This document summarizes information about Balantidium coli, the largest protozoan parasite that infects humans. It is classified within the kingdom Protista, phylum Ciliophora. B. coli has two life stages, a trophozoite stage that is motile and pear-shaped, containing two nuclei and contractile vacuoles, and a cyst stage that forms under conditions like constipation. B. coli typically infects pigs and is transmitted to humans via ingestion of cysts. In humans, it can cause diarrhea and dysentery through ulceration in the large intestine. Diagnosis involves finding cysts in feces and treatment involves antibiotics like tetracycline or metronidazole.

1. Balantidium coli
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2. CLASSIFICATION
 Kingdom : Protista
 Sub-Kingdom : Protozoa
 Phylum : Ciliophora (presence of
cilia)
 Class : Kinetofragminophorea
 Order : Trichostomatida
 Family : Balantidiidae
 Genus : Balantidium
 Species : coli

3. CHARACTERS
 “Largest protozoan parasite of man”
 Possess cilia – organ for locomotion
 Highly organized protozoa
 Compact nucleus – macronucleus and
micronucleus
 Macronucleus – horse shoe shaped; vegetative
functions, divides amitotically
 Micronucleus – small;
reproductive functions,
divides mitotically
 Follows commensalism

4. MORPHOLOGY
 2 stages - Trophozoite & Cyst
 Trophozoites – ovoid, egg – shaped, pear – shaped;
occasionally subcylindrical
 Body surface – covered with cilia
 Cytostome – permanent mouth
 Cytopyge - excretory organelle
 Trophozoite – 2 nuclei
 Occasionally, vegetative forms are seen without
macronucleus
 2 contractile vacuoles – one terminal; other near centre
 Food vacuoles – many; containing starch grains, cell
fragments, bacteria, erythrocytes
 Organism – actively motile and moves quickly when
examined under microscope

5. Contd..
 Under conditions like constipation & bowel
dehydration – organisms undergo encystment
inside the host
 May also undergo encystment outside
 Cysts are ovoid to spherical
 Light yellowish or greenish with hyaline cytoplasm
 Cyst wall has 2 membranes
 Reproduction – by transverse
binary fission (homothetogenic)
 conjugation may also take
place

6. LIFECYCLE
• Transmission is by cyst
• Commonly seen in lumen of
large intestine of pigs
• Pig is the usual source of
infection for man

7. PATHOGENESIS
 Opportunistic commensals
 Act as secondary invaders
 Produce hyaluronidase – enlarges already existing lesions
 May cause superficial to deep ulcerations – associated with
mild enteritis
 In man: pathogenic; diarrhoea and dysentery; produces
similar lesions to Entamoeba histolytica
 Ulcers – coagulative necrosis and haemorrhages

9. DIAGNOSIS AND
TREATMENT
 Detection of cyst in faeces or histological examination
 Clinical signs and post mortem – ulcerative condition of large
intestine and large numbers of Balantidium coli
 Treatment not necessary in pigs
 If acute, treated with tetracycline antibiotics
 Carbarsone, diiodohydroxyquinine, tetracyclines, paramycin,
metronidazole and imidazole can be used for human
balantidiosis

10. PREVENTION
 Purification of drinking water
 Proper handling of food
 Careful disposal of human feces and
pig faeces
 Monitoring the contacts of
balantidiasis patients

11. THANK YOU