For years, toxoplasmosis has been known as a disease that mostly affects newborns who have acquired Toxoplasma gondii in utero. This parasite has gained increasing interest, because of immunocompromised patients, such as those suffering from AIDS, who present a high risk of reactivation of chronic toxoplasmosis, which can eventually result in fatal cerebral disease.

The objective of this book is to inform scientists, clinicians, and students of our current knowledge of the interaction between Toxoplasma gondii and its animal or human host.

Recent progress in the development of in vivo and in vitro models and the advent of genetic manipulation has made research of Toxoplasma gondii an evolving area and a model for other protozoan parasites. The chapters of this volume include recent findings on antigens and genes of Toxoplasma gondii and the parasite's interaction with the hosts's immune response.

Using new technologies, investigations on the developmental differentiation of the parasite have become possible and this knowledge will help us to understand the basis of pathogenesis and persistence of intracellular parasites. Finally, advances in molecular biology and identification of drug targets might lead to new concepts in diagnosis and treatment.