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

Table 3 Clinical signs and gross lesions in the caecum and colon at pm 49 days after exposure in the pigs in experiment 1

Pig group	Pig number	Clinical signs^a	Lesions observed at pm^b		Culture^c
Pig group	Pig number	Clinical signs^a	Caecum	Colon	Caecum	Colon	Faeces
A	1	0	[0]	[0]	0	1	1
	2	0	[1] (patchy)	[2] (patchy, upper 1/3)	0	1	2
	3	0	[0]	[0]	0	1	0
	4	0	[0]	[0]	0	1	0
	5	0	[0]	[0]	0	1	1
	6	0	[0]	[0]	1	1	1
	7	0	[0]	[0]	0	1	0
	8	0	[0]	[0]	0	1	0
	9	0	[1] (patchy)	[2] (patchy, upper 1/3)	0	1	1
	10	0	[0]	[0]	0	1	0
Median^d		0	0**	0	0**	1**	0**
B	11	1	[3]	[2] (localised, upper 1/3)	4	5	4
	12	0	[0]	[0]	1	3	1
	13	0	[0]	[0]	0	3	1
	14	1	[3]	[2] (localised, upper 1/3)	5	5	5
	15	0	[2]	[0]	3	3	1
	16	0	[2]	[0]	3	4	2
	17	1	[3]	[2] (localised, upper 1/3)	5	5	4
	18	1	[4]	[3] (upper 1/3)	5	5	5
	19	0	[3]	[0]	5	5	4
	20	1	[3]	[2] (localised, upper 1/3)	5	5	4
Median^d		0.5	3**	1	4.5**	4.5**	4**

Pigs in group A were inoculated with weakly haemolytic B. hyodysenteriae strain MU1 and those in group B were challenged with a strongly haemolytic field strain NSW54 isolated from a pig with SD.
^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