Congenital toxoplasmosis--a report on the Danish neonatal screening programme 1999-2007

This paper reports on the national neonatal screening programme for congenital toxoplasmosis (CT) in Denmark conducted from 1999 to 2007, including background, basis for initiation of screening, methods, results, and finally reasons for the discontinuation of the screening.

A nationwide screening was conducted at Statens Serum Institut, including >98% newborns, and using filter paper eluates (Guthrie card, PKU card) obtained from newborns 5-10 days old. These were analysed for Toxoplasma gondii-specific antibodies (IgM), and if positive, then IgM (ISAGA). Confirmatory serology was performed on children and their mothers (IgM, IgG, IgA, dye test) where infection was suspected, and children with suspected or confirmed CT initiated a 3-month treatment regimen with pyrimethamine, sulfadiazine and folinic acid supplements. Selective cohorts were followed with regard to developmental and clinical outcome.

A total of 100 children were diagnosed with CT in the screening period, and only 2 cases were detected outside of the screening programme. CT prevalence was 1.6 per 10,000 live-born infants. Follow-up studies showed new retinochoroidal lesions in affected children despite treatment.

Screening was terminated August 2007, after it became apparent that no benefit of treatment could be shown. CT was evaluated using a Danish adaptation of the Uniform Screening Panel (ACMG), showing CT as an unlikely candidate for screening today. Whereas results might be comparable with other low-endemic countries with similar strains of T. gondii, neonatal screening and treatment might offer different results in regions with either high prevalence or different strains of T. gondii.