Rationale: Tuberculosis (TB) in elephants is a chronic respiratory disease, most often caused by Mycobacterium tuberculosis, and infected animals show little or no clinical sign until the disease is in its advanced stages. There are currently no validated diagnostic assays for TB in elephants and those currently used appear to have suboptimal sensitivity or specificity. This urges for the establishment of an affordable and sensitive diagnostic algorithm able to detect TB in elephants at an early stage.
Aim of the study: To determine the immune response profiles of fifty elephants using the DPP™VET TB Assay , ElephantTB Stat Pak®, PPD ELISA and Elephant specific IFN-_ assay assay and for their usefulness to diagnose tuberculosis in captive African elephants.
Study design: Fifty captive African elephants (Loxodonta africana) in six privately owned facilities in Victoria Falls (Northwestern Zimbabwe) and Livingstone (South Eastern Zambia) were sampled during the period September 2014. Follow up testing was done on 17 animals previously test positive for the Elephant specific IFN-_ assay in November 2015. Heparinised blood samples and serum from all elephants were tested using the Elephant specific IFN-_ assay, (stimulation was done with bovine and avian tuberculin as well recombinant antigens ESAT-6; CFP10 and positive and negative controls) and serological tests respectively. (ElephantTB Stat Pak® / DPP™VET TB Assay and PPD ELISA).
Results: The four different tests used in fifty elephants in this study during the period September-November 2014 indicated the following prevalences of immune reactivity to Mycobacterium tuberculosis complex Elephant specific IFN-_ assay: Elephant TB Stat Pak®: 36%; DPP™ VET TB Assay: 2%; 12% and PPD ELISA: 6%.