An outbreak of histomoniasis in turkeys infected with a moderate level of Ascaridia dissimilis but no Heterakis gallinarum

Histomoniasis was diagnosed in a commercial turkey flock. All morbidity and mortality occurred in one house. Birds exhibited lesions characteristic fo r histomoniasis, and the diagnosis was confirmed by histopathologic examina tion. Affected turkeys were infected with moderate levels of Ascaridia diss imilis but not Heterakis gallinarum, Compression smears of hepatic tissues showed typical histotrophic phase Histomonas meleagridis, whereas cecal sme ars exhibited large numbers of Trichomonas gallinarum. A challenge experime nt was conducted in which turkey poults were placed on contaminated litter. Although histomoniasis was not reproduced in the experiment, the birds did become infected with low numbers of A. dissimilis.