A Neospora-like protozoon found in an aborted bovine placenta.

Portions of the placenta and kidneys from a 5-month-old bovine fetus were examined histologically. The placental cotyledonary villi were necrotic and protozoa were found in lesions. The organisms were in trophoblasts, periodic acid Schiff-negative and did not react in an immunoperoxidase test using anti-Toxoplasma gondii serum. Individual zoites were approximately 5 x 2 microns and the biggest collection was 45 x 35 microns. The organism in the present case was structurally distinct from Sarcocystis spp. and Toxoplasma gondii, but resembled Neospora caninum.