Family Cochlosomatidae

In this family there are 6 anterior flagella, an axostyle, an anteroventral sucker, and a single nucleus. There may or may not be a parabasal body. The only genus so far reported from domestic animals is Cochlosoma, but Cyathostoma Tyzzer, 1930 and Ptychostoma Tyzzer, 1930 have been described from the ruffed grouse (Bonasa umbellus) in North America.

Genus Cochlosoma

The body is ovoid, broadly rounded anteriorly and narrowly rounded posteriorly. Six flagella of unequal length arise from a blepharoplastic complex at the anterior end; 2 of them are trailing and lie in a longitudinal groove. The nucleus is near the middle of the body. A slender, fibrillar axostyle and a more lateral costa arise from the blepharoplastic complex. On the anteroventral surface is a large sucker which opens on the left side and has a marginal filament. A parabasal body is present.

Cochlosoma anatis Kotlan, 1923 (syn., Cochlosoma rostratum) occurs in the cloaca, large intestine and sometimes the ceca of the domestic duck, Muscovy duck and also in the wild mallard and various other wild ducks. It has been reported in Hungary by Kotlan (1923), in California by Kimura (1934), in Iowa by Travis (1938), and is probably worldwide in distribution. Kimura (1934) found it in 23 of 30 White Pekin and Muscovy ducks in central California.

The body of C. anatis is beet-shaped, 6 to 12 u long and 4 to 7 u wide. The sucker covers 1/3 to 1/2 the body length. The organism swims forward with an erratic, jerky motion, rotating on its long axis but with very little of the dipping motion of Giardia. The parabasal body is sausage-shaped. Reproduction is by longitudinal fission. C. anatis has not been cultivated.

The pathogenicity of C. anatis in waterfowl is unknown. Kimura (1934) found it in both healthy and sick birds, but the condition of the latter was due to bacterial or nutritional disturbances, and even in heavy Cochlosoma infections there was no intestinal inflammation. Travis (1938) found no lesions in the infected domestic and wild ducks which he examined.

McNeil and Hinshaw (1942) reported finding a Cochlosoma morphologically indistinguishable from C. anatis in turkeys in California. In young poults it was present thruout the intestinal tract, and in adults in the region of the cecal tonsil. Campbell (1945) found Cochlosoma in large numbers in the intestinal tracts of a flock of young turkeys in Scotland affected with a disease clinically and pathologically indistinguishable from infectious catarrhal enteritis due to Hexamita meleagridis. Both McNeil and Hinshaw and Campbell considered the turkey form to be the same species found in ducks, but experimental and further morphological studies are needed to be sure of this.

It has not been established whether this form is pathogenic for turkeys. Campbell believed that it was the cause of the enteritis which he saw, but Hexamita was also usually detectable in his affected birds. In the turkey poults studied by McNeil and Hinshaw, Cochlosoma was always found in association with Hexamita or with Hexamita and Salmonella.