Submitted to: Clinical and Vaccine Immunology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/26/2009
Publication Date: 5/1/2009
Citation: Greenwald, R., Lyashchenko, O., Esfandiari, J., Miller, M., Mikota, S., Olsen, J.H., Ball, R., Dumonceaux, G., Schmitt, D., Moller, T., Payeur, J.B., Harris, B., Sofranko, D., Waters, W.R., Lyashchenko, K.P. 2009. Highly Accurate Antibody Assays for Early and Rapid Detection of Tuberculosis in African and Asian Elephants. Clinical and Vaccine Immunology. 16(5):605-612. Interpretive Summary: Tuberculosis is common in elephants in zoos, circuses, and wildlife parks within the United States. This infection represents a serious risk to elephant handlers; exhibit visitors, and other animals. At present, the only method to diagnose the infection is by culture of trunk wash samples. This method is exceedingly insensitive; thus, many infected elephants are not detected until very late in the course of disease. In the present study, it was determined that infected elephants produce antibodies to the bacterium and these antibodies are detectable by simple laboratory methods. Using this method of diagnosis, tuberculosis infection was diagnosed up to 4 years prior to the standard method of tuberculosis diagnosis of elephants (i.e., culture). Furthermore, it was determined that evaluation of antibody responses was a reliable method to evaluate the effectiveness of therapy to cure the disease. These findings will be useful for developing new strategies for surveillance of tuberculosis in elephants.
Technical Abstract: Tuberculosis (TB) in elephants is a re-emerging zoonotic disease caused primarily by Mycobacterium tuberculosis. Current methods for screening and diagnosis rely on trunk wash culture, which has serious limitations due to low test sensitivity, slow turn-around time, and variable sample quality. Innovative and more efficient diagnostic tools are urgently needed. We describe three novel serologic techniques, ElephantTB STAT-PAK kit, multiantigen print immunoassay (MAPIA), and dual path platform (DPP) VetTB test, for rapid detection of antibody in elephants. The study was performed with samples from 236 captive African and Asian elephants from 53 different locations in the US and Europe. The elephants were divided into three groups based on disease status and history of exposure: 1) 26 animals with culture-confirmed TB due to M. tuberculosis or M. bovis, 2) 63 exposed elephants from different infected herds which had never produced a culture positive result from trunk wash samples, and 3) 147 elephants with no clinical symptoms suggestive of TB, with consistently negative trunk wash culture results, and with no history of potential exposure to TB in the past 5 years. Elephants with culture-confirmed TB and a proportion of exposed but trunk wash TB culture negative elephants produced robust antibody responses to multiple antigens of M. tuberculosis, with seroconversions detectable years before TB positive cultures from trunk wash specimens. ESAT-6 and CFP10 proteins were immunodominant antigens recognized by elephant IgG. The serologic assays demonstrated 100% sensitivity and 95-100% specificity. Use of rapid and accurate serologic assays to identify infected elephants will likely allow earlier and more efficient treatment, thus limiting transmission of infection to other susceptible animals and humans.