The cow has a brief period of vaginitis and infection spreads to the uterus. This parasite reproduces by longitudinal fission. Early abortion occurs 1 to 16 weeks after fertilization. If the fetus and all the fetal membranes are not excreted from the cow, the cow may die or become sterile. If the fetus and the membranes are passed the cow may become immune to the parasite.
Bulls serve as the carries.
The parasite can even survive in frozen semen.