Parental development of Eimerian coccidia in sandhill and whooping cranes

In contrast with isosporoid species of coccidia that have established extraintestinal phases of development, the eimeriids, except for a few species, generally have been considered inhabitants of the intestinal tract. Eimeria infection in sandhill cranes (Grus canadensis) and whooping cranes (G. americana) may result in disseminated visceral coccidiosis. Nodules were observed in the oral cavity of 33% (n = 95) of the G. canadensis at the Patuxent Wildlife Research Center (PWRC) in Laurel, MD. Necropsy of six of the afflicted cranes revealed granulomatous nodules in many tissues and organs. Histologic studies disclosed protozoan organisms morphologically resembling schizonts in the granulomas, and endogenous stages of coccidia were present in the intestines of four birds. Fecalysis of three of four sandhill cranes yielded oocysts of E. reichenowi and E. gruis. Only E. reichenowi-type oocysts were recovered from a dead whooping crane sample. Domestic broiler chicks each intubated with about 1 times 10⁶ pooled sporulated oocysts of E. reichenowi and E. gruis were not infected. Exposure of six incubator-hatched and hand-reared sandhill crane chicks to oocysts artificially (two chicks) and naturally (four chicks) resulted in typical infection of intestinal epithelium with invasion of subepithelial tissues extending to the muscular layer and widespread extraintestinal development. Asexual and sexual stages occurred primarily in macrophages in the liver, spleen, heart, and lung. In the lung, oocysts were found in bronchial exudate and epithelial lining cells. Six of ten G. canadensis chicks, one adult G. americana, and three of five G. americana chicks that died naturally at PWRC had disseminated visceral coccidiosis.