1. Terms Used in Relation to Ciliates Cilia Infraciliature Contractile vacuole Cytostome Macronucleus Micronucleus Conjugation Kinetosome Kinety

2. Pathogenic intestinal ciliate Balantidium coli 大腸纖毛蟲 Geographical distribution The only ciliate infects man Sporadic infections in many place Endemic area is New Guinea Close association between man and pigs

3. Morphology Trophozoite stage: reniform large macronucleus Smaller micronucleus in the concavity of macronucleus 30-300 μm in size, 2 contractile vacuoles Cytostome locate at anterior end as funnel-shape Locomotion with cilia, embedded in pellicle in longitudinal rows these rows (kineties) can be seen under phase contrast or interference contrast microscopy or by silver staining Cystic stage: spherical or ovoid, 40-60 μm in diameter Thick and transparent cyst wall The cilia get absorbed Contractile, macro- and micro- nucleus, other structures are similar to trophozoites Balantidium coli

4. Sliver stain

5. Balantidium coli Trophozoite Cyct

6. Balantidium coli Trophozoite Conjugation Binary fission

7. Life cycle Infection occurs from close association with pigs Human to human transmission may also occur Cyst is the infective stage of this parasite Excystation occurs in small intestine Multiple in large intestine by binary fission Conjugation at the anterior end for a few minutes Balantidium coli

8. Clinical Aspects Balantidiasis: 大腸纖毛蟲症 Similar to amoebiasis in pathology and clinical symptoms No extraintestinal pathogenesis Trophozoites are often located in the submucosa of infected intestine Balantidium coli

9. Diagnosis Faeces examination Trophozoites or cysts Actively motile trophoozites in acute dysentery( 痢疾 ) Easy to recognised by their characteristic macronucleus Balantidium coli

10. Treatment Drgus: Oxytetracycline: 30 mg/kg body weight/day in divided doses 6-hour for 10 days Metronidazole: same as amoebiasis Balantidium coli