Abstract
Intradermal tuberculin testing is widely used for non-human primate Mycobacterium tuberculosis screening. The most commonly used tuberculin for screening, mammalian old tuberculin (MOT), shows high cross-reactivity due to its composition of poorly defined mycobacterial antigens.2 Frequent non-specific intradermal eyelid tuberculin responses have been observed in silvered leaf monkeys (Trachypithecus cristatus ultima) with confirmed negative status on ancillary testing at the Wildlife Conservation Society’s Bronx Zoo. A review of all individuals tested over a 10-year period (1998–2008) showed a 51.6% (16/31) period prevalence of non-specific intradermal eyelid tuberculin responses.
A rapid lateral flow test approved for use in Macaca spp. (PrimaTB STAT-PAK Assay®, Chembio Diagnostic Systems, Inc., Medford, NY 11763 USA) was employed to assess its utility for evaluation of non-specific tuberculin responses in langurs. This test utilizes a membrane-based antibody detection method for detection of antibodies against M. tuberculosis and M. bovis and is a host species-independent test. The test also did not cross-react with M. avium or M. kansasii inoculated rhesus macaques (Macaca mulatta).1
Serum or plasma samples from 16 silvered leaf monkeys (11 with non-specific tuberculin responses and five with negative tuberculin tests) were assessed. All suspect tuberculin responders received comparative tuberculin testing (either eyelid or chest) with avian old tuberculin or balanced PPD-avian and balanced PPD-bovis and the responses to these antigens indicated that they were non-specific responders. Six animals (four non-specific responders and two negative) died of unrelated causes and gross necropsy and histopathology demonstrated no evidence of granulomatous inflammation. Results of RT tests are listed in Table 1. These results suggest this assay may be a useful screening test to evaluate non-specific tuberculin responses in silvered leaf monkeys.
Table 1. Intradermal eyelid tuberculin test and rapid lateral flow test (RT) results for silvered leaf monkeys (Trachypithecus cristatus ultima) at the Wildlife Conservation Society’s Bronx Zoo
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Intradermal eyelid tuberculin test status
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Number of animals
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Number RT negative
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Number RT positive
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Number RT equivocal
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Non-specific tuberculin response
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11
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10
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0
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1
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Negative tuberculin response
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5
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4
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0
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1
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Acknowledgments
The authors thank Chembio Diagnostic Systems, Inc. and Centaur, Inc. for donation of RT test kits for use in the study. We additionally thank the efforts of the Wildlife Conservation Society’s Global Health Programs staff, especially Krysten Marchese, for their assistance and the Columbus Zoo and Omaha’s Henry Doorly Zoo for contribution of additional information.
Literature Cited
1. Lyashchenko, K.P., R. Greenwald, J. Esfandiari, D. Greenwald, C.A. Nacy, S. Gibson, P.J. Didier, M. Washington, P. Szczerba, S. Motzel, L. Handt, J.M. Pollock, J. McNair, P. Andersen, J.A.M. Langermans, F. Verreck, S. Ervin, F. Ervin, and C. McCombs. 2007. PrimaTB STAT-PAK Assay, a novel, rapid lateral-flow test for tuberculosis in nonhuman primates. Clin. Vaccine Immunol. 14: 1158–1164.
2. Fox, J.G., S.M. Niemi, and J.C. Murphy. 1982. A comparison of two tuberculins in nonsensitized macaques. J. Med. Primatol. 11: 380–388.