VMC 221: Veterinary Immunology and Serology (1+1)

Single intradermal testing (SID)

SINGLE INTRADERMAL TEST (SID)

• 0.05 ml of PPD tuberculin from Mycobacterium tuberculosis or M. bovis is injected intradermally into one anal fold.
• After 72 to 96 hours a comparison is made between injected and uninjected folds and a positive reaction consists of a diffuse hard lump.
• The injection can also be given into the mucocutaneous junction of the vulva and side of neck. In latter case, it is more sensitive but restraint of the animal is difficult.

• Advantage: simple test.
• Disadvantages
  • Cannot distinguish infection by other mycobacteria such as M. avium or M. paratuberculosis or Nocardia.
  • False positive results may be due to exposure to M. phlei.
  • False negative in advanced tuberculosis, early infection, in animals calved within the preceding 4-6 weeks, very old cows and in animals tested within the preceding 1-10 weeks.