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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Infectious Bacterial Diseases Research » Research » Publications at this Location » Publication #198080


item LARSEN, R
item Waters, Wade

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/21/2006
Publication Date: 10/21/2006
Citation: Dumonceaux, G., Miller, M., Lyashchenko, K., Larsen, R.S., Waters, W.R., Kaufman, G. 2006. Tuberculosis in Elephants: An Update on Diagnosis and Treatment; Implications for Control in Range Countries [abstract]. In: Proceedings of the International Elephant Foundation. 2006 International Elephant Conservation and Research Symposium, October 21-22, 2006, Copenhagen, Denmark. 2006 CDROM

Interpretive Summary:

Technical Abstract: Tuberculosis has been detected in captive elephants in the U.S. and Europe (Lewerin 2005; Mikota 2000, 2001; Moller 2005). Culture of samples collected by a trunk wash procedure is the current method of diagnosis. Culture has inherent limitations as a primary diagnostic technique. Failure to isolate the organism does not rule out infection. Reporting time is slow as mycobacteria may require up to 8 weeks for isolation. Culture (requiring 3 samples from each elephant) is neither a practical nor affordable method to screen large numbers of elephants in Asia where surveillance is urgently needed. Alternative diagnostic tests currently under investigation include an ELISA (Larsen, University of California, Davis, California, USA), the ElephantTB STAT-PAK™ and Multi-Antigen Print Immunoassay (Lyashchenko, Chembio Diagnostic Systems, Inc., Medford, New York, USA), and an immunoblot assay (Waters, National Animal Disease Center, Ames, Iowas, USA). These assays detect the presence of antibody in elephant serum to antigens of Mycobacterium tuberculosis, and shared antigens of Mycobacterium bovis. Preliminary data suggest that serological tests may be accurate and early detectors of mycobacterial infection. The ELISA measures antibodies against specific antigens. A study using a six-antigen ELISA demonstrated an estimated sensitivity of 100% and specificity of 95%, on a limited sample size of 47 Asian and African elephants that included 7 culture positive cases (Larsen 2000). A modified version of this ELISA, with increased numbers of positive and negative Asian elephants, has so far had a similar specificity and sensitivity (unpublished, Dr. Scott Larsen). The ElephantTB STAT-PAK incorporates a unique cocktail of recombinant mycobacterial antigens impregnated on a nitrocellulose membrane and placed in a plastic cassette similar to a pregnancy test kit. Serum, plasma, or whole blood may be used and results are available in 20 minutes (Lyashchenko 2006). The Multi-Antigen Print Immunoassay (MAPIA) is a laboratory procedure for antibody detection that uses a panel of multiple recombinant antigens of M. tuberculosis and M. bovis that are separately applied to a nitrocellulose membrane using an automated printing device (Lyashchenko 2000). Elephant serum samples are incubated with a MAPIA strip and antigen-bound antibodies are visualized using a specific IgG-binding enzyme conjugate and corresponding substrate. To date 99 Asian and 72 African elephants in Europe, Australia, South Africa, and the U.S. have been tested using the RT and MAPIA. These included 21 elephants with TB confirmed by culture. Preliminary data has demonstrated a 100% sensitivity and 97% specificity for the RT and a 100% sensitivity and 100% specificity for the MAPIA using culture as the reference standard. Seroconversions have been noted in several elephants months to years prior to a positive culture (Lyashchenko 2006). The ElephantTB STAT-PAK™ is undergoing licensing procedures in the U.S. and will likely be available for commercial use in early 2007. Immunoblot detects antibodies to bacterial antigens that appear as discrete bands on a nitrocellulose membrane following electrophoresis. Experimentally, immunoblot detected antibody responses to a M. bovis whole cell sonicate in TB-infected elephants four years prior to culture of M. tuberculosis from trunk washes (personal communication, Dr. Ray Waters, NADC, USDA). Additionally, a biosensor (a breathalyzer) that detects the TB organism is under investigation for application to elephants. If effective it could be used in conjunction with serological tests to identify actively shedding animals. We have initiated TB testing of elephants in Nepal and India and the commercial availability of the RT will open the door to testing in other range countries. Developing effective disease management strateg