Location: Duodenum, jejunum, ileum.
Geographic Distribution: North America (United States), Europe (England, Holland, Austria, Italy), South Africa.
Prevalence: Unknown. Becker and Frye (1927) found this species in the feces of cattle in Iowa, Nieschulz (1923) saw it in a calf in Holland, Graham (1935) found it alive and active in the digestive tract of 6 of 21 female Cooperia oncophora from a calf from New Jersey, and we have found it from time to time in casual examinations in Illinois.
Morphology: The trophozoites are 11 to 19 u long and 7 to 10 u wide. The median bodies are curved bars of the duodenalis type. The cysts are 7 to 16 u long and 4 to 10 u wide.
Pathogenesis: The pathogenicity of G. bovis is unknown. Supperer (1952) found it in a calf in Austria with a mucous diarrhea. The calf was killed for necropsy diagnosis and was found to have catarrhal duodenitis and jejunitis; the mucosa was dark red, thickened and lay in folds. Botti (1956, 1956a) found it in calves with hemorrhagic diarrhea in Italy. On the other hand, the cattle in which we saw the organism in Illinois did not appear to be affected by it.