Immune responses to Toxoplasma gondii in the gut.

Toxoplasma gondii is an important cause of disease, in pregnant women, newborns and immunocompromised hosts. Infection with T. gondii naturally occurs through ingestion of raw or undercooked meat containing cysts or through contact with cat feces containing oocysts. The intestine thus appears to be the site of invasion of the parasite. Since acute infection in immunocompetent hosts usually goes unnoticed, no information is available regarding the involvement of the intestine during acute infection in humans. However, in murine models of the disease the acute phase of infection has not been investigated in detail as well. In this report, an overview of the current knowledge regarding the initial phase of infection with T. gondii is given. Results of studies focussing on invasion and dissemination of the parasite and the immune responses elicited in the intestine are reviewed. The impact on the induction of local immune responses of the genetic background and sex of mice as well as the role of different doses and strains of the parasite are discussed. Finally, reports on the development of intestinal pathology in different animal species and the involvement of the intestine in human disease are reviewed.