Download THE MEDICALLY IMPORTANT CILIATES )Balantidium coli

Mustafa HA. Rasool
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THE MEDICALLY IMPORTANT CILIATES
)Balantidium coli(
Mustafa HA. Rasool
MLT Dep. HHTC, EPU
Balantidium coli
Introduction:
They possess simple cilia or compound ciliary organelles, two types of nuclei and a
large contractile vacuole. The only member of the ciliate family to cause human disease is
Balantidium coli which is widely distributed in warmer climates, the organisms inhabit the
large intestine, cecum and terminal ileum where they feed on bacteria .
The most common hosts being humans, pigs and rodents. Disease produced by B. coli
is named balantidiasis, it is similar to amebiasis, because the organisms elaborate proteolytic
and cytotoxic substances that mediate tissue invasion and intestinal ulceration.
Mustafa HA. Rasool
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Morphology
1- Trophozoite:
Trophozoites of B. coli measure approximately 30-150μm in length x 25-120μm in
width. They are oval in shape and covered in short cilia. Multiplication is by binary fission in
the trophozoite stage. In an unstained preparation, the organisms are easily recognized
because of their size and rapid revolving rotation. In a stained preparation, the characteristic
macro and micronuclei may be observed.
1-
Cyst
The cyst is spherical and measures from 30-200μm by 20-120μm. It contains 1 macro and 1
micronucleus. The cilia are present in young cysts and may be seen slowly rotating, but after
prolonged encystment, the cilia disappear. Cysts form when diarrhea subsides and the
rectalcontents become formed.
Mustafa HA. Rasool
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Life cycle
The life cycle of B. coli is simple, involving ingestion of infectious cysts, excystation,
and invasion of trophozoites into the mucosal lining of the large intestine, caecum, and
terminal ileum. The trophozoite is covered with rows of hair like cilia that aid in motility.
Morphologically more complex than amebae, B. coli has a funnel-like primitive mouth called
a cytostome, a large (macro) nucleus and a small (micro) nucleus involved in reproduction.
Life cycle
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Clinical features (Symptoms)
As with other protozoan parasites, asymptomatic carriage of B. coli can exist .
Symptomatic disease is characterized by:
( abdominal pain, tenderness, tenses, nausea, anorexia, and watery stools with blood
and pus. Ulceration of the intestinal mucosa), as with amebiasis, can be seen; a secondary
complication caused by bacterial invasion, intestinal invasion of organs is extremely rare in
balantidiasis.
Treatment
The drug of choice is tetracycline; iodoquinol and metronidazole are alternative agents.
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Microsporidia
Are a group of protozoa characterized by obligate
intracellular replication and spore formation.
Enterocytozoon bienusi and Septata intestinalis are two important microsporidial species that
cause severe, persistent, watery diarrhea in AIDS patients.
The organisms are transmitted from faecal-oral route. It is uncertain whether an animal
reservoir exists.
Diagnosis is made by visualization of spores in stool samples or intestinal biopsy samples; the
drug of choice is albendazole.
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Mustafa HA. Rasool
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Sporozoa or coccidia
Coccidia are members of the class sporozoa, The life cycle is characterized by an
alternation of generations, i.e. sexual (gametogony) and asexual (schizogony) reproduction
and most members of the group also share alternative hosts.
The locomotion of a mature organism is by body flexion, gliding, or undulation of longitudinal
ridges.
Divided into two groups:
A\ Intestinal sporozoa, which include:
1- Cryptosporidium parvum.
2- Isospora belli.
3- Cyclospora cayetanensis.
B\ Blood and tissue sporozoa: which include:
1- Plasmodium spp.
2- Toxoplasma gondii
3- Babesia spp .
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Cryptosporidium parvum,
Causes cryptosporidiosis ,
Symptom\ diarrhea. It is most severe in immunocompromised patients, e.g., those with AIDS.
The organism is acquired by faecal-oral transmission of Oocysts from either human or animal
sources. The oocysts excyst in the small intestine, where
the trophozoite (and other forms) attach to the gut wall. Invasion does not occur. The
jejunum is the site most heavily infested. No toxin has been identified.
Cryptosporidium causes diarrhea worldwide, for large outbreaks of diarrhea caused by
Cryptosporidium are attributed to inadequate purification of drinking water. The disease in
Mustafa HA. Rasool
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immunocompromized patients presents primarily as a watery, non-bloody diarrhea causing
large fluid loss.
Isospora belli
Is an intestinal protozoan that causes diarrhea, especially in immunocompromised
patients, e.g., those with AIDS .
The organism is acquired by fecal-oral transmission of oocysts from either human or animal
sources. The oocysts excyst in the upper small intestine and invade the mucosa, causing
destruction of the brush border.
The disease in immunocompromised patients presents as a chronic, profuse, watery
diarrhea.
The treatment of choice is trimethoprim-sulfamethoxazole.
Cyclospora cayetanensis
Is an intestinal protozoan that causes watery diarrhea in both immunocompetent
and immunocompomised individuals. It is classified as a member of the Coccidian; the
organism is acquired by fecal – oral transmission, especially via contaminated water supplies .
There is no evidence for an animal reservoir. The diarrhea can be prolonged and relapsing,
especially in immunocompromized patients. Infection occurs worldwide .
The treatment of choice is trimethoprim-sulfamethoxazole.
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