MEDICAL
PARASITOLOGY
&
ENTOMOLOGY
LECTURER:
SR. NORAZSIDA RAMLI
Intestinal Sporozoa
Cryptosporidium parvum
Isospora belli
Cyclospora cayetanensis
Sarcocytis species
General characteristics
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Nonmotile
Obligate intracellular parasites
Having complex life cycle
With alternating sexual and asexual phases
Oocyst containing mature sporozoites
Sporocyst- a sac within certain oocysts
containing sporozoites.
Cryptosporidium parvum
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Oocyst: - round to slightly oval, 4-6µm,
mature oocyst: - contains 4 sporozoites
surrounded by a thick double layered wall; no
sporocyst are visible; dark staining granul are
usually apoparent.
Schizont and gametocytes: small, 2-4µm, are
produced during the life cycle, but rarely seen in
human specimens.
Cause cryptosporidiosis, zoonotic transmission
does occur.
Life
cycle
Transmission
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Occurs by ingestion of food or water
contaminated with infective oocysts
Person to person contact
Distributed worldwide, in most untreated water
supplies
Difficult to remove physically
Resistant to many chemicals including chlorine.
Reservoir host: cattle
Pathogenesis
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Causes self-limited diarrhea in immunocompetent
individuals
Incubation period: one to several weeks.
Symptoms: nausea, fever, vomiting, anorexia, abdominal
cramps, watery diarrhea, constipation
Recovery- dependent on the immune status of the host.
Serious in infant- cause of morbidity and mortality
Immunocompromised individuals- often suffer severe,
intractable diarrhea.
Patient with AIDS- becomes progressively worse, does not
respond to treatmentmay cause death, respiratory tract
may also be infected.
Laboratory diagnosis
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Biopsy
Microscopic examination
Modified acid fast stain
Sheather’s sugar flotation method
Formalin fixed
Giemsa stained smears
Immunodiagnostic assay
Enzyme linked immunosorbent assay (ELISA)
Fluorescent antibody detection methods
Treatment
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Highly active antiretroviral treatment (HAART)
of HIV– for AIDS patient.
Nitazoxanide- non-immunocompromised
individuals.
Prevention
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Proper water treatment
Good sanitary practice
Treat water supplies with filtration technique, as
well as chemicals
Zoonotic transmission may be prevented by
reducing or eliminating contact especially of
immunocompromised individuals, with animals.
Isospora belli
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Oocyst: elliptical or oval, 25-30µm by 10-17µm
Immature oocyst: containing a single central
mass.
Mature oocyst: develops 2 sporoblasts, which
develop into 2 sporocysts, each containing 4
cigar-shaped sporozoites, surrounded by double
layered wall.
Life
cycle
Transmission
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Occurs by ingestion of water or food containing
infective oocysts.
Zoonotic transmission does not occur.
Unprotected sexual activities: – anal-oral sexual.
Pathogenesis
Infection is often asymptomatic and self-limited.
 When present, symptoms include:
-diarrhea
-abdominal pain
-Weight loss
-anorexia
 An increase of infection in AIDS patients has
been reported in recent year.
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Laboratory diagnosis
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Similar to C. parvum.
Treatment
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Asymptomatic individuals may not require
treatment
Trimethoprim-sulfamethoxazole
Metronidazole
Tetracycline
Pyrimethamine-sulfadiazine
Prevention
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Good personal hygiene
Good sanitary conditions
Protected homosexual contact
Cyclospora cayetanenis
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Oocyst: spherical –similar like C. parvum but
larger than – 8-10µm, contains 2 sporocysts,
each containing 2 sporozoites.
Life
cycle
Transmission
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Occurs by ingestion of contaminated food or
water.
Pathogenesis
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Incubation period: 2 to 7 days
Clinical manifestation:
Diarrhea
Myalgia
Anorexia
Weight loss
Fatigue
Vomiting
“flu-like” symptoms
Laboratory diagnosis
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Flotation
Microscopy examination – using phase contrast
microscopy and electron microscope.
Treatment
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Trimethoprim-sulfamethoxazole
Prevention
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Good hygiene
Good sanitation practices
Adequate water treatment methods
Thorough washing of fruits and vegetables
Sarcocytis species
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S. bovihominis- in cattle
S. suihominis- in pigs
Oocyst: oval, contains 2 sporocysts with 4 cigarshaped sporozoites, 25-33µm, sporocyst is
similar to C.parvum but larger, bout 9-16µm,
surrounded by double-layered wall
Sarcocystis “lindemanni” is the term gien to
those organisms that may potentially parasitize
humans.
Life
cycle
Transmisson
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Occur by ingestion of improperly cooked meat
(containing the sarcocyst form in muscle).
By ingestion of animal feces-contaminated food
or water ( oocyst stage in stool).
Pathogenesis
Symptoms:
-diarrhea
-abdominal pain
-weight loss
-muscle pain may be associated with the
presence of sarcocysts in human striated muscle
 Most cases r asymptomatic
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Laboratory diagnosis
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Microscopy examination
Muscle biopsies  histological method
Treatment
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No treatment for the muscle form of sarcocytis
infection.
Trimethoprim – sulfamethoxazole
Pyrimethamine - sulfadiazine
Prevention
Adequate cooking of meat
 Avoidance of contact with animal feces
- Prevents infection of humans as intermediate
hosts.
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