Decline of Seroprevalence and Incidence of Congenital Toxoplasmosis Despite Changing Prevention Policy—Three Decades of Cord-blood Screening in North-western Switzerland

Abstract

Due to the lack of prospective data, there is an ongoing debate about the need for screening and prevention programs for congenital toxoplasmosis in Europe. Accordingly, individual countries have chosen different public health strategies. A cord-blood screening program for congenital toxoplasmosis was established in 1982 in obstetric units of hospitals in North-Western Switzerland. Samples were tested for specific immunoglobulin G (IgG) and IgM, and after 1992 also for IgA antibodies. Suspicious test results triggered additional investigations to identify children with congenital toxoplasmosis. From 1982 to 2015, 119,166 cord-blood samples have been collected and analyzed for the presence of Toxoplasma-specific antibodies. Although maternal age rose from 28.2 to 32.2 years during this period, a decrease of seroprevalence from 53% to 20% was observed. The incidence of congenital toxoplasmosis decreased by 85% (from 0.08% to 0.012%) and remained low despite abandoning prevalent nonsystematic screening during pregnancy in Switzerland. Our data document a steady decline of both Toxoplasma gondii seroprevalence and congenital toxoplasmosis incidence in Switzerland even after abolition of the nonsystematic prenatal screening a decade ago. The data support abandoning toxoplasmosis screening programs in low-incidence, high-income countries such as Switzerland.