Increase in Size of Eimeria separata Oocysts during Patency

Abstract

Examinations of 18 consecutive fecal samples collected at 6-hr intervals from infected rats showed that oocysts increased in length and width by approximately 40% from the beginning to the end of the patent period. Unsporulated oocysts were first observed in the 3rd fecal collection, 84 to 90 hr post-inoculation (PI) and 100 of these measured 9.9 to 14.3 by 8.8 to 12.1 μ (mean 11.7 by 10.1). Patency ended with the 15th fecal collection, 156 to 162 hr PI, and 100 unsporulated oocysts from this sample measured 14.3 to 17.6 by 13.2 to 15.4 μ (mean 16.3 by 14.2). Despite the size increase during patency, oocyst shape-index did not change. Sporulated oocysts did not differ significantly from unsporulated oocysts in length or width. The most significant increases in both length and width of the sporulated oocysts occurred 90 to 96 and 120 to 126 hr PI.