Ciliophora

They are group of protozoa characterized by head like structure called cilium which is important in A – movement B - nutrition .

This parasite have two species :-

Balantidium suis infect the pigs .

Balantidium coli infect the human .This disease is regarded as a zoonotic disease .Disease : BalantidiosisB.coli :- is the largest intestinal protozoa that effect human and can be seen macroscopically .

Morphology :- the parasite is observed in two stages only which are-: A – trophozoite-:

1 -Large size (40 µm to more than 70 µm). 2 -called the invasive stage.

3 -ovoidal in shape. 4 -covered by cilia & the anterior end are longer

than the posterior end.

5 -in the anterior end there is mouth called cytosome .

6 -the internal structures-: A- have two nuclei , the macronucleus

(the largest one) & micronucleus (the smallest

one ) . B- the macronucleus is kidney or bean in

shape . C- the micronucleus is small spherical

shape located in the concavity of

macronucleus . D- have two secretory contractile

vacuoles. E- numerous food vacuoles .

B- Cyst-:

1 -typically spherical in shape. 2 -surrounded by thick wall (one or two

layers ) by encystation in small intestine to protect the

parasite from the host.

3 -contain the macronucleus and contractile vacuoles are

visible in the cyst.

4 -the cilia are undetectable , only the roots may present.

Multiplication :- occur by two method 1 -Asexual type by binary fission.

2 -Sexual type by conjugation.

Life cycle :- direct life cycle or simple life cycle that mean the parasite not need for intermediate host. Mature cysts are passed with feces.

Transmission :- by ingestion of contaminated food or water (NOT in undercooked meat) with feces contain the

mature cyst.   Excystation occurs in the small intestine, and the

trophozoites colonize in the large intestine . Trophozoites undergo encystation to produce infective cysts.

Cysts are the infective stage of this parasite .