Submitted to: International Journal for Parasitology
Publication Type: Review Article
Publication Acceptance Date: April 6, 1998
Publication Date: N/A
This paper reviews recent studies on the life cycle of Toxoplasma gondii. Tachyzoites, bradyzoites, and sporozoites are the three infectious stages of T. gondii. Humans and animals become infected mainly by ingesting bradyzoites or oocysts. After ingestion, both bradyzoites and sporozoites convert to tachyzoites inside tissues of humans and animals. The conversion of tachyzoites to bradyzoites and bradyzoites to tachyzoites is of biologic and clinical significance because bradyzoites are less susceptible to chemotherapy and reactivation of bradyzoites to tachyzoites is considered the cause of fatal toxoplasmosis in AIDS patients. Of all the methods currently available to study stage conversion of T. gondii, feeding infective stages to cats is the most reliable method. Felidae, the definitive host of T. gondii excrete oocysts 3 to 10 days after ingesting tissue cysts/bradyzoites, ò18 days after ingesting oocysts, and ò13 days after ingesting tachyzoites.