Myopathy associated with megaloschizonts of Haemoproteus meleagridis in a wild turkey from Florida.

Necropsy of an emaciated adult wild turkey (Meleagris gallopavo osceola) that died in captivity soon after capture revealed numerous macroscopic 1-2 mm white cysts in the pectoral muscles. Microscopic, aseptate protozoan megaloschizonts, 50-150 microns in diameter, corresponded to the cysts in histological sections. The megaloschizonts were surrounded by a thick, hyaline wall and packed with spherical merozoites less than 1 micron in diameter. Muscle fibers surrounding most of the megaloschizonts exhibited early signs of dystrophic calcification. The fibers were swollen, pale and hyaline and contained scattered basophilic granules. The megaloschizonts were morphologically distinct from sarcocysts of Sarcocystis sp. and Besnoitia sp. and the thin-walled tissue cysts of Toxoplasma gondii. They were identical in structure and host reaction to the second-generation megaloschizonts of Haemoproteus meleagridis, reported previously from experimentally infected domestic turkeys. While the precise cause of death of the wild turkey could not be determined, the most prominent lesions were associated with the numerous intramuscular megaloschizonts.