Synonyms: Fibrocystis tarandi Hadwen, 1922.
Disease: Besnoitiosis, corn-meal disease.
Hosts: Reindeer, caribou.
Location: The cysts occur in the fibrous connective tissues, especially in the periosteum and on the surface of the tendons.
Geographic Distribution: Alaska.
Prevalence: Hadwen (1922) found this parasite in a number of herds of reindeer and in caribou in Alaska.
Morphology: The cysts are spherical and 100 to 450 u in diameter with a mean of 275 u. They are composed of 3 layers, of which the outermost is thick and fibrous, with concentrically arranged fibers, the middle layer is clear and hyaline, and the inner layer forms a thin lining. The cysts are not compartmented. The cyst contents are dark brown. The trophozoites are spindle shaped, with a central nucleus, and measure 7 by 1.8 u in alcohol-fixed material.
Life Cycle: Unknown.
Pathogenesis: Reindeer owners call besnoitiosis "corn-meal disease" because of the granular nature of the lesions. The cysts may be found in the periosteum of all of the bones. When the periosteum is stripped off, small pits corresponding to their position are found in the bone itself. They are also found on the surface of the tendons, where they cause similar pits.