MEDICAL PARASITOLOGY

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MEDICAL PARASITOLOGY ENTOMOLOGY

• LECTURER
• SR. NORAZSIDA RAMLI

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Intestinal Sporozoa

• Cryptosporidium parvum
• Isospora belli
• Cyclospora cayetanensis
• Sarcocytis species

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General characteristics

• 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.

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Cryptosporidium parvum

• 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.

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Life cycle
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Transmission

• 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

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Pathogenesis

• 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.

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Laboratory diagnosis

• Biopsy
• Microscopic examination
• Modified acid fast stain
• Sheathers sugar flotation method
• Formalin fixed
• Giemsa stained smears
• Immunodiagnostic assay
• Enzyme linked immunosorbent assay (ELISA)
• Fluorescent antibody detection methods

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Treatment

• Highly active antiretroviral treatment (HAART) of
  HIV for AIDS patient.
• Nitazoxanide- non-immunocompromised individuals.

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Prevention

• 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.

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Isospora belli

• 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.

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Life cycle
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Transmission

• Occurs by ingestion of water or food containing
  infective oocysts.
• Zoonotic transmission does not occur.
• Unprotected sexual activities anal-oral
  sexual.

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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

• Similar to C. parvum.

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Treatment

• Asymptomatic individuals may not require
  treatment
• Trimethoprim-sulfamethoxazole
• Metronidazole
• Tetracycline
• Pyrimethamine-sulfadiazine

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Prevention

• Good personal hygiene
• Good sanitary conditions
• Protected homosexual contact

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Cyclospora cayetanenis

• Oocyst spherical similar like C. parvum but
  larger than 8-10µm, contains 2 sporocysts, each
  containing 2 sporozoites.

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Life cycle
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Transmission

• Occurs by ingestion of contaminated food or water.

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Pathogenesis

• Incubation period 2 to 7 days
• Clinical manifestation
• Diarrhea
• Myalgia
• Anorexia
• Weight loss
• Fatigue
• Vomiting
• flu-like symptoms

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Laboratory diagnosis

• Flotation
• Microscopy examination using phase contrast
  microscopy and electron microscope.

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Treatment

• Trimethoprim-sulfamethoxazole

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Prevention

• Good hygiene
• Good sanitation practices
• Adequate water treatment methods
• Thorough washing of fruits and vegetables

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Sarcocytis species

• S. bovihominis- in cattle
• S. suihominis- in pigs
• Oocyst oval, contains 2 sporocysts with 4
  cigar-shaped 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.

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Life cycle
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Transmisson

• 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).

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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

• Microscopy examination
• Muscle biopsies ? histological method

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Treatment

• No treatment for the muscle form of sarcocytis
  infection.
• Trimethoprim sulfamethoxazole
• Pyrimethamine - sulfadiazine

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Prevention

• Adequate cooking of meat
• Avoidance of contact with animal feces
• - Prevents infection of humans as intermediate
  hosts.