Biomedical Engineering Reference
In-Depth Information
parasitic relationship is usually not harmful, prevalence is
high, and reinfestation is probable. Complete eradication of
pinworms from a primate research facility is not a reason-
able goal, but levels of infestation can be reduced by
appropriate vermifuge treatment of animals and frequent
cage washing.
malignant tertian form is caused by Plasmodium falciparum,
and quartan disease is caused by P. vivax, P. malariae, P.
ovale, P. brazilianum, and P. knowlesi. Both the quartan and
tertian forms occur in nonhuman primates, and malaria has
been shown to be a true zoonosis, both in nature and in the
laboratory (
Collins et al., 1973; Whitney, 1976; Kalra, 1980;
Bennett and Warren, 1985
). P. cynomolgi infection of M.
fascicularis and P. brasilianum infection of New World
monkeys have been transmitted to man by mosquitoes. P.
knowlesi infection of monkeys has been found as a natural
infection in man (
Baird, 2009
), as have malarial parasites of
African monkeys. Accidental laboratory infections as well
as human volunteer studies have proven that P. cynomolgi
can be transmitted from nonhuman primates to humans via
infected mosquitoes (
Centers for Disease Control/National
Institutes of Health, 2009
).
Oesophagostomum
More than half of newly imported Old World primates
shed the hookworm-like eggs of the “nodular worm,”
Oesophagostomum apiostomum, which also resembles
hookworms in the adult phase. Transmission is fecal-oral
by ingestion of infective larvae, which hatch in the feces
within 48 hours. After ingestion, these pass directly into
the mucosa of the colon and induce the rapid development
of large, firm, often black, encapsulated nodules. These
nodules rupture in 5
e
8 days, and the worms escape into
the lumen of the intestine and mature. In animals
immunized by previous exposure, the worms may remain
in the nodules which persist and become caseous or
calcified. Heavy infection may cause diarrhea, adhesions,
or even death. Aberrant lesions occasionally found in
human liver and kidney are called “helminthomas”
(
Whitney, 1976
).
Prevention
Biosafety Level 2 conditions with special
emphasis on insect control are recommended. Universal
precautions should be observed when handling animals that
may have infectious particles in their blood.
Toxoplasmosis
Toxoplasmosis caused by Toxoplasma gondii is widespread
in humans and lower animals (
Fox et al., 1984
), but
reported cases of natural infection of nonhuman primates
are few (
Epiphanio et al., 2000
). However, baboons (Papio
spp.), chimpanzees, and M. arctoides have been experi-
mentally infected, and laboratory-associated infections
have been reported (
Centers for Disease Control/National
Institutes of Health, 2009
).
Prevention
Biosafety Level 2 with enteric precautions is
recommended.
Other Roundworms
Ascaris spp. are not likely to spread to people or among
animals held under sanitary laboratory conditions because
the ova require 4
e
5 weeks after passage in feces to reach
the infective stage. However, the zoonotic capability of
Trichuris trichuria, the human whipworm, has been
demonstrated by experimental transmission of ova from
monkeys to man (
Horii and Usui, 1985
). Therefore, these
and other roundworms, including the hookworms (Necator
americanus and Ancylostoma duodenale), Terniden
diminuta, and Trichostrongylus spp., should all be regarded
as zoonoses (Fox et al., 1984).
Prevention
In the general human population, trans-
mission of Toxoplasma is transplacental, by ingestion of
undercooked meat, or by exposure to oocysts. Oocysts
are common in soil contaminated by cat feces. In the
laboratory setting, fecal contamination would be the
potential route of transmission, thus Biosafety Level 2 is
recommended.
Trypanosomiasis
The diseases caused by protozoa of the genus Trypanosoma
are characterized by fever, lymphadenopathy, localized
edema, and frequent progression to meningoencephalitis
with convulsions and death. Chagas disease, caused by the
hemoflagellate Trypanosoma cruzi and transmitted to
humans by blood-sucking triatomid bugs, exists only in the
Americas, where it is estimated that the overall prevalence
reaches 16 million cases (
World Health Organization,
1990c
). The Trypanosoma spp. that cause African sleeping
sickness are carried by the tsetse fly, a member of the
Chrysops genus that includes deer flies.
Protozoa
The protozoa are unicellular organisms, many of which are
important parasites of human and nonhuman primates.
These include agents that cause systemic, respiratory, and
gastrointestinal disease.
Malaria
Malaria is the most important protozoan disease. The global
incidence of malaria is considered to be approximately 110
million clinical cases annually with 270 million people
being infected (
World Health Organization, 1990a
). The
