Control of congenital infection with Toxoplasma gondii by neonatal screening based on detection of specific immunoglobulin M antibodies eluted from phenylketonuria filter-paper blood-spot samples.

Two ongoing neonatal screening programmes for congenital infection with Toxoplasma gondii are presented. The New England Newborn Screening Programme has included congenital toxoplasmosis since 1986. The test is based on detection of Toxoplasma-specific immunoglobulin M (IgM) antibodies eluted from the phenylketonuria (PKU) card. The seroprevalence of Toxoplasma IgG antibodies is at present about 13% and the birth prevalence of congenital toxoplasmosis approximately 1 per 10000 liveborn children. The Danish national neonatal screening programme was expanded to include congenital toxoplasmosis from 1 January 1999. The test is also based on detection of Toxoplasma-specific IgM antibodies eluted from PKU cards. The seroprevalence of Toxoplasma IgG antibodies in pregnant women is around 25% and the birth prevalence about 1 per 3000 liveborn children. The birth prevalence of congenital Toxoplasma infection is within the range of other congenital disorders included in different screening programmes. Neonatal screening is feasible in areas with a low risk of congenital infection where prenatal screening will not be applicable.