Pathogenicity of a strain of Trichomonas gallinarum in turkeys and its possible interaction with cecal coccidia.

The pathogenicity of Trichomonas gallinarum (TG) in turkeys and chickens was assessed in a series of four experiments. TG was shown to be resistant to freezing for a period of 1 hr at -20 C; birds administered an emulsion of previously frozen TG were readily infected. Young birds receiving this inoculum were more likely to be infected with TG in both ceca compared with birds administered TG emulsion that had remained at room temperature for the same length of time. In this and other experiments, birds infected with the parasite consistently produced a yellow frothy liquid in the ceca, as well as small raised papulae on the mucosal surface of the ceca. Histologically, the lesions were located in the lamina propria, with openings that extended from the apex of the lesion to the crypts. The lamina propria was consistently infiltrated by lymphocytes and scattered heterophiles. Although TG is likely involved in the pathogenesis of the lesions, the resulting pathology could not be linked definitively to TG alone because inoculation was performed with a cecal contents homogenate containing significant numbers of cecal bacteria. Combined infections of TG and Eimeria adenoides (EA) were also studied. Turkeys administered both parasites were more frequently infected with TG in both ceca compared with those that received TG alone. Ceca infected with TG alone tended to be enlarged and gas filled, whereas those infected with the combination of TG and EA were smaller and usually lacked the yellow frothy liquid contents.