[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 7 Miscellaneous Protozoa
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stain periodic acid-Schiff (PAS). Giemsa-stained
biopsy material and fecal concentrate specimens
readily show the spores. It is important to
note that speciation of the Microsporidia
requires the use of transmission electron microscopy.
Molecular diagnostic methods are being
developed.
Life Cycle Notes
Transmission of Microsporidia may be direct or
may involve an intermediate host. On entering
the host, human infection is initiated when the
infective spores inject sporoplasm into a host
cell. A complex reproductive process occurs, new
spores emerge, and additional cells typically
become infected. Spores are dispersed into the
outside environment in the direct transmission
cycle in the feces or urine, or by the death of the
host. In addition, the spores may be ingested by
a carnivorous animal.
Epidemiology
Cases of E. bieneusi infection have been reported
in AIDS patients from Haiti, Zambia, Uganda,
the United Kingdom, the United States, and
the Netherlands. Although most documented
infections of Microsporidia parasites have
occurred in AIDS patients, cases in persons
with normal immune systems have also been
described.
Clinical Symptoms
Microsporidial Infection. Patients suffering
from infections with Microsporidia have been
known to develop enteritis, keratoconjunctivitis,
and myositis. Infections involving peritonitis and
hepatitis have rarely occurred.
Treatment
Albendazole is recommended for the treatment
of E. bieneusi; oral fumagillin is recommended
as an alternative treatment. Albendazole plus
fumagillin eye drops are recommended for the
treatment of Nosema infection.
Notes of Interest and New Trends
Persons infected with C. cayetanensis in addition
to Microsporidia have been reported and are
considered somewhat common.
In recent years, the United States Environmental
Protection Agency (EPA) has listed Microsporidia
in the EPA Candidate Contaminate List,
deeming it an emerging water-borne pathogen
needing monitorial attention.
Although Microsporidia infection in humans
mostly occurs in immunocompromised patients,
the further spread of AIDS worldwide increases
our need to understand and manage Microsporidia
for the near future.
Quick Quiz! 7-20
How do Microsporidia spores differ from other protozoan
spores? (Objective 7-11)
A. Double outer wall
B. Extruding polar filaments
C. Cilia
D. Pseudopods
Quick Quiz! 7-21
Of the following, which laboratory technique is
required for species identification of Microsporidia?
(Objective 7-8)
A. Giemsa-stained biopsy material
B. Electron microscopy
C. Fecal concentration
D. PAS stain
Quick Quiz! 7-22
The life cycle of Microsporidia is a complex process in
which both the infective and diagnostic stages are
spores. (Objective 7-5)
A. True
B. False
Toxoplasma gondii
(tock”so-plaz’muh/gon’dee-eye)
Common associated disease and condition
names: Toxoplasmosis, congenital toxoplasmosis,
cerebral toxoplasmosis.