Balantidium coli is the largest protozoan parasite that inhabits the large intestines of humans and other primates like pigs and monkeys. It exists in two stages - the trophozoite, which is the invasive stage, and the cyst, which is the infective transmission stage. Balantidium coli is found worldwide and can be transmitted through ingestion of contaminated food, water, or undercooked meat containing the cysts. In the intestines, the cysts excyst into trophozoites that colonize and cause damage to the large intestine mucosa through enzyme production, potentially resulting in ulcers, diarrhea, dysentery, and other gastrointestinal symptoms. Diagnosis involves stool examination and treatment focuses on hy

1. Balantidium coli

2. Balantidium coli
Largest protozoal parasite inhabiting large
intestine of man. Also found in pigs and
monkeys.
It is found world wide

3. Morphology :- the parasite is observed in two stages only which are
:-
A – trophozoite :-
• Large size (40 µm to more than 70 µm) .
• Invasive stage .
• Ovoidal in shape .
• Covered by cilia & the anterior end are longer than the
posterior end .
• Anterior end there is mouth called cytosome
• Have two nuclei , the macronucleus (the largest
one) & micronucleus (the smallest one ) .
•The macronucleus is kidney or bean in shape .
• The micronucleus is small spherical shape
located in the concavity of macronucleus .
• Have two secretory contractile vacuoles .
• Numerous food vacuoles .

4. B- Cyst :-
•Oval
•Thick outer wall
•Contain the macronucleus and contractile vacuoles are
visible in the cyst .
•The cilia are undetectable , only the roots may present .

5. Multiplication :- occur by two method
1- Asexual type by binary fission .
2- Sexual type by conjugation .
Life cycle :-
•No intermediate host is required .
•Mature cysts are passed with feces.
•Transmission :- by ingestion of contaminated food or
water (NOT in undercooked meat) with feces contain
the mature cyst .
•Excystation occurs in the small intestine, and the
trophozoites colonize in the large intestine.
•Trophozoites undergo encystation to produce infective
cysts.
Cysts are the infective stage of this parasite.

7. Pathogenesis
• Parasite produces hyaluronidase enzyme and
may cause mucosal damage.
• Which results in small superficial ulcer
which may penetrate upto submucosa.
• Diarrhea and dysentery can be developed
• Abdominal colic, nausea and vomiting may
occur.

8. • Laboratory diagnosis
• Stool examination
• Prophylaxis
• Personal hygiene
• food and water hygiene