Largest and least common protozoan pathogen of humans. Causes life-threatening colitis.

1. BALANTIDIUM COLI
By, Leyon Selvin Raj,
Tutor,
BN Patel institute of paramedical & Science, (Paramedical Division).

2. Blantidium coli
• Largest and least common protozoan pathogen of
humans.
• Caused life threatening colitis.
• Avoidable by antibiotic therapy.
• Fatalities are due to diagnostic imprecision.

3. Epidemiology
• Most commonly reported in
• Tropical and sub tropical
• Particularly central and south America
• Iran, Papu New Guinea and Philippines

4. • Prevalence is less than 1%
• Found in many mammals other than humans
• Pigs and monkeys- especially
• Swine- imp. Animal reservoir
*The largest reported balantidiasis, involves 110
persons, resulted from gross contamination of ground
and surface water supplies by pig feces after a severe
typhoon.

5. Morphology
• B. coli occurs in two stages
• Trophozoite
• Cyst

6. Trophozoite
• Lives in large intestine.
• Feeding on cell debris, bacteria, starch grains, and
other particles.
• Motile – found in dysenteric stool.
• Large ovoid cell. 60-70µm in length and 40-50µm in
breath. (200µm-large one)

8. Trop. Morp.
• At the anterior end, there is
a groove (peristome)
• leading to the mouth
(cytostome), and a short
funnelshaped gullet
(cytopharynx).
• Posteriorly, there is a small
anal pore (cytopyge).
• The cilia around the mouth
are larger (adoral cilia).

9. Trop. Morp.
• The cell has 2 nuclei—a
large kidney-shaped
macronucleus
• and lying in its concavity
a small micro nucleus.
• The cytoplasm has 1 or 2
contractile vacuoles
• And several food
vacuoles.

10. Cyst Morp.
• spherical in shape and
measures 40–60 μm in
diameter.
• It is surrounded by a thick and
transparent double layered
wall.
• The cytoplasm is granular.
Macronucleus, micro nucleus,
and vacuoles are also present
in the cyst.
• The cyst is the infective
stage of B. coli.
• It is found in chronic cases
and carriers.

11. Life cycle
• B. coli passes its life cycle in one host only
(monoxenous).
• Natural host: Pig
• Accidental host: Man.
• Reservoirs: Pig, monkey, and rat.
• Infective form: Cyst.

12. Mode of transmission
• Balantidiasis is a zoonosis. Human beings acquire infection by ingestion of
food and water contaminated with feces containing the cysts of B. coli.

13. Mode of transmission
• Infection is acquired from pigs and other animal
reservoirs or from human carriers.
• Once the cyst is ingested, excystation occurs in
the small intestine.
• From each cyst, a single trophozoite is produced
which migrates to large intestine
• Liberated trophozoites multiply in the large
intestine by transverse binary fission. Sexual
union by conjugation also occurs infrequently,
during which reciprocal exchange of nuclear
material takes place between 2 trophozoites
enclosed within a single cyst wall.
• Encystation occurs as the trophozoite passes
down the colon or in the evacuated stool. In this
process, the cell rounds up and secretes a tough
cyst wall around it.
• The cysts remain viable in feces for a day or 2
and may contaminate food and water, thus it is
transmitted to other human or animals.

14. Pathogenesis
• In Healthy individual, B. coli lives as lumen commensal
and is asymptomatic.
• Clinical disease occurs only when the resistance of host
is lowered.
• Trophozoites burrow into the intestinal mucosa, set up
colonies, and initiate inflammatory reaction.
• Leads to mucosal ulcers and submucosal abcesses,
resembling lesions in amoebiasis.
• They don’t invade liver, like E. histolytica,

15. Clinical Features
• Most infections are asymptomatic.
• Symptomatic disease (balantidiasis) resembles
amoebiasis causing diarrhea or frank dysentery with
abdominal colic, tenesmus, nausea and vomiting.
• Balantidium ulcers may be secondarily infected by
bacteria.
• Occasionaly, intestinal perforation peritonitis and even
death may occur.

16. Laboratory Diagnosis
• Stool Examination
• Demonstration of trophozoites and cysts in feces.
• Trophozoites- diarrheic feces
• Large in size, macronucleus, and motile
• Cysts- formed stool
• Round shape and large macronucleus.

17. • Biopsy
• Scrapings from intestinal ulcers can be examined for presence
of tropozoites and cysts.

18. • Culture
• B. coli – Locke’s egg albumin medium or NIH polyxenic
mrdium
• *rarely needed

19. Treatment
• Tetracycline- 500mg 4times/day for 10 days
• Alternative
• Doxycycline

20. Prevention (prophylaxis)
• Avoidance- Contamination of food and water with
animal and human feces
• Prevention of human-pig contact
• Treatment of infected pigs

22. Reference
• Farrar, J., Hotez, P., Junghanss, T., Kang, G., Lalloo, D.
and White, N.J., 2013. Manson's Tropical Diseases E-
Book. Elsevier Health Sciences.
• Paniker, C.J., 2007. Textbook of medical
parasitology (No. Ed. 6). Jaypee Brothers Medical
Publishers (P) Ltd.