Balantidium coli

Classification, morphology, lie cycle,pathogenesis and lab diagnosis

1. Balantidium coli

2. Classification Kingdom- Protista Sub-kingdom-Protozoa Phylum- Ciliophora Class- Kinetofragminophorea ( Litostomatea ) Order- Trichostomatida ( Vestibuliferida ) Family- Balantidiidae Genus- Balantidium Species- coli

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

8. Geographical distribution But also reported in Norway, Sweden, Finland, and northern Russia

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, In South America the prevalence rate was 1 to 12% in late nineties Nearly, 30% cases in Oceania in 2013 West Irian district of Indonesia, prevalence rates has been reported upto 20%

10. Epidemiology It frequency of occurrance is less reported from Indin 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 Trophozoite It measures from 30 µm to 300 µm in length and its breadth varies from 30 µm 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: A large kidney shaped Situated in the middle of the body Micronucleus: 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 Cyst: Round and smaller than trophozoit Contains single cell inside cyst Measures 40 µm 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

18. Figure: Trophozoite Figure: Cyst

19. Life-cycle

20. 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

21. 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

22. 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

23. 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

24. Life-cycle

25. 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

26. 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 Mechanical action by ciliary movement of the trophozoite Production of hyaluronidase by parasite Invades mucosa and sub-mucosa causing ulcers

27. Pathogenesis Ulcers: Ulcers are similar to that of intestinal amoebiasis Found in caecum , ascending colon, sigmoid colon and rectum Oval or round in shape Are multiple in numbers having undermined edges Floor of ulcers contains pus and necrotic materials

28. 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

29. Pathogenesis

30. Clinical manifestation Generally, it is a self-limiting and asymptomatic infection Causes Balantidiasis or ciliate dysentery Diarrhoea alternating with constipation is typical symptoms in mild infection 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

31. 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

32. Intestinal perforation and extra-intestinal infection are rarely seen

33. 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

34. Laboratory Diagnosis Molecular technique: Genetic analysis by sequencing, PCR Sigmoidoscopy Serological test: Immuno -assay, Immuno - fluorescent assay and ELISA

35. 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

36. Prognosis Recover occurs without treatment Severe and fatal in malnourished and immuno -compromised patients

37. 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

38. 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

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