Morphology, life cycle, epidemiology, symptoms, treatment, laboratory diagnosis, and prevention of the parasite, Isospora belli.

1. Isospora belli
Report by: Veronica Baje

2. Isospora belli
• Isospora belli is a protozoan parasite in the
Phylum Apicomplexa.
• This group of parasites are referred to as
coccidia.

3. Oocysts

4. Laboratory Diagnosis
• Fresh feces
• Duodenal contents

5. Life Cycle
• An oocyst with one sporoblast is released in stool of infected person
• After the oocyst has been released, the sporoblast matures further and divides into two
• After the sporoblasts divide they create a cyst wall and become sporocysts
• The sporocysts each divide twice, resulting in four sporozoites
• Transmission occurs when these mature oocysts are ingested
• The sporocysts excyst in the small intestine where sporozoites are released
• The sporozoites then invade epithelial cells and schizogony is initiated
• When the schizonts rupture, merozoites are released and continue to invade more
epithelial cells
• Trophozoites develop into schizonts, containing many merozoites
• After about one week, development of male and female gametocytes begin in the
merozoites
• Fertilization results in the development of oocysts, which are released in the stool.

6. Clinical Symptoms
• Asymptomatic – A number of infected
individuals remain asymptomatic.
• Isosporiasis – Infected patients may
complain of a number of symptoms:
• Mild gastrointestinal discomfort to
severe dysentery
• Weight loss
• Chronic diarrhea
• Abdominal pain
• Anorexia
• Weakness
• Malaise

7. Pathogenesis
• Marked villous atrophy
• Crypt hyperplasia in the small intestine

8. Epidemiology
• Africa
• Southeast Asia
• Central America
• Chile

9. Treatment
• Bland diet
• Plenty of rest
• Combination of trimethoprim
and sulfamethoxazole
• Perimethamine and
sulfadiazine

10. Prevention and Control
• Proper personal hygiene
• Adequate sanitation practices
• Protected sex