2 Typical postmortem findings include a bird in good body condition with clear fluid exuding from the mouth when the bird is lifted. The liver and spleen usually are enlarged. 2 Microscopically, the lungs will typically be congested with some fibrin deposition, edema, and hemorrhage within parabronchi. Meronts may be observed within pulmonary capillary endothelium. In addition, free merozoites may be observed within the pulmonary capillary lumina or in the parabronchi in association with hemorrhage.
Merozoites are elongate, crescent-shaped, and contain a single, prominent, basophilic nucleus.
The number of merozoites observed in histologic sections may range from rare to numerous. In severe infestations, the merozoites may obstruct pulmonary capillaries. In addition to histopathology, Romanowsky-stained cytologic touch imprints of unfixed lung tissue may facilitate disease diagnosis by demonstrating individual merozoites. Sarcocysts occur in skeletal and cardiac muscle, are variably-sized, and may have a striated cyst wall. Meronts also may be observed in monocyte-macrophages in the spleen, liver, pancreatic islets, and proventriculus.