Sporozoites excyst and multiply asexually into clusters of tachyzoites that initiate cyst development in connective tissue. These cysts are spherical, white, glistening, and thick walled. They contain many thousands of PAS-positive bradyzoites and grow to several millimeters in diameter. The wall is often 10 microns thick or thicker. A live tissue culture adapted vaccine has been implemented in countries that are heavily infested with Besnoitia.
Treatment consists of isolating affected animals and symptomatic therapy.
Enteritis, subacute, diffuse, mild, with mucosal hyperplasia, multifocal villar blunting and fusion, crypt abscesses, microerosions, and epithelial and lamina proprial coccidian protozoa. This case was also reviewed by our consulting parasitologist, Dr. Chris Gardiner, who agreed that the organisms are consistent with an Eimeria sp. The cysts of Besnoitia characteristically have a thick hyaline wall with eccentrically placed host cell nuclei. The organisms in these sections have a thin, non-hyalinized wall and rare host cell nuclei. Rare macrogametes were noted within epithelial cells in some sections.