Congenital Toxoplasmosis

Congenital toxoplasmosis: Should we still care about screening?

Prenatal systematic screening for congenital toxoplasmosis has been performed in Austria and France since 1975 and neonatal screening for congenital toxoplasmosis has been part of the New England Newborn screening program since 1986.

In this narrative review we review the data leading up to the systematic screening programs in Austria and France, highlighting the main finding of the European Union funded research in the 1990s and early 2000s. Different descriptive studies of the effect of pre- or postnatal treatment are discussed. Toxoplasma gondii has different genetic lineages with different pathogenicity in humans. This means that results in areas with a low pathogenic lineage cannot be extrapolated to an area with highly pathogenic lineages. The importance of meat as a source of infection is discussed in the light of an increased prevalence of T.gondii in organic livestock production .

Detection by enzyme immunosorbent assay of Toxoplasma gondii IgG antibodies in dried blood spots on PKU-filter paper from newborns

Different ways of eluting IgG antibodies against Toxoplasma gondii from blood spots on PKU filter papers from newborns were examined, and the eluate was analysed by Enzyme Immunosorbent Assay (EIA). 10-mm diameter discs (method A), and 3-mm discs (method B) were eluted overnight, and 3-mm discs were eluted directly for 2 hours in the EIA wells (method C). Two groups of paired samples were tested: blood spots on the PKU card from the newborn, cord blood, and a venous blood sample from the mother collected shortly after delivery (Group 1, 191 samples); or PKU cards from the newborns and serum collected from the mother during the first trimester (Group 2, 426 samples). The best results were found for Group 1; method A, a sensitivity of 100% (63/63), and a specificity of 100% (128/128) (r = 0.934, P < 0.0001), and for Group 2; method C, a sensitivity of 100% (125/125), and a specificity of 100% (301/301) (r = 0.822, P < 0.0001). When method C, was used on 188 samples stored for 16-18 month at -20 degrees C, a sensitivity of 100% (62/62) and a specificity of 99.2% (125/126) (r = 0.913, P < 0.0001) were found. The PKU filter paper method is reliable and reproducible, and can be used in screening projects based on analysis of neonatal samples, and in epidemiological studies on toxoplasmosis in pregnant women.

Prevalence, incidence and geographical distribution of Toxoplasma gondii antibodies in pregnant women in Denmark

The purpose of this study was to determine the prevalence and incidence of toxoplasmosis in pregnant women in Denmark, and to estimate the incidence of congenital toxoplasmosis. Consecutive serum samples from 5,402 women were analysed for specific IgG and IgM Toxoplasma gondii antibodies by EIA. The prevalence of IgG antibodies was 27.4%. The seroconversion rate was estimated to be 1.16% per year (SE = 0.0017) in all age groups, consistent with an incidence of acute toxoplasmosis in pregnant women of 0.65%. Specific IgM antibodies were present in sera from 29 women. Based on an assumed maternofetal transmission rate of 50%, the incidence of congenital toxoplasmosis was estimated to be 0.33%. Based on these data it is predicted that about 410 pregnant women are infected with T. gondii every year in Denmark, and that about 200 children every year are infected in utero by T. gondii. There was no difference in the prevalence of antibodies in women from rural or urban areas, or from different parts of Denmark.