Tyzzeria Anseris

Hosts: Domestic goose, white-fronted goose (Anser albifrons), blue or snow goose (A. caerulescens), Ross's goose (A. rossi), Canada goose (Branta canadensis), Atlantic brant (B. bernicla hrota), whistling swan (Olor columbianus), lesser scaup duck (Nyroca affinis).

Location: Small intestine.

Geographic Distribution: North America, Europe.

Prevalence: This species is apparently rare in domestic geese, having been reported in them only by Nieschulz (1947) in Holland and by Farr and Wehr (1952) in Maryland. It is common, however, in wild geese, and has been found in all the species from which coccidia have been reported and from all 6 North American flyways (Hanson, Levine and Ivens, 1957). It is most likely a parasite of wild geese which occasionally occurs in domestic ones as the result of accidental contamination.

Morphology: The oocysts were described by Levine (1952). They are ellipsoidal, 10 to 16 by 9 to 12 u with a mean of about 13 by 11 u. The oocyst wall is smooth, colorless, about 0.6 u thick, and usually appears to be composed of a single layer altho in some oocysts a second inner line is visible; this may perhaps be a membrane which has pulled away from the wall. A micropyle is absent. The sporozoites are banana-shaped. The oocyst residuum is large, irregular, granular, and often surrounded by the sporozoites.

Life Cycle: Unknown.

Pathogenesis: Unknown in very young birds; negligible in adults.