Re-description of a genetically typed, single oocyst line of the turkey coccidium, Eimeria dispersa Tyzzer, 1929.

The Briston strain of Eimeria dispersa Tyzzer, 1929 was isolated originally from a commercial turkey flock from Briston, Norfolk, UK. A single oocyst-derived line of E. dispersa was propagated and used to re-describe biological and morphological features of E. dispersa in the turkey. Oocysts of the Briston strain measured 26 ± 1.1 μm (24-28) by 21 ± 1 μm (19-23); these were larger than oocysts described originally by Tyzzer in 1929 (22.75 by 18.84 μm) but within dimensions (26.07 by 21.04 μm) reported by Hawkins (1952) in his description of E. dispersa isolated from turkeys. In the present study, endogenous development started mainly in duodenum and upper jejunum and then spread down toward the lower jejunum. A few parasites were detected in the ileum beginning 96 h post-infection; only few gamonts were observed in the cecal neck area at 120 h, and no parasites were detected in cecal pouches or rectum. Four asexual generations were observed before the start of gametogony, and only one large type of first generation meront was detected in duodenum and upper jejunum at 32 h. This strain has a prepatent period of 120 h. The Briston strain of E. dispersa is a mildly pathogenic coccidium. Duodenum and jejunum of infected birds were slightly dilated and paler in color than of uninfected controls. There was whitish green mucoid material in the lumen of the duodenum and jejunum. The mucosa looked slightly congested and edematous with a few scattered petechial hemorrhages.