A 15-year-old male chimpanzee (Pan troglodytes) had a five-month history of intermittent lethargy, discharging inguinal wound, loss of body condition, and recent cough. Examination revealed multifocal purulent lymphadenitis, radiographic unilateral pulmonary interstitial alveolar infiltrate, neutrophilia, circulating myelocytes, metamyelocytes and promyelocytes, and acid-fast bacilli (AFB) on lymph node fine needle aspirates (FNA). TB Stat-Pak® (SP, Chembio) and Dual Path Platform Vet® TB test™ (DPP, Chembio) (retrospective) were reactive. PCR on FNA was positive for Mycobacterium tuberculosis complex DNA prompting euthanasia. Necropsy revealed pyogranulomatous pneumonia, pleuritis, lymphadenitis, splenitis, nephritis, peritonitis, enteritis, and hepatitis. Interferon gamma release assay (IGRA, Primagam®, Asure Quality) was positive. Culture confirmed M. tuberculosis. The genotype was identical to that from an Asian elephant (Elephas maximus) diagnosed with tuberculosis (TB) 12 months earlier, suggesting an epidemiologic link between the two cases.1,2
Seventeen chimpanzee cohorts were screened for TB using comparative tuberculin skin test (TST), IGRA, thoracic radiographs, SP, and tracheobronchial lavage (AFB smear, PCR, culture). Three of six TST positive animals were also IGRA positive. None had radiographic lesions consistent with TB; all were non-reactive on SP and negative on tracheobronchial testing. All commenced treatment with isoniazid and rifampicin. Rifampicin was successfully replaced with rifabutin where compliance was poor. Screening was repeated after four months. Six animals were considered latently infected (positive TST and/or IGRA) and remained on treatment for nine months. After completion of treatment, the six animals were retested. All tests were negative, apart from a young male that remained IGRA positive. All 17 animals were rescreened in 2013 and 2014. The young male remained IGRA positive; all other tests were negative and there was no evidence of TB disease in any animal.
We thank the Taronga primate team, Taronga Wildlife Hospital staff, Tammy McDonough, Guy Marks, and the many others who were involved and provided assistance.
1. Stephens N, Vogelnest L, Lowbridge C, Christensen A, Marks GB, Sintchenko V, McAnulty J. Transmission of Mycobacterium tuberculosis from an Asian elephant (Elephas maximus) to a chimpanzee (Pan troglodytes) and humans in an Australian zoo. Epidemiol Infect. 2013;141(7):1488–1497.
2. Vogelnest L, Hulst F, Thompson P, Lyashchenko KP, Vinette Herrin KA. Diagnosis and management of tuberculosis (Mycobacterium tuberculosis) in an Asian elephant (Elephas maximus) with a newborn calf. J Zoo Wildl Med. 2015;46(1):77–85.