Toxoplasmosis is a serious disease in humans where it can cause abortion or congenital infection if a women is exposed to disease for the first time during pregnancy. Infection prior to pregnancy normally results in immunity and which is capable of protecting the foetus. Similar observations have been made in the BALB/c mouse indicating the potential of mice for studying congenital disease. Consequently, the mouse has been used to study how mammals balance the opposing needs of maintaining an immunological environment conducive to successful pregnancy while attempting to control a dangerous pathogen. Moreover the mouse has proven useful for testing the potential of a number of vaccine candidates and adjuvants for their ability to prevent congenital infection and/or reduce foetal death and abortion.