Mead et al. (27) have estimated that approximately 225,000 new cases are reported each year in the United States and assume that 50% of the cases are due to food-borne transmission of T. gondii. The National Hospital Discharge survey indicated that toxoplasmosis was the first diagnosis for approximately 5,000 discharges each year between 1992 and 1996, including 750 deceased patients. Furthermore, 4,000 persons with AIDS will develop toxoplasmic encephalitis in the United States each year (27).