4. Tripozoit Chilomastix mesnili

Ciri-ciri:- Bentuk jambu monyet- Inti 1 dengan karyosom- Punya 3 flagel anterior dan 1 flagel halus dalam sitostoma- Meruncing di bagian posterior

Chilomastix mesniliIntroductionChilomastix mesnili is cosmopolitan in distribution although found more frequently in warm climates. It is thought to be non-pathogenic although the trophozoite has been associated with diarrhoeic stool. This is the largest flagellate found in man with an incidence of 1-10% being in the large intestine.(Diag 6 illustrates the life cycle of C. mesnili)

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Morphology of the Trophozoite The trophozoites of C. mesnili are pear shaped and measure 6-20 m in length. They have 1 large nucleus with a small karyosome and 3 flagella that extend from the nucleus at the anterior end of the parasite. A distinct oral groove or cytosome can be seen near the nucleus with its sides being supported by two filaments. They are known to move in a directional manner. (Diag 7 & Fig 7)

Morphology of cysts The cysts are 6-9 m, they have a large single nucleus with a large karyosome. They also have a prominent side knob giving it a characteristic lemon shape. (Diag 8 & Fig 8) The cytosome is evident with a curved shepherds crook fibril. It also has a characteristically coiled filament which when stained is darker in colour.

Fig 8. Chilomastix mesnili cysts are excreted with faeces and constitute the transmission form of the micro-organism. The uninucleated lemon shaped cysts are seen with a little proturberance at one end and a prominent cytostome. (Iodine stained). (6 m) (www.dpd.cdc.gov)Laboratory DiagnosisThe characteristic lemon shaped cysts can be seen in a formol-ether concentrate. (Fig 8) Motile organisms can be seen in a wet preparation of a fresh stool however the characteristic morphology is evident in a permanently stained preparation. (Keys 1 & 2) Table 1 (page 17) details useful morphological features that are similar between species of flagellate and are used in laboratory diagnosis