Biomedical Engineering Reference
In-Depth Information
Where published values exist, there is often a wide range of
normals and frequently a limited number of species rep-
resented. Whenever possible, one should try to work with
the clinical pathology laboratory to establish colony
normals for the species and particular cohort of animals in
the facility.
The serum bank is another important element of base-
line data (
Morton et al., 2008; Sasseville and Diters, 2008;
Simmons, 2008
). Serum should be collected and frozen on
a regular basis (e.g. annually) for future use. These samples
may prove valuable for retrospective epidemiological
studies, as a resource for investigators, and to resolve an
institutional liability situation. Detailed and accurate
records must be available to make full use of the serum
bank. Along with the identification and health status of the
animal, one should be able to track the location of the
animal and what other animals it was exposed to at the time
of collection.
FIGURE 12.1
A grade 1 TST reaction. Bruising of the left eyelid
caused by injection of tuberculin is shown. A grade 1 TST is considered
negative.
Tuberculosis Screening
Tuberculosis is a highly contagious, fatal disease in NHPs.
The disease in NHPs is usually caused by Mycobacterium
tuberculosis and less commonly by M. bovis. Despite
a reduced overall prevalence, outbreaks of TB still occur,
disrupting research and endangering colony health. Accu-
rate TB diagnosis is imperative in the maintenance of
colony health.
Testing is performed biweekly in a quarantine situation.
In routine colony preventive health, frequency of testing
should be based on a risk assessment and ease of access to
animals. Quarterly testing is recommended but may not be
practical or prudent in every situation. Not only does
quarterly testing increase the chances of stopping an
unexpected outbreak early in its course, but it also allows
animals to be examined by the veterinary staff on a regular
basis. The most common method of testing is the intra-
dermal injection of mammalian old tuberculin (MOT) at
the edge of the upper palpebrum. This is analogous to the
TST in humans but the palpebrum is the preferred site of
testing because of the ease of observation without the need
for restraint. Instead of purified protein derivative that is
used in humans, MOT is used for the injection because it
has a higher concentration of TB antigens. A record should
be kept of which palpebrum is used and subsequent tests are
generally alternated between the two sides. The intradermal
injection may also be made in the skin of the abdomen,
though the sensitivity of this method may not be adequate
(
Capuano et al., 2003
).
The tuberculin test is read at 24, 48, and 72 hours by
observing the palpebrum for swelling and erythema. The
tests are graded one to five with one and two being negative,
three being questionable, and four and five being positive
(
Figures 12.1
FIGURE 12.2
A grade 2 TST. Various degrees of palpebral erythema
without swelling are shown. A grade 2 TST is considered negative.
FIGURE 12.3
A grade 3 TST. Various degrees of palpebral erythema
with minimal swelling or slight swelling without erythema are shown. This
reaction is considered questionable.
12.5
). For further information regarding
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