Biology Reference
In-Depth Information
model to study human tuberculosis infection (Lin
et al
.,
2009
). Additionally,
this research on
M. fascicularis
points to an interesting phenomenon which is
that it appears that at least some primate taxa are more susceptible to TB than
are others. Further, even within a primate genus, response to infection with
M. tuberculosis
has been shown to differ greatly among congeneric species
with some (e.g.,
M. fasicularis
) able to sustain chronic, slowly progressive
disease similar to that which occurs in humans, while others (e.g.,
M. mulatta
)
succumb rapidly to the disease (Walsh
et al
.,
1996
). These differences in
response to exposure are important, because animals which quickly succumb
to the disease are unlikely to be reservoirs, while those with sufficient resist-
ance to contain the infection at a subclinical level may be able to harbor and
transmit the mycobacteria to conspecifics and humans.
Of course, given the widespread use of long-tailed macaques in laboratory
settings, the issue of TB infection in this setting is important in and of itself par-
ticularly because epizootics in the laboratory can lead to widespread culling of
animals and disruption of experimental protocols. In response, since the 1970s,
surveillance programs have been instituted to more actively detect and respond
to the presence of TB in laboratory primate populations(Roberts and Andrews,
2008
). Unfortunately, diagnosis of TB in macaques, as in humans, is bedeviled
by the lack of sensitive and specific laboratory tests capable of differentiating
exposure from latent and active infection. The intradermal tuberculin skin test
(TST) is the test that over the past decades has commonly been employed in
laboratory settings. However, recently newer serologic and molecular tests,
alone and in combination, show promise as improvements on these traditional
approaches (Lerche
et al
.,
2008
).
The impact of TB in free-ranging long-tailed populations, especially popu-
lations that have frequent and intense contact with human populations where
TB is endemic is not well understood. Much of the natural range of
M fascicu-
laris
coincides with hyperendemic areas for TB. Indeed, some of our unpub-
lished data support the logical expectation that synanthropic populations of
M fascicularis
would show evidence of exposure to TB. Yet to be explored is
research investigating the incidence and/or prevalence of TB exposure in more
remote populations with less contact with humans. One of the many questions
that remain is how exposure to TB impacts the health of these populations.
This is a particularly difficult question to explore because current methods for
detection of exposure to TB require that the animal be sedated, a tuberculin
skin test be placed and follow-up at 24, 48and 72 hours. Such an approach is
rarely feasible in free-ranging populations. Our research team is working on
developing techniques that allow for the noninvasive monitoring of TB expos-
ure in primate populations.
