3. General characteristics
Largest protozoan parasite of man
Only the ciliated parasite infecting human
Organ for locomotion is cilia
Cilia are present in both trophozoite and encysted
stage
Highly organized protozoa
Multiply asexually by transverse binary fission
Multiply sexually by conjugation
Compact nucleus; macronucleus and
micronucleus
4. General characteristics
Macronucleus divides amitoically
Micronucleus divides mitotically and has
reproductive function
It follows commensalism
Causes balantidiasis or balantidiosis(cilliary
dysentry)
It is an intestinal parasite of human and non-
human primates
Pig- natural host
Human- rare and incidental host
5. History
Malmsten reported the first case at Stockholm
in 1857
He was first to discovered it and named as
Paramacium coli
It was renamed as Balantidium coli by Stein in
1863
Morphologically different specimens gathered
from different host species, in 1992 by
McDonard and in1934 by Hagner
6. History
Different morphological species have different
nutritional requirement in vitro culture,
Barbosa et al., 2015; Levine, 1940
Levine in 1961 considered all these species to
be synonyms of Balantidium coli
Genetic analysis from different species
In 2011, Ponce-Gordo et al., concluded only
one specie infects warm blooded animals,
Balantidium coli
7. Geographical distribution
Cosmopolitan in distribution
Mainly found in pig raising areas
More common in temperate and tropical
regions
The Philippines, Papua New Guinea, some
Pacific Islands, some regions of Central and
South America and central Asia are considered
endemic areas
9. Epidemiology
The overall prevalence is estimated to be 0.02
to 1%
The number may be more as disease is
asymptomatic
In endemic areas,
o In South America the prevalence rate was 1 to
12% in late nineties
o Nearly, 30% cases in Oceania in 2013
o West Irian district of Indonesia, prevalence
rates has been reported upto 20%
10. Epidemiology
o It frequency of occurrance is less reported
from Indin
o In some pig-raising areas of New Guinea,
human infection rates are as high as 28%
An outbreak of balantidiasis on the Pacific
island of Truk in 1971 led to 110 human
infections
Infection tends to be more common among
humans who handles pigs
11. Habitat
Lives in lumen of large intestine of human,
pigs, rats and other mammals
Reservoir
Swine(pigs) are reservoir host
Source
Contaminated food and water with cysts
Infected hands with faeces
12. Morphology
Organism has two stages; trophozoite and cyst
A. Trophozoite
It measures from 30µm to 300 µm in length
and its breadth varies from 30µm to 100 µm
Oval in shape, greenish gray in colour
Sac like structure, Balantidium means little
bag
Body surface covered with cilia
Actively motile
13. Morphology
It has pointed/conical anterior end and rounded
posterior end
At one side of anterior end, located a
conspicuous V- shaped cytostome
Cytostome leads to funnel-shaped cytopharynx
No intestine
Posterior end contains a minute cytopyge
Contains two contractile vacuoles in cytoplasm
Many food vacuoles
14. Morphology
Two nuclei: Macronucleus:
I. A large kidney shaped
II. Situated in the middle of the body
Micronucleus:
I. Lies in the concavity of macronucleus
Invasive form
Found in lumen of large intestine
Found in dysenteric stool
It can ingest Rbc, fat droplets and bacteria
15. Morphology
A. Cyst:
Round and smaller than trophozoit
Contains single cell inside cyst
Measures 40µm to 60µm in diameter
Yellowish or greenish with hyaline cytoplasm
Cyst wall has two membrane
A thick-transparent double-layered wall
surrounds the cyst
It has granular cytoplasm
Contains both micro and macro nucleus and
refractile body
16. Morphology
Younger cyst may have cilia but mature cysts
do not
Cilia retracted inside cyst wall
Sometimes contractile vacuole may remains
active during encystment
Encystment in host, under condition like
constipation and bowel dehydration
Encystment may undergo outside of host
body
Non- replicating encysted stage, develops in
lower colon
17. Morphology
Excreted in feces
This stage is responsible for transmission of
Balantidiasis
It is resistive form and infective stage
Found in chronic case and carriers
In stained, macronucleus and some vacuoles
are easily seen
Cilia can be seen
22. Life-cycle
Balantidium coli passes its life cycle in two
stages, but in single host
Pig- The natural host
Man- Rare and incidental host
Cyst-The infective stage of the parasite
Portal of entry-Mouth, by ingestion
Once the cyst is ingested via feces-
contaminated food or water
It passes through the host digestive system
23. Life-cycle
The tough cyst wall resist degradation in the
acidic environment of the stomach
It also resist basic environment of the small
intestine until it reaches the large intestine
Excystation takes place
Excystation produces a trophozoite from the
cyst stage.
Single cyst give rise single trophozoite
Trophozoite may remain in lumen or enter sub-
mucosa of large intestine
24. Life-cycle
Grows and multiplies asexually by transverse
binary fission
Each division produces two daughter
trophozoite
Binary fission occurs by division of
micronucleus followed by division of
macronucleus and the cytoplasm
Successive division produces a large number
of trophozoite
25. Life-cycle
Sexually divides by conjugation
Conjugation takes place when two trophozoite
enclosed in a cyst
An exchange of nuclear material and individual
separates
After certain period, trophozoite encyst into cyst
in lower part of intestine
Excreted in feces
Trophozoite in feces do not encyst and
disintegrate in the environment
But cyst are infective to man
When man ingest cyst , life cycle repeats again
27. Transmission
Transmitted by fecal-oral route, with cyst and
less probably with trophozoite
Contaminated water and food is the main
source of transmission
Transmission by coprophagia could occur in
animals
28. Pathogenesis
Found both as a trophozoite and a cyst
Found in lumen of large intestine but invasion
of intestinal mucosa is its key feature of
pathology
Invasion is mediated by
I. Mechanical action by ciliary movement of
the trophozoite
II. Production of hyaluronidase by parasite
Invades mucosa and sub-mucosa causing
ulcers
29. Pathogenesis
Ulcers:
I. Ulcers are similar to that of intestinal
amoebiasis
II. Found in caecum, ascending colon, sigmoid
colon and rectum
III. Oval or round in shape
IV. Are multiple in numbers having undermined
edges
V. Floor of ulcers contains pus and necrotic
materials
30. Pathogenesis
VI. Trophozoites do found in pus and at the
edges of ulcers
VII. Ulcers invades polymorphonuclear cells,
eosinophils and lymphocytes
VII. Ulcers do not invade muscular layer like
that of amoebic ulcers
VIII. Presence of trophozoite confirms the
Balantidium ulcers and diagnosis proceed
IX. Major complication is perforation
X. Liver , lung and brain abscesses are not found
32. Clinical manifestation
Generally, it is a self-limiting and asymptomatic
infection
Causes Balantidiasis or ciliate dysentery
A. Diarrhoea alternating with constipation is typical
symptoms in mild infection
B. Stool contains blood and mucus in acute
infection
Symptoms are similar to amoebic dysentery
headache, fever, nausea, vomiting, severe
abdominal pain and intestinal colic
Liver , lung and brain abscesses are not found
33. Clinical manifestation
Ulceration of gut wall
Perforation of intestine
Haemorrhage, shock and even death may
occur
C. In chronic cases, diarrhoea alternating with
constipation occurs
Diarrhoeal stool contains rare trace of blood
and lots of mucus
Presence of parasite in stool is less common
35. Laboratory Diagnosis
Microscopic examination of stool
Trophozoites can be easily detected in saline
smears by their size and their slow motion
Morphology of the macronucleus can be
easily recognized in both trophozoites and
cysts in temporary smears stained with iodine
Other staining methods such as hematoxylin-
eosin or trichrome are also useful
Concentration method by centrifugation
37. Treatment
Tetracycline is drugs of choice,500mg for 10
days, four times daily
Metronidazole,750 mg, 3 times daily for 5
days
Iodoquinol, 650mg, 3 times daily for 20 days
Metronidazole and Iodoquinol are alternative
drugs
39. Prophylaxis
Sanitary disposal of human and pig feces
Eradication of contaminated food and water
either from pig or human
boiling kills cyst
Resistant to low dose of chlorine
Stool examination of food handlers of endemic
area
Avoid eating uncooked vegetables and fruits
that cannot be peeled off of sewage disposal
area
40. Notes
There are no data on prepatent and incubation
periods of B. coli in humans
In piglets and non-human primates, the
incubation period ranges from 3 to 6 days
The infectious dose or dose-response for
trophozoites or cysts is not known.
The disease is communicable (infectious) for as
long as organisms are excreted
Cyst can survive for several weeks and
trophozoite die at faster rate (hours) outside host