Balantidium Coli PDF

BALANTIDIUM COLI MEDICAL PARASITOLOGY HABITAT Balantidium coli resides in the large intestine of man, pigs, and monkeys. TROPHOZOITE The trophozoite is actively motile and is invasive stage of the parasite found in dysenteric stool. It is a large ovoid cell, about 60–70 μm in length and 40...

BALANTIDIUM COLI MEDICAL PARASITOLOGY HABITAT Balantidium coli resides in the large intestine of man, pigs, and monkeys. TROPHOZOITE The trophozoite is actively motile and is invasive stage of the parasite found in dysenteric stool. It is a large ovoid cell, about 60–70 μm in length and 40–50 μm in breadth. The cell is enclosed within a delicate pellicle showing longitudinal striations. The motility of trophozoite is due to the presence of short delicate cilia over the entire surface of the body. Its anterior end is narrow and posterior end is broad. TROPHOZOITE 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). 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. CYST The cyst is 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. 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. Infection is acquired from pigs and other animal reservoirs or from human carriers. 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. LIFE CYCLE 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. LIFE CYCLE 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. PATHOGENESIS Clinical disease occurs only when the resistance of host is lowered by predisposing factors like malnourishment, alcoholism, achlorhydria, concurrent infection by Trichuris trichiura, or any bacterial infection. Clinical disease results when the trophozoites burrow into the intestinal mucosa, set up colonies, and initiate inflammatory reaction. This leads to mucosal ulcers and submucosal abscesses, resembling lesions in amoebiasis Unlike E. histolytica, B. coli does not invade liver or any other extraintestinal sites CLINICAL FEATURES Symptomatic disease or balantidiasis resembles amoebiasis causing diarrhea or frank dysentery with abdominal colic, tenesmus, nausea, and vomiting. Balantidium ulcers may be secondarily infected by bacteria. Occassionaly, intestinal perforation peritonitis and even death may occur. Rarely, there may be involvement of genital and urinary tracts. In chronic balantidiasis, patients have diarrhea alternating with constipation. LABORATORY DIAGNOSIS Stool Examination: demonstration of trophozoites and cysts in feces. (trophozoites in diarrheic feces & cysts are in formed stools) Biopsy: When stool examination is negative Culture: like Entamoeba histolytica, B. coli can also be cultured in vitro in Locke’s egg albumin medium or NIH polyxenic medium TREATMENT Tetracycline is the drug of choice and is given 500 mg, 4 times daily for 10 days. Alternatively Doxycycline can be give. Metronidazole and nitroimidazote have also been reported to be useful in some cases. PROPHYLAXIS Avoidance of contamination of food and water with human or animal feces. Prevention of human-pig contact. Treatment of infected pigs. Treatment of individuals shedding B. coli cysts.