Like man, the nonhuman primate is susceptible to the wide variety of
bacterial agents. There is little difference in susceptibility between
most primate species; however, the macaques are more susceptible to
tuberculosis and enteric bacteria, whereas the New World primates are
more susceptible to the water-borne agents (Pseudomonas or Klebsiella).
The bacteria that deserve the most concern are Mycobacteriaciae,
Shigella/Salmonella, Campylobacter, and Klebsiella.
Mycobacteriaciae - Mycobacteria are responsible for tuberculosis, the
scourge of the primate owner and veterinarian. Tuberculosis has been
recognized as a common disease of captive primates for many years.
Early outbreaks were devastating, causing the loss of hundreds of
primates of many species. Species most susceptible are the macaques and
apes; the New World species seemingly are more resistant. Almost all
species can be experimentally infected. Historically, the three major
species of mycobacteria--avium, bovis, and tuberculosis--have been
incriminated as causing tuberculosis in the nonhuman primate. Recently,
many atypical mycobacteria have also been reported in the nonhuman
primate, including M. kansasii and M. scrofulaceum, all of which are
potential hazards to man. The extreme susceptibility of monkeys to
tuberculosis is often discussed; the disease is usually miliary, and
arrest and calcification are unusual. The danger to owners and others
who come in contact with infected monkeys is obvious. Control requires
an effective quarantine for newly arrived primates, isolation from
infected persons, and a rigorous testing program. It is generally
agreed that the route of initial infection is usually respiratory (60
per cent) or intestinal (40 per cent). Because of their fulminating
nature, terminal infections often present difficulty in establishing the
portal of entry because so many organs are involved in the generalized
infection.
The clinical signs of tuberculosis are not striking until the disease is
in an advanced stage. The first sign may be a slight behavioral
alteration. The animal may be slower than normal or stay along the
floor of the enclosure rather than climb the enclosure or cage wall.
Soon the infected animal will exhibit a dull appearance, crouch in the
corner, and refuse to eat. The latter may be all the owner notices;
coughing or other respiratory signs are conspicuously absent. Less
common signs that may or may not be present with tuberculosis include
diarrhea, skin ulceration, suppuration of Iymph nodes, and visible
enlargement of the spleen and liver. Often there are no clinical signs,
and the owner reports that the animal died suddenly without
explanation. Radiographs of the lungs, ect., are usually nondiagnostic
because of lack of calcification. The usual presence of mite
(Pheumonysis spp.) lesions in normal rhesus monkeys complicates the
radiographic diagnosis.
The lesions seen at necropsy are fairly typical yellowish-white to grey
nodules that range from pinpoint size to several millimeters in diameter
and appear just under the surface of the affected organs. As the
disease progresses, the nodules fill with caseous material and may
rupture and produce cavitation. Caseous, enlarged mediastinal lymph
nodes in the rhesus monkeys are almost pathognomonic for tuberculosis.
In baboons and apes, the disease is much more like that seen in man,
with caseation and eventual calcification. Cutaneous tuberculosis in
primates usually migrates to the regional Iymph nodes, and any draining
lymph node should be suspected as a tubercular lesion until proven
otherwise. Tuberculosis of the spine, or Pott's disease, also occurs in
monkeys and should be considered whenever there is unexplained paralysis of the hind limbs.
Tuberculin skin testing must be part of any physical examination of a
nonhuman primate. Newly imported primates should be tested biweekly and isolated until five negative tests have been certified. Approximately
15,000 tuberculin units (0.1 ml) of full-strength mammalian tuberculin
is given intradermally in alternating eyelids. The test is read at 24,
48, and 72 hours. A positive reaction is any erythema and/or edema that
persists for 48 hours or longer. Suspicious tests may be repeated at 7
days in the opposite eyelid or abdomen. Stabilized Old World primates
should be tested quarterly, and New World monkeys semi-annually.
Because of the public health danger and the potential resistance to
treatment, positive animals should be euthanatized; treatment is NOT
recommended. Atypical tuberculosis, other serologic methods, and so on, are beyond the scope of this article.
Shigella and Salmonella - Although shigellosis and salmonellosis are caused by two separate organisms, the symptons, signs, and treatment are
similar, so they will be discussed together. Shigella and salmonella
are frequently present in the alimentary tract of nonhuman primates.
Isolation of the organism from the carrier animal is difficult,
requiring numerous samples and enrichment techniques. A single negative
culture means nothing. Fortunately, the most serious human pathogens of
these two groups, Shigella dysenterriae type 1 and Salmonella typhi,
have only rarely been isolated from nonhuman primates; however, several
others (Shigella flexneri, S. sonnei, and Salmonella typhimirium, for
example), which are also infectious to man, have been recovered.
The literature contains many reports of infection in primates and few
reports of transmission to human beings. One of the earlier
transmissions reported was a case of shigellosis in a child who licked
an ice cream cone that had been touched by a monkey in a pet shop. This
illustrates the potential danger for infants and children in contact
with the species. Fortunately, the published reports of primate-to-man
infections are rare. The primate carrying the organism can have a
fulminating fatal infection at any time, with excretion of large numbers
of organisms during the course of the disease. This acute infection is
usually precipitated by some stress, such as environmental change of
corticosteroids.
Clinical signs of shigellosis and salmonellosis are weakness,
prostration edema of the face and neck, emaciation, and diarrhea with
mucas and/or blood. As a rule, a bloody dysentery eventually occurs in
shigellosis. Prolapse of the rectum is commonly seen, with death in a
few days to 2 weeks after the onset of signs. At necropsy, the large
intestine and diphtheritic colitis occurs with a varying degree of
exudation and necrosis of the mucous membrane and ulceration that may
penetrate the serosal surface.
Diagnosis is based on signs, necropsy, and culture results. Culture
must be fresh, byt, even so, the isolation rate is low. Treatment for
both entities is as follows: (1) take offor reduce feed; (2) provide
fluids--lactated Ringers, 1/2 strength with 2.5 per cent dextrose given
at a rate of 20 ml per kg or higher, depending on the state of
dehydration; (3) administer antibiotics--trimethoprim and sulfadiazine
(Tribrissen) will eliminate the carrier state if given conscientiously;
and (4) administer kaolin plus pectin (Pectolin).
The family medical practitioner should be made aware of any pet monkey
with symptoms of these diseases, particularly if children are or will be
contact with the primate.