Biomedical Engineering Reference
In-Depth Information
The human agents have been experimentally trans-
mitted to several species of nonhuman primates (
Gibbs and
Gadjusek, 1976; Herzog et al., 2005
), but there are no
reported cases of human infection from working with them.
The chronic wasting disease prions of cervids, which pose
an unknown risk to humans following exposure, cause
progressive neurodegenerative disease in experimentally
infected squirrel monkeys (
Marsh et al., 2005
).
appeared in the early 1990s (
Centers for Disease Control,
1992a
). Transmission from man to monkey has been
reported (
Cappucci et al., 1972
), so the need for consci-
entious monitoring of people working with primate animals
remains essential to keep Mycobacterium from getting into
animal colonies.
Tuberculosis infections are acquired primarily from
aerosols via the respiratory route or the gastrointestinal
route. In addition to the possibility of exposure through these
common routes, laboratory workers have potential for
contact with the blood, sputum, excreta, cerebrospinal fluid,
exudates from lesions, and tissues of infected animals. Since
tuberculosis can be transmitted by blood, careless injection
procedures or failure to sterilize items such as tattoo needles
and thermometers between animals could result in the
spread of disease in a colony (
Whitney, 1976
). Tubercle
bacilli may even survive in heat-fixed smears (
Allen, 1981
)
and in inadequately formalin-fixed tissues.
Prevention
Biosafety Level 2 conditions and universal
precautions are recommended for working with prion-
infected nonhuman primates.
BACTERIAL DISEASES
Systemic Infections
Tuberculosis
Tuberculosis is the most important bacterial disease of
nonhuman primates because of its ubiquitous and insidious
nature and its ability to spread rapidly. Although it is
usually thought of as a respiratory disease, tuberculosis
may be found in any organ, so it should be regarded as
a systemic infection.
Most of the tuberculosis seen in nonhuman primates is
caused by the acid-fast bacillus Mycobacterium tubercu-
losis, but many different species have been recovered,
including M. bovis (
Renner and Bartholomew, 1974
), M.
avium (
Smith et al., 1973
), M. kansasii (
Valerio et al.,
1978
), M. scrofulaceum (
Renquist and Potkay, 1979
), and
M. intracellulare (
Centers for Disease Control, 1973
).
Tuberculosis occurs in all primate species, but suscep-
tibility varies. Young macaques are the most susceptible
and New World monkeys the least, but there have been
several outbreaks even in the latter. The human infectious
dose (ID
50
)ofM. tuberculosis is
Prevention
Prevention of exposure is of paramount
importance in controlling tuberculosis in primate facilities.
The quarantine of animals coming into a facility must be
long enough to detect any recently acquired infections that
have not yet produced a delayed hypersensitivity response
in the host. Even animals that are transported from one
stable colony to another could be exposed en route and
should be quarantined with tuberculin testing every 2
weeks for 90 days before being incorporated into the new
stable colony. Additional tests available include thoracic
radiographs, Primagam test, PCR testing of gastric
contents, or tracheal washes. A combination of tuberculin
skin testing and Primagam results proved to be the most
accurate means of detecting positive animals with the
lowest level of false positive results in a recent outbreak in
Chinese source rhesus monkeys (R. Bohm, personal
communication, 2006). Stable colony animals should be
tuberculin tested quarterly (
Henrickson, 1984
). Outbreaks
have been detected in imported animals as long as 8 months
after entry into quarantine. Care should be taken to separate
imported animals from existing colony animals even after
quarantine has ended or there is risk of spreading latent
tuberculosis infections to other studies. Similar precautions
should be taken for introduction of imported animals into
an existing breeding colony.
Tuberculin-negative animal contact personnel should be
Mantoux tuberculin skin tested routinely every 6 months
with 5 tuberculin units of purified protein derivative
(
Centers for Disease Control, 1990b
). Tuberculin-positive
people should be monitored medically whenever they have
respiratory symptoms that persist longer than those usually
seen with transient viral upper respiratory infections.
Human tuberculin converters should be referred to
a physician for follow-up with radiographs, cultures, or
other diagnostic procedures and treatment (
Chang et al.,
10 bacilli, and it is has
been postulated that as few as one bacillus can infect
a rhesus monkey. In young macaques, tuberculosis spreads
rapidly throughout a closed colony until all become
infected (
Keeling et al., 1969
). Older rhesus monkeys,
baboons, and apes usually have a slower form of the
disease, similar to that seen in people (
Whitney, 1976
).
Although documented cases are hard to substantiate,
naturally or experimentally infected nonhuman primates
have been suspected to be the source of some human
infections. During the 1970s the incidence of tuberculosis
in the USA dropped and routine tuberculin testing and
eradication of infected primate animals became common
practice in research facilities. However, in 1978 the
tuberculin conversion rate among personnel working with
infected animals was still reported to be more than 20 times
greater than that of the general population (
Kaufmann and
Anderson, 1978
). Tuberculosis in the USA began to
increase again in the 1980s, and multidrug-resistant strains
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