Isospora belli, formerly known as Cystoisospora belli, is a gastrointestinal protozoan parasite. It is found worldwide but especially in tropical and subtropical regions. While most infections are asymptomatic, it can cause diarrhea and weight loss in immunocompromised individuals like those with AIDS. The life cycle involves both asexual and sexual reproduction within intestinal epithelial cells. Diagnosis is made by identifying oocysts in the feces which contain sporocysts and sporozoites. Treatment involves antibiotics like trimethoprim-sulfamethoxazole which can clear symptoms within a few days.

1. Isospora belli
( Cystoisospora belli )
Student Name and ID number
Waad Aldosary, 442203625
Amani Alsharidah, 441203711
Applied Entomology and Parasitology
Zoo 611

2. Outlines
2.Geographic
Distrbtion
4.Morphology
1.Introduction 3.Ebidermiology 5.Symtomps
6.Diagnosis
7.Pathway
8.Treatment

3. 1- Introduction
•Cystoisospora belli (formerly known as Isospora belli) is
a gastrointestinal protozoan in the Phylum
Apicomplexa.
•This group of parasites are referred to as coccidia.
Oocytes of Isospora belli showing
Asporulated oocytes containing two sporocytes, each
of which contains 4 sporozoites (left)
And acryospora-like oocytes containing sparozoites
enclosed in a single sporocyst (right)

4. 1- Introduction
•The Apicomplexa constitute a large protozoan
phylum of obligate eukaryotic intracellular
parasites responsible for many serious
diseases of humans, domestic animals and,
making these parasites economically important
for medical research.

5. 1- Introduction
•In patients with AIDS and other
immunodeficiencies, it is an
opportunistic pathogen that can
cause watery diarrhea and
weight loss.

6. Isospora belli
ISOS - Greek
Identical Sporos
Cysts
Latin – Bellum
Belli

7. 2- Geographic distribution
Geographical distribution of
Cystoisosporiasis is Worldwide,
especially in
tropical and subtropical areas.
Such as Haiti, Mexico, Brazil and
southeast Asia.

8. 3- Epidemiology
•Several hundred million humans
become infected; the symptoms
are called traveller’s disease.

9. 3- Epidemiology
•Immunocompetent patients with
Isosporiasis, infants and young children
seem to have more severe manifestations
than in adults.
• Chronic diarrheal symptoms by I. belli
infections have been reported in adults
without concurrent immunosuppression.
•The gastrointestinal symptoms of patients
with isosporiasis usually subside within a
few days after initiation of treatment.

10. 3- Epidemiology
It is note that infection with I. belli usually
produces more aggressive and
prolonged period of symptoms in
patients with acquired immunodeficiency
syndrome (AIDS) than in
immunocompetent individuals.
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11. 4- Morphology
Coccidian species belongs to the phylum
Apicomplexa (Sporozoa) and is characterized by a life
cycle comprising of:
1. Asexual generations (schizogony, sporogony) and
2. Sexual phase (gamogony).

12. 4- Morphology
• The sexual phase runs inside
vacuoles of epithelial cells of
the human small intestine.
• All developments occur inside
the host cell within a so-called
parasitophorous vacuole.

13. 4- Morphology
• The oocyst is formed after the fusion of a
motile male gamete (microgamete) with a
large, nonmotile female (macrogamete).
• The zygote develops a double-layered wall
and thus becomes oocyst, which measures
25–35 x 18–20 μm in size.

14. 4- Morphology
•Inside these oocysts two sporocysts containing each
four sporozoites are developed within about 3 days after
the oocysts had been excreted within feces.
•In contrast to the oocysts of other species, those of
Isospora belli are long ovoid.

15. •In the case of sufficient
humidity, these oocysts remain
infectious for at least 1 year and
also survive temperatures close
to the freezing point.

16. Life cycle

17. 5- Symptoms of the coccidiosis
Infections and symptoms may occur 2 days after
infectious oocysts are ingested during the
ongoing phase of schizogony, leading to the
destruction of intestinal epithelial cells of the host.
1. Fluid diarrheas.
2. Vomiting.

18. 5- Symptoms of the
coccidiosis
•In the case of HIV patients,
symptoms may become life
threatening, the parasites were
not only found in the intestinal
epithelial cells but also in lymph
nodes far from the intestine.
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19. 6- Diagnosis
•The oocysts can be diagnosed in the feces.
• In fresh stools they are unsporulated.
• In Older stools they appear sporulated
containing two sporocyst each with four
sporozoites.
In cases of detected blood eosinophilia, feces
should be investigated, since the agents of
traveller’s disease may also induce this
symptom.

20. 7- Pathway of infection
Oral by ingestion of infections with oocysts
contaminated food or drinking water.
•Prophylaxis: Avoiding contact to human
feces or uncooked contaminated drinking
water.

21. Important terms
•Incubation period:
Period between infection day and the first
clinical symptoms.
•Prepatent period:
Period to reach maturity
•Patency:
The following period until the end of the
production of transmittable stages.

22. 7- Pathway of infection
•Incubation period:
2–13 days, which correspond with the asexual
phase in the intestine.
•Prepatent period:
•7–9 days.
•Patency:
2 weeks up to 1–2 years (in the case of HIV
patients).

23. 8- Treatment
•In the case of immunocompetent persons, the
disease runs mostly self-limiting .
•However, cases of weak (children), symptoms of
disease may become chronic.
•The gastrointestinal symptoms of patients with
isosporiasis usually subside within a few days after
initiation of treatment with combination of
trimethoprim and sulfamethoxazole.

24. Video

25. Thanks
ANY QUASTION?

26. Referances
https://www.omicsonline.org/singapore/cystoisosporiasis-peer-reviewed-pdf-ppt-articles/
https://www.uptodate.com/contents/epidemiology-clinical-manifestations-and-diagnosis-of-
cystoisospora-isospora-infections#H27632855
https://pdfs.semanticscholar.org/05a1/04e4fa4a8270a835616f10075a1b2eeb870c.pdf?_ga=2.228953116
.1202837638.1633165606-1618893723.1633165606
HUMAN PARASITOLOGY,FOURTH EDITION,BURTON J. BOGITSH,PHD CLINT E. CARTER,PHD, THOMAS N. OELTMANN,PHD