Date of Award:

5-1-1958

Document Type:

Thesis

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Zoology

Committee Chair(s)

Datus M. Hammond

Committee

Datus M. Hammond

Committee

Eldon J. Gardner

Committee

Merthyr L. Miner

Committee

Joseph L. Thorne

Committee

LeGrand Shupe

Abstract

Coccidiosis is a disease which can occur in most vertebrates and certain invertebrates as a result of infection by organism classified in the Order Coccidia of the Class Sporozoa, Phylum Protozoa. Host animals become infected by ingesting the exogenous resistant stage, the oocyst (Figures 1 and 2). These oocysts may be ingested with contaminated food and water or from the bodies of other animals. In the intestine of the new host, the oocysts rupture and release a specific number of sporosoites depending upon ths genus of coccidia involved. The liberated sporesoites penetrate epithelial or other cells of the intestine and produce schizonts (Figures 3, 4, and 5). In the schizont stage, an asexual multiplication occurs which results in the production of a large number of merozoites. After being released into the lumen of the intestine by rupture of the schizont, the merozoites penetrate other cells where they may produce another asexual generation or the sexual stages depending upon the species of coccidia involved. The sexual stages consist of the microgamete, or male sexual stage, and the macrogamete, or female sexual stage (Figures 6 and 7). The microgametes are formed in microgametocytes, the number per microgametocyte again dependent upon species. The macrogametes are formed directly from the merozoites. The macrogametes become surrounded by a resistant wall after fertilization and are then called oocysts (Figure 1). These oocysts rupture the host cell and are discharged with the fecal material. Oocysts are not infective until they have undergone a further developmental process called sporulation. during sporulation the zygote within the oocyst wall divides into a specific number of sporoblasts which become surrounded by a spore wall. The protoplasm within the spores then divides to produce sporozoites. Oxygen, moisture, and a temperature of 15 to 30° C. are necessary for this process. Large numbers of intestinal cells are destroyed as the oocysts are released and the symptoms of coccidiosis are correlated with this destruction.

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