Development of a diagnostic intradermal tuberculin test model for bovine tuberculosis

Abstract

Bovine tuberculosis caused by Mycobacterium bovis, is a chronic debilitating disease of mostly domestic cattle with infections reported in a wide range of domestic and wild animal species and also in humans. Due to its trade and public health implications, bovine tuberculosis is a controlled disease in many countries. The prescribed diagnostic test is the intradermal tuberculin test (skin test) which involves the evaluation of the host’s hypersensitivity reaction 72 hours after the intradermal injection of purified derivatives of mycobacterial proteins (bovine and avian tuberculin). Interpretation of skin test reactions is based on measuring the increase in skin thickness, as well as the subjective evaluation of any clinical signs observed such as edema and necrosis. The quality of the test outcome is highly dependent on the operator’s skills and experience in performing this test. Practical training of veterinary students in the correct execution and interpretation of the skin test is therefore a critical Day 1 competency. Live animal training for intradermal tuberculin testing is limited and no skin test models are commercially available. Therefore, bovine skin models made of dragon skin and platinum-cure silicon placed on aluminum clipper frames measuring 20x30cm and covered with artificial hair were developed. Each of the five models represents a different common test outcome: edema, diffuse or circumscribed swellings, necrosis and adhesion of the skin. The models are used to evaluate the different skin reactions by palpation, measuring skin thickness, and visual evaluation. A step-by-step manual is available to guide students through the procedure and interpretation of the skin reactions.