Tuberculosis (TB) in captive African rhinoceros has been sporadically reported.2 However, mycobacterial infection has only recently been observed in rhinoceros in range countries.1,3,5 Between 2016 and 2018, Mycobacterium bovis (M. bovis) infection was confirmed in one black and five white rhinoceros in Kruger National Park, South Africa. The South African Department of Agriculture, Forest, and Fisheries (DAFF) issued a quarantine notice in December 2016, which has prevented further rhinoceros translocations until a management plan could be created that included TB testing of rhinoceros. A novel interferon-gamma (IFN-γ) release assay (IGRA), based on the human QuantiFERON® TB Gold In-Tube (QFT) (Qiagen, Hilden, Germany) whole blood stimulation platform and a commercially available equine IFN-γ ELISA (Mabtech AB, Nacka Strand, Sweden) for cytokine detection, was developed and validated for use in black and white rhinoceros. Samples from known M. bovis infected and uninfected white rhinoceros were used to determine response kinetics and diagnostic cut-off value for the ELISA.4 Screening of free-ranging and boma-confined rhinoceros has detected individuals that have had consistent positive IGRA results on serial samples, suggesting that these may be infected and require further confirmatory testing. These preliminary findings indicate that this IGRA, using commercially available reagents, has promise as diagnostic tool to screen African rhinoceros for mycobacterial infection and facilitate future translocations, especially from TB endemic populations.
The authors would like to thank the following the individuals for their contributions to this study: Leana Rossouw, Guy Hausler, Tebogo Manamela, Dr. Markus Hofmeyr, Dr. Lin-Mari deKlerk-Lorist, Dr. Louis van Schalkwyk, and the Veterinary Wildlife Services capture team from Kruger National Park for assistance with sample collection from the rhinoceros. The authors also acknowledge Drs. Eva Gelius and Jens Gertow of Mabtech Ab for their assistance. This work was supported by the South African Medical Research Council, the National Research Foundation of South Africa [SARChI grant 86949], and the American Association of Zoo Veterinarians Wild Animal Health Fund. The content is the sole responsibility of the authors and does not necessarily represent the official views of the funders.
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