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Published on: December 9, 2014
Association of Parasite Load Levels in Amniotic Fluid With Clinical Outcome in Congenital Toxoplasmosis
Lidia Yamamoto1, Lília S Targa, Laura M Sumita
1Laboratory of Seroepidemiology and Immunobiology and Laboratory of Virology, Institute of Tropical Medicine, and LIM 48-Laboratory of Immunology, Department of Infectious and Parasitic Diseases, School of Medicine, University of São Paulo, São Paulo, Brazil.
Insights
Parasite load in amniotic fluid predicts congenital toxoplasmosis outcomes. Higher parasite levels in amniotic fluid correlate with symptomatic and severe infections in infants.
Area of Science:
- Medical Parasitology
- Maternal-Fetal Medicine
- Neonatology
Background:
- Congenital toxoplasmosis, caused by *Toxoplasma gondii*, poses risks to neonatal and infant health.
- Accurate prediction of clinical outcomes is crucial for timely intervention.
Purpose of the Study:
- To determine the correlation between parasite load in amniotic fluid (AF) and clinical outcomes in infants with congenital toxoplasmosis.
- To assess the influence of gestational age at maternal infection on these outcomes.
Main Methods:
- Retrospective cohort study of 122 children born to mothers with toxoplasmosis during pregnancy.
- Quantitative polymerase chain reaction (qPCR) of stored AF samples to measure parasite load.
- Correlation analysis of AF parasite load, gestational age at infection, and neonatal clinical outcomes up to 12 months.
Main Results:
- Parasite load in AF varied significantly, with higher levels associated with symptomatic and severe infections.
- Gestational age at maternal infection was inversely correlated with parasite load and symptom severity.
- Parasite load was a strong predictor of symptomatic infection (AUC 0.959) and severe outcomes.
Conclusions:
- Amniotic fluid parasite load is a significant independent predictor of clinical outcomes in congenital toxoplasmosis.
- Measuring parasite load in AF can aid in risk stratification and management of affected neonates.
- Early detection and quantification of *Toxoplasma gondii* in AF are vital for predicting infant prognosis.
Objective:
To correlate neonatal and infant clinical outcome with parasite load in amniotic fluid (AF).
Methods:
We conducted a retrospective cohort study of 122 children whose mothers had toxoplasmosis during pregnancy. The children were monitored from birth to 12 months old. Stored AF samples were obtained at maternal diagnosis and tested by quantitative polymerase chain reaction. Gestational age at maternal infection, quantitative polymerase chain reaction results, neonatal anti-Toxoplasma gondii immunoglobulin (Ig) M, and clinical outcome at 12 months were correlated.
Results:
Maternal infection occurred in 18 of 122 (14.7%) and 104 of 122 (85.2%) women in the first and second trimesters, respectively. At birth, IgM was present in 107 of 122 (87.7%) neonates and 36 (29.5%) were symptomatic. Of these, half occurred in the first and the other half in the second trimester and 6 of 36 had severe infections (16.7% of symptomatic, 4.9% of total), all infected in the first trimester. Parasite load levels were highly variable (median 35 parasites/mL, range 2-30,473). Logistic regression correlated symptomatic infection with gestational age (odds ratio [OR] 0.47, CI 0.31-0.73) and parasite load (OR 2.04, CI 1.23-3.37), but not with positive IgM (OR 6.81, CI 0.86-53.9). Negative correlations were found between gestational age and parasite load (rs -0.780, CI -0.843 to -0.696), gestational age and symptoms (rs -0.664, CI -0.755 to -0.547), but not gestational age and IgM (rs -0.136, CI -0.311 to 0.048). Parasite load levels distributed by percentile showed that all symptomatic patients appeared from the 75th percentile and all severe infections from the 95th percentile. Load rankings showed doubled the OR for each 20 parasite/mL increment. Parasite load was associated with symptomatic infections (area under the curve 0.959, CI 0.908-0.987) as well as gestational age (area under the curve 0.918, CI 0.855-0.960) and both parameters combined (area under the curve 0.969, CI 0.920-0.992).
Conclusion:
Parasite load in AF is associated with the clinical outcome in congenital toxoplasmosis, irrespective of gestational age at maternal infection.
