Toxoplasma gondii dissemination: a parasite's journey through the infected host

Toxoplasma gondii is a highly successful global pathogen that is remarkable in its ability to infect nearly any nucleated cell in any warm-blooded animal. Infection with T. gondii typically occurs through the ingestion of contaminated food or water, but the parasite then breaches the intestinal epithelial barrier and spreads from the lamina propria to a large variety of other organs in the body. A key feature of T. gondii pathogenesis is the parasite's ability to cross formidable biological barriers in the infected host and enter tissues such as the brain, eye and placenta. The dissemination of T. gondii into these organs underlies the severe disease that accompanies human toxoplasmosis. In this review, we will focus on seminal studies as well as exciting recent findings that have shaped our current understanding of the cellular and molecular mechanisms by which T. gondii journeys throughout the host and enters organs to cause disease.