134 F.J. Salguero
Similar patterns have been observed in domestic
pigs with M. bovis infection. These patterns may
change in non-natural or artificial manage-
ments (Martin-Hernando et al., 2010) or after
infections with other mycobacteria as M. caprae
(García-Jiménez et al., 2013b). The histopatho-
logical features of the granulomas in swine are
similar to those observed in cattle and the differ-
entiation of granulomas by development stage
has also been used in this species (García-
Jiménez et al., 2013a, 2013b). Occasionally,
wild boar show small lesions heavily mineralized
with a very thick rim of fibrous capsule and with
poor cell component in lymph nodes, normally
associated to high health status in the group.
Using IHC techniques to determine the
presence of different cell populations and cyto-
kine expression within granulomas, it has been
shown that wild boar show large numbers of
macrophages in early stage granulomas and
T-cell distribution similar to lesions in cattle.
There is a high expression of iNOS in stage
I, II and III granulomas and to a lesser extent in
a rim surrounding the necrotic cores in stage IV
granulomas, as an attempt from the animal to
control the mycobacterial infection and spread
(García-Jiménez et al., 2013a). These features
are different from what is observed in fallow deer
granulomas (García-Jiménez et al., 2012).
Typical responses in wild boar include very
active phagocytosis and bacterial lysis sustained
by macrophages and iNOS in initial stages
(García- Jiménez et al., 2013a). The involvement
of B cells is not significant as observed in cattle,
and the typical nests of B cells have not been
found (García-Jiménez et al., 2013a).African buffalo and lechweAfrican buffalo (Syncerus caffer) and lechwe
antelope (Kobus leche) have both been found to
be important wildlife reservoirs of bovine tuber-
culosis in South Africa and Zambia, respectively
(Fitzgerald and Kaneene, 2012). Macroscopic
lesions in buffalo are mostly restricted to retro-
pharyngeal, bronchial and mediastinal lymph
nodes, and interestingly few animals show gross
visible lesions in the lung (Laisse et al., 2011).
Gross lesions are typically single or multiple
granulomas with a caseous core and mineraliza-
tion. Microscopically, the lymph nodes show a
variety of inflammatory cells including epitheli-
oid macrophages, lymphocytes and MNGCs,
with a variable degree of necrosis, fibrous encap-
sulation and mineralization (Laisse et al., 2011).
The number of AFBs within the lesions is very
low, and the lesions in general are similar to
those observed in cattle or North American cer-
vids (Laisse et al., 2011).
In the lechwe antelopes, the typical site of
infection is the lung, followed by thoracic lymph
nodes (Gallagher and Macadam, 1972). The
lung lesions are typical of central necrosis and
light mineralization with the presence of abun-
dant AFBs. The lymph nodes show concentric
areas of mineralization (Gallagher and Mac-
adam, 1972).Brushtail possumThe possum serves as the principal reservoir of
tuberculosis in New Zealand (Fitzgerald and
Kaneene, 2012). Possums are highly susceptible
to M. bovis infection and the disease is fatal
within months (Ryan et al., 2006). The dissemi-
nated form of tuberculosis in this species results
in axillary and inguinal lymph nodes, which can
fistulize, draining infective AFBs through the
skin posing an important implication in the epi-
demiology of the disease (Cooke et al., 1995).Fig. 9.16. Solid well-encapsulated lesion in the
mandibular lymph node from a wild boar infected
with M. bovis. The lesion is also heavily mineral-
ized and ‘gritty’ on sectioning. Courtesy of ‘Red
de Recursos Faunisticos’ group, University of
Extremadura, Spain.