Besnoitia species (Protozoa, Sporozoa, Toxoplasmatidae): recognition of cyclic transmission by cats.

Isosporan oocysts, measuring 13 by 16 micrometers, from a cat in Hawaii produced Besnoitia cysts in tissues of mice and rats. Feeding these cysts to cats led to oocyst shedding after 11 to 13 days, continuing for a mean of 11 days. This indicates a two-host cycle for Besnoitia, adding an intestinal phase and oocyst production by a carnivore to the already known tissue stages. Thus a representative of Besnoitia, similar to other species in cattle, horses, reindeer, impala, other mammals, and reptiles, has been shown to be a coccidian of cats, capable of being spread by fecal contamination. Besnoitia is the fourth mammalian tissue parasite, together with Toxoplasma, Hammondia, and Sarcocystis, found to produce isosporan-type oocysts.