Diagnosis, treatment, and prevention of congenital toxoplasmosis in the United States

Congenital toxoplasmosis (CT) is a parasitic disease that can cause significant fetal and neonatal harm. Coordinated efforts by pregnant women, researchers, physicians, and health policy makers regarding potential primary and secondary preventive measures for CT and their implementation may lead to a lower incidence of CT as well as lower morbidity and mortality rates associated with CT. In the United States, the age-adjusted seroprevalence of Toxoplasma gondii among women of childbearing age (15-44 years) has declined over time (15%, 11%, and 9% in 1988-1994, 1999-2004, and 2009-2010, respectively; among US-born women only, the seroprevalence rates during these time periods were 13%, 8%, and 6%, respectively). Thus, approximately 91% of women of childbearing age in the United States are susceptible to Toxoplasma infection. Should these women become infected during pregnancy and remain undiagnosed and untreated, they could deliver an infant with CT. However, the incidence of acute primary infection is likely very low in the current era and is probably much lower than the 1.1 in 1000 pregnant women originally reported in 1960s. There are 3 ways CT can occur. First, CT can develop through transmission of T gondii to the fetus from a previously seronegative, immunocompetent mother who acquired acute primary infection during pregnancy or within 3 months before conception. Second, CT can occur through reactivation of toxoplasmosis in a previously T gondii-immune pregnant woman who was severely immunocompromised during pregnancy. Third, CT can result after reinfection of a previously immune pregnant mother with a new, more virulent strain (eg, after international travel or after eating undercooked meat from areas where more virulent atypical strains predominate).