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Unexpected high responses to tuberculin skin-test in farmed red deer: implications for tuberculosis control


May 1st, 2012

Preventive Veterinary Medicine publish this investigation article


Tuberculosis (TB) in deer is a serious zoonotic disease of worldwide distribution. Detection of infected animals is usually performed using single or comparative skin testing (SST/CST), although false responses due to sensitization to other mycobacteria may occur, hampering diagnostic specificity. We describe the evolution of the responses to the SST, CST and to an in-house serological assay in a red deer farm subjected to regular TB testing in southern Spain in an attempt to understand the dynamics of possible non-specific reactions occurring under field conditions. We performed 2288 skin-tests and ELISA assays in nine sampling periods between May 2009 and January 2011. In May 2010, a strong increase in skin fold thickness in response to avian purified protein derivative (PPD) (mean=4.0 mm, 95% CI=3.5-4.5) and bovine PPD (mean=1.8 mm, 95% CI=1.6-2.0) was observed in yearling deer hinds (n=150), compared to values recorded for the same individuals in November 2009 (avian PPD: mean=0.7 mm, 95% CI=0.6-0.8 and bovine PPD: mean=0.7mm, 95% CI=0.6-0.7) and in January 2011 (avian PPD: mean=2.2 mm, 95% CI=1.9-2.4 and bovine PPD: mean=1.1 mm, 95% CI=1.0-1.2). Using SST, 54 animals (36%) of the yearlings tested in May 2010 would have been classified as positive reactors, while none of them was positive in the CST. The five animals with highest skin fold increases to mycobacterial antigens were culled and subjected to post-mortem analysis, which confirmed the absence of Mycobacterium tuberculosis complex (MTBC) infection but demonstrated the presence of environmental mycobacteria and closely related bacteria in four out of the five analyzed animals. Our results demonstrated how non-specific responses to mycobacterial antigens can adversely affect the specificity of TB diagnosis based on the SST. Thus, once TB infection has been ruled out using confirmatory techniques, application of 3 comparative diagnostic tests is highly advisable 48 to maximize test specificity and avoid the slaughter of false positive reactors




Queiros J., Alvarez J., Carta T., Mateos A., Ortiz JA., Fernandez de Mera IG., Martin-Hernando MP. and Gortazar C.




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Unexpected high responses to tuberculin skin-test in farmed red deer: implications for tuberculosis control

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Unexpected high responses to tuberculin skin-test in farmed red deer: implications for tuberculosis control





Preventive Veterinary Medicine
FACTOR YEAR Q
2.389 2012

NLMID: 8217463

PMID: 22197268

ISSN: 0167-5877



TITLE: Unexpected high responses to tuberculin skin-test in farmed red deer: implications for tuberculosis control


JOURNAL: Prev. Vet. Med.


NUMERACIÓN: 104(3-4):327-34


AÑO: 2012


PUBLISHER: Elsevier Science Publishers


AUTHORS: Queiros J., Alvarez J., Carta T., Mateos A., Ortiz JA., Fernandez de Mera IG., Martin-Hernando MP. and Gortazar C.


DOI: http://dx.doi.org/ 10.1016/j.prevetmed.2011.11.009


CITE THIS PUBLICATION:

Queiros J., Alvarez J., Carta T., Mateos A., Ortiz JA., Fernandez de Mera IG., Martin-Hernando MP. and Gortazar C.. Unexpected high responses to tuberculin skin-test in farmed red deer: implications for tuberculosis control . Preventive Veterinary Medicine. 104(3-4):327-34. 2012. ISSN: 0167-5877. DOI: 10.1016/j.prevetmed.2011.11.009