The evolution of the knowledge of cat and dog coccidia.

Before the discovery of Toxoplasma gondii as a coccidium of the cat in 1970, cat and dog coccidia were classified in the genus Isospora and considered of little clinical or zoonotic significance. Since 1970, several new (Hammondia sp., Neospora sp.) and previously described species, including Sarcocystis, Besnoitia, and Cryptosporidium have been found as coccidians of cats and dogs with clinical and zoonotic significance. In the present paper I review salient features of the evolution of cat and dog coccidia.