Synonym: Coccidium truncatum.
Hosts: Domestic goose, greylag goose (Anser anser), Ross's goose (A. rossi), Canada goose (Branta canadensis) (see Levine, 1953; Hanson, Levine and Ivens, 1957). In addition to these, Pavlov (1942) reported finding E. truncata in domestic ducks in Bulgaria, and Christiansen (1948, 1952) found oocysts resembling E. truncata but smaller in the kidneys of young swans (Cygnus olor) and common eiders (Somateria mollissima) in Denmark.
Geographic Distribution: Worldwide.
Prevalence: Relatively uncommon in domestic geese, at least in North America.
Morphology: This species has been described by Kotlan (1933) and Lerche (1923) among others. The oocysts are ovoid, with a narrow, truncate, small end, and measure 14 to 27 by 12 to 22 u. The oocyst wall is smooth and delicate, shrinking quickly during concentration in hypertonic solutions. A micropyle with a polar cap is present. An oocyst residuum is sometimes present. A sporocyst residuum is present. The sporulation time is 1 to 5 days.
Life Cycle: The endogenous stages occur in the epithelial cells of the kidney tubules. The life cycle has not been studied in detail. The prepatent period is 5 to 6 days according to Kotlan (1933).
Pathogenesis: E. truncata is highly pathogenic for goslings, sometimes wiping out whole flocks within a few days. The disease is usually acute, lasting only 2 or 3 days. Affected birds are extremely weak and emaciated. Their kidneys are greatly enlarged, light-colored, with small, yellowish white nodules, streaks and lines on the surface and thruout the parenchyma. The infected epithelial cells are destroyed, and adjacent, uninfected cells are also destroyed by pressure. The infected tubules are so filled with urates and oocysts that they are enlarged to 5 to 10 times the diameter of normal tubules.
Epidemiology: E. truncata occurs only sporadically in domestic geese in North America. It was first described in the United States by McNutt (1929) in Iowa, and has since been reported by Allen (1933) in Washington, D. C., Adler and Moore (1948) in Washington state, Levine, Morrill and Schmittle (1950) in Illinois, Lindquist, Belding and Hitchcock (1951) in Michigan, Farr and Wehr (1952) in Maryland, and McGregor (1952) in Ontario. It has also been found in New York and Quebec.
The epidemiology of E. truncata in wild geese is especially interesting (Hanson, Levine and Ivens, 1957). It has been found in the greylag goose (Anser anser) in Europe by Christiansen and Madsen (1948), and in Ross's goose (A. rossi) and the Canada goose (Branta canadensis) in North America. However, of the 6 wild goose flyways which form vertical bands across North America, E. truncata has been found only in the South Atlantic and Pacific flyways, and not from the flyways in between. It is common among Canada geese of the South Atlantic flyway, and has been associated with losses at their winter quarters at Pea Island, North Carolina (Critcher, 1950). Its apparent absence from wild geese in the interior flyways does not seem due to the examination of too few birds, since Hanson, Levine and Ivens (1957) failed to find it in 258 wild geese from these flyways altho they recognized it in birds from both coasts. Perhaps E. truncata was originally a parasite of greylag and domestic geese in Eurasia and has reached North American wild geese relatively recently, entering from both the east and west.