From: Measuring antigen-specific responses in Mycobacterium bovis-infected warthogs (Phacochoerus africanus) using the intradermal tuberculin test
Skinfold reading
Culture Positive
Culture Negative
Δ PPDa
0.2 mm (−0.1–0.5)
0.3 mm (−0.2–0.7)
Δ PPDb
3.0 mm (0.9–4.0)
0.0 mm (−0.1–0.6)
PPDb - PPDa
2.5 mm (1.3–3.5)
-0.4 mm (− 0.5–0.1)