Chapter 4 PHYLUM CILIOPHORA

 

 

4.1 THE CILIATES

4.1.1 GENERAL INFORMATION :

I. Characteristics of Ciliates

• A. Ciliates, with few exceptions, have a macronucleus and a micronucleus
• B. All have simple cilia or fusion of cilia to form cirri or membranelles
• C. All have a complex skeleton-like system of fibrills beneath the membrane (infraciliature)
• D. Reproduction is asexual by transverse binary fission or sexual by conjugation
• E. Most are free-living but a few are parasitic or mutualistic 

4.1.2 BALANTIDIUM AND ICHTHYOPHTHIDIUS 

4.1.2.1 Balantidium spp. 

Normally commensal inhabitants of the cecum and colon of man and other animals. On rare occasions, they may invade the mucosa and cause balantidial dysentery. Balantidiun coli is the most important species.

4.1.2.1.1 Classification

• 1. Phylum Ciliophora
• 2. A number of species of Balantidium have been named many wrongly so. We will refer to all important species as B.coli.

4.1.2.1.1 Geographic distribution:

worldwide. Balantidium coli has been found in man, pigs, subhuman primates and rarely in the dog.

4.1.2.1.2 Epidemiology:

Balantidium coli is transmitted most commonly as the resistant cyst stage. Several workers insists that transmission may also occur in the trophozoite stage.

4.1.2.1.4. Life cycle:

For the terminology and morphology of the different stages, See Figures 2.21 and 2.22. Though most ciliates are nonpathogenic commensals, often after the host dies, they move to the liver via mesenteric veins or into tissue of the intestinal tract and may be mistaken for pathogens. These ciliates commonly have an elongate nucleus, which is round in cross section.

 

Figure 2.21: Morphology of Balantidium coli

 

4.1.2.2 Ichthyophthirius spp.

Ichthyophthirius spp. are pathogens of fish. Trophozoites of Ichthyopthirius spp. may penetrate the skin and produce "Ich" or white spot disease. The trophozoites eventually develop a cyst wall, drop off the fish, and enter the water, where they rupture and release trophozoites that reinfect other fish. Ichthyophthirius spp are 75 um to 1 mm in diameter, are uniformly ciliated, and have a crescent-shaped nucleus.