Abstract:
This study reports on an investigation of Mycobacterium tuberculosis cases in
mostly captive wild animals using molecular typing tools [Variable Number of
Tandem Repeat (VNTR) typing and Restriction Fragment Length Polymorphism
typing]. The investigation included cases from (i) the National Zoological
Gardens of South Africa (NZG) recorded between 2002 and 2011; (ii) Johannesburg
Zoo, where tuberculosis was first diagnosed in 2007 and has since been
detected in three antelope species; (iii) a rehabilitation centre for vervet monkeys
(Chlorocebus pygerythrus) in which M. tuberculosis was diagnosed in 2008; and
(iv) incidental cases in other facilities including a sable antelope (Hippotragus
niger), two unrelated cases in chacma baboons (Papio ursinus) (one of which was
from a free-ranging troop) and a colony of capuchin monkeys (Cebus capucinus).
Identical genetic profiles of the latter three isolates indicate the persistence of a
single M. tuberculosis strain in this population since at least 2006. Results of the
outbreak investigation in the captive vervet monkey colony indicate that it was
caused by two unrelated strains, while all 13 M. tuberculosis isolates from 11
animal species in the NZG showed different VNTR patterns. A substantial
increase in tuberculosis cases of 60% was recorded in the NZG, compared with
the previous reporting period 1991–2001, and may indicate a countrywide trend
of increasing spillover of human tuberculosis to wild animals. South Africa ranks
among the countries with the highest-tuberculosis burden worldwide, complicated
by an increasing rate of multidrug-resistant strains. Exposure and infection
of captive wildlife in this high prevalence setting is therefore a growing concern
for wildlife conservation but also for human health through potential spillback.
