Lecture #14: SUBPHYLUM CILIOPHORA

******  BALANTIDIUM COLI  ******

–        Balantidiasis may be asymptomatic or it may produce severe diarrhea and dysentery indistinguishable clinically from acute amoebic dysentery.

–        the largest intestinal protozoan in man and the only pathogenic ciliate causing balantidiasis or balantidial dysentery.

Morphology:

1.      Trophozoite

a.      50–100u x 40–60u

b.      Move by means of cilia, which are of uniform length and cover the entire organism. They exhibit directional, tumbling motion.

c.       The organism is more pointed at the anterior end and has 2 nuclei, a kidney–shaped macronucleus and a small spherical micronucleus.

d.     Contractile vacuoles and food vacuoles are present.

e.      It is greenish yellow when unstained.

2.      Cyst

a.      45 – 65u

b.      Round with a thick wall having a double outline.

c.       Only macronucleus, contractile vacuoles and cilia are present.

d.     Stains poorly due to thick cell wall.

e.      This the infective stage.

f.        Macronucleus and contractile vacuole are visible in young cysts. In older cysts, internal structures appear granular.