The performance of four molecular methods for the laboratory diagnosis of congenital toxoplasmosis in amniotic fluid samples

HLA-DQA1/B1 alleles as putative susceptibility markers in congenital toxoplasmosis

“…It is known that more recent techniques such as Real Time PCR tend to be more sensitive than conventional PCR, but even these quantitative techniques are not able to rule out the presence of infection 20 i.e., there will be always around 10% of the casuistic that will be infected and present negative serological results at birth. 14,[19][20][21][22][23] A factor that is likely to decrease the sensitivity of PCR is that all of the pregnant women were under treatment at the time of amniocentesis because of the protocol to treat pregnant women that is recommended by the Brazilian Ministry of Health. Due to the treatment administered to women who have seroconverted during pregnancy with either spiramycin, or a combination of sulfadiazine and pyrimethamine, and also to the fact that the newborns of these women also receive, even if in an indirect way, the drug through the placenta, it is common that fetuses are asymptomatic at birth and during the first months of life and also have undetectable IgM antibodies accompanied by IgG levels that are similar to the maternal ones or even lower, especially if the mothers began the treatment early in pregnancy, and received it for prolonged periods.…”

“…These two infants presented with the Sabin's triad of symptoms (hydrocephalus, cerebral calcifications and chorioretinitis) and high parasite loads determined by Real Time PCR 14 in amniotic fluid samples (10 3 and 10 4 parasites/ml) despite the mothers' treatment. These two fetuses carried susceptibility alleles, one of them was heterozygous for HLA-DQA1 Table 2, but as we decided to accept as statistically significant only results with pc-values < 0.005, this allele was not highlighted in the present study, nevertheless should be re-analyzed in replication studies.…”

“…The second parameter that was required to meet the inclusion criteria of the present study was a positive detection of T. gondii DNA in amniotic fluid samples by conventional nested PCR and also by a Real Time PCR according to previously described protocols. 13,14 Finally, a case of congenital toxoplasmosis must have been confirmed at birth or at some point during the follow-up of the infants, which were performed until the age of 12 months, coinciding with the end of the toxoplasmosis treatment in infants. The confirmation of the newborn/infant diagnosis was based on the presence of anti-T. gondii IgM antibodies and/or high IgG titers (significantly higher than the maternal titers).…”

Infección por toxoplasma

“…Cabe resaltar que el resultado que se obtiene de una infección en una mujer embarazada y de la infección congénita del bebé es potenciado por la poca madurez del sistema inmune del feto, lo cual le impide actuar en su defensa propia contra un agente parasitario como este. Normalmente, el bebé nace con una toxoplasmosis congénita benigna, con riesgo de una reactivación de quistes toxoplásmicos, y de que estos generen afecciones, especialmente en la retina [36,37].…”

“…Demostración directa del parásito indirecta (IFAT), hemaglutinación indirecta (IHA) y el método más conveniente: ensayo por inmunoabsorción ligado a enzimas (ELISA) [44,37].…”