The zygote will then encyst to form an oocyst. The oocyst pass in feces and can now infect a new host. An infective oocyst is ingested by some mammal other then cats. The sporozoites are released and begin to penetrating intestinal epithelial cells and muscle tissue. When the zoites slowly divide in other tissue they are called bradyzoites.
Chronic infection occurs when the host's immune system decreases the formation of tachyzoites.
This parasite is a serious opportunistic infection in AIDS patients. When a pregnant women becomes infected it can cause congenital toxoplasmosis in the developing fetus. This can cause spontaneous abortion in the first trimester or serious birth defects. Also, it can cause severe retardation in the infant. The drugs pyrimethamine and sulfonamides given together help against this parasite.