Different lesion distribution in calves orally or intratracheally challenged with Mycobacterium bovis: implications for diagnosis

Table 1 Results for IGRA and skin tuberculin tests performed

Group	ID	IGRA test						Skin test
		Weeks after challenge						Δ (mm) skin thickness			Interpretation
		0	2	4	8	12	20	PPD-A	PPD-B	PPD-B–PPD-A	SIT	CIT
EC	1	N	P	P	P	P	—	1	5	4	P	I
	2	N	P	P	P	P	—	1	12	11	P	P
	3	N	P	P	P	N^a	—	1	8	7	P	P
	4	N	P	P	P	P	—	0	9	9	P	P
	5	N	P	P	P	P	—	2	9	7	P	P
OC	6	N	N	N	P	P	—	3	16	13	P	P
	7	N	N	N	P	N^b	—	9	22	13	P	P
	8	N	N	P	P	N^c	P	3	10	7	P	P
	9	N	N	P	P	P	P	2	8	6	P	P
	10	N	N	P	P	P	P	5	17	12	P	P

SIT: Single Intradermal Test, CIT: Comparative Intradermal Test, EC: endotracheally challenged, OC: orally challenged, Δ: increase, A-PPD: avian PPD, B-PPD: bovine PPD, P: positive, I: inconclusive, N: negative.
^a IDscreen S/P% = 28.06.
^b IDscreen S/P% = 20.17.
^c IDscreen S/P% = 22.26.
—: these animals were necropsied 12 weeks after challenge. The remaining three were tested for IGRA once more before being necropsied 20 weeks after challenge.

ISSN: 1297-9716