; [4] severe erosions with mucus and fresh blood.
^cCulture score: 1 to 5, extent of growth on selective agar plates; 0, no growth.
^dMedians for the values in groups A and B that are significantly different in a Mann–Whitney test are marked with asterisks (* p = 0.05; ** p = 0.01).

ISSN: 1297-9716