First description of concomitant infection with tuberculosis and paratuberculosis in dairy sheep in Argentina

The authors present the results of a comparative intradermal tuberculin tes t performed on dairy sheep to determine rates of reaction to bovine and avi an purified protein derivative(PPD), Test reactions were interpreted by pal pation and measurement with a calliper, Results were analysed by plotting t he values obtained, Agar gel immunodiffusion tests, growth in culture and h istopathological examinations were also performed to allow differential dia gnosis between tuberculosis and paratuberculosis. In the first tuberculin t est, performed on 288 sheep, 74 animals showed a positive reaction to avian PPD (25.69%), two animals showed a positive reaction to bovine PPD (0.69%) , and one animal was positive with respect to both tuberculins (0.34%). in the second test, involving 247 sheep, 55 demonstrated a positive reaction t o avian PPD (22.26%), whilst none reacted to bovine PPD. The presence of My cobacterium avium su bsp. paratuberculosis was confirmed by culture and ser ological testing. In addition, lesions compatible with those caused by IM. bovis were found by histopathological examination. These findings highlight the importance of the accurate diagnosis of tuberculosis and paratuberculo sis for the effective control of both diseases.