Transformation of oocysts from several coccidian species by heat treatment

Abstract

The transformation of sporocysts in oocysts of Eimeria caviae, E. intestinalis, E. nieschulzi, E. separata, E. tenella, Isospora canis, I. heydorni, and Toxoplasma gondii by heat treatment was examined. Fresh unsporulated oocysts from these species were heated at 50 degrees or 55 degrees C for less than 5 min and cultivated at 25 degrees C for 1 week. No transformation of sporocysts was observed in the sporulated oocysts following heating at 55 degrees C, but sporulated oocysts of Tyzzeria and Caryospora types were found in some I. canis and I. heydorni oocysts after heating at 50 degrees C followed by cultivation. A few sporulated oocysts of the Isospora type were observed in E. intestinalis oocysts after cultivation. All transformed sporulated oocysts contained eight sporozoites. In contrast, the number of sporocysts varied from two to 0. These results indicate that sporocyst formation in oocysts was affected by heat treatment. The relationship between the total numbers of sporozoites and sporocysts in the transformed oocysts was consistent with that of the "Octozoic" group classified by Hoare.

Redescription of Genera of Family Eimeriidae Minchin, 1903

“…Besides, some species of coccidia can develop aberrantly under conditions of abnormal temperature or oxygen concentration. Under these changed conditions, a non-heritable change occurs in the numbers of sporocysts and sporozoites without any effect on their morphology and function (Cerna 1974;Lindsay et al 1982;Matsui et al 1989). been reported to shed oocysts of Eimeria in their feces, but their oocysts are not reported to infect these animals.…”