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Aims: To develop a population pharmacokinetic model for pyrimethamine (PYR) and sulfadoxine (SDX) in children with congenital toxoplasmosis., Methods: Children were treated with PYR (1.25 mg kg(-1)) and SDX (25 mg kg(-1)) (Fansidar) plus folinic acid (Lederfoline) 5 mg). Plasma concentrations, available from a therapeutic drug monitoring database, were determined by high-performance liquid chromatography. Population pharmacokinetic analysis was performed using a nonlinear mixed effects model., Results: Eighty-nine children, aged 1 week to 14 years and weighing 2.9-59 kg, were available for evaluation. Both PYR and SDX concentration-time profiles were best described by a one-compartment open model. Volume of plasma distribution (V) and clearance (CL) were significantly related to body weight (BW) using an allometric function. Typical CL and V estimates (95% confidence interval), for a child weighing 11 kg were 5.50 (5.28, 5.73) l day(-1) and 36 (33, 39) l for PYR and 0.26 (0.25, 0.27) l day(-1) and 2.1 (1.9, 2.3) l for SDX. For BW between 3.5 and 60 kg, plasma half-lives were predicted to vary from 4.0 to 5.2 days for PYR, and from 5.0 to 7.5 days for SDX., Conclusion: This study indicated that body weight influences PYR and SDX pharmacokinetics in children. To optimize PYR/SDX combination treatment in congenital toxoplasmosis, short dosing intervals in very young low-wight children are probably appropriate.

We describe two unusual cases of congenital toxoplasmosis, one occurring after preconception maternal infection with cervical adenopathies and the other occurring after maternal infection at the very end of pregnancy with maternal seronegativity at delivery. These documented cases of congenital toxoplasmosis demonstrate the value of extending the serologic monitoring period during pregnancy, according to the individual clinical context.

We report a rare case of congenital toxoplasmosis transmitted by an immunocompetent woman infected before conception. Active toxoplasmosis was suspected due to persistent lymphadenitis with specific IgM, IgA, IgE antibodies. Prenatal diagnosis based on amniocentesis and fetal blood sampling at 24 weeks' amenorrhoea was positive on amniotic fluid, and fetal infection was confirmed after termination. In our opinion such cases need the same monitoring as when seroconversion occurs during the first trimester. A pregnancy-free interval of six to nine months is recommended after proven patent toxoplasmosis seroconversion.

Unlabelled: The purpose of this study was to determine the clinical and immunological outcome of 78 children with congenital toxoplasmosis treated with the pyrimethamine-sulfadoxine combination between 1980 and 1997., Methods: Children were divided into 3 groups according to the initial duration of treatment (always including folinic acid, 5 mg/week by mouth), as follows: pyrimethamine (1.25 mg/kg every 15 d) + sulfadoxine (25 mg/kg every 15 d) for 12 months (Group 1, 47 children), or for 24 months, with or without prenatal therapy (respectively, Group 2, 19 children, and Group 3, 12 children)., Results: Chorioretinitis occurred in 23% of these 78 children. Four children had unilateral blindness, 1 had mild epileptic fits and 1 had psychomotor retardation. The lowest rate of sequelae were in Groups 2 and 3. Immunological rebounds, generally without clinical repercussions, occurred frequently (90% of cases on average) during, or more often after therapy, regardless of the treatment duration. Treatment was always well tolerated., Conclusions: Our current treatment strategy for congenital toxoplasmosis consists of a 24-month course of pyrimethamine-sulfadoxine (Fansidar) combined with folinic acid (Lederfoline). If the prenatal diagnosis is positive, we also prescribe this treatment to the mother until delivery. This combination offers satisfactory compliance, adequate serum concentrations, and good preventive efficacy.

Two hundred and sixty-one pregnant women underwent prenatal screening by cordocentesis and/or amniocentesis between 1987 and 1994. The following tests were used: (i) detection of anti-Toxoplasma gondii IgM, IgA, and IgE antibodies by immunocapture and the comparative immunological profile method based on enzyme-linked immunofiltration assay of fetal blood and (ii) direct detection of the parasite in cell culture and by mouse inoculation with fetal blood (FB) and/or amniotic fluid (AF). Of the 31 cases of congenital toxoplasmosis, 24 (77 per cent) were detected prenatally. Overall, the FB and AF inoculation methods were the most effective (50 per cent sensitivity with FB inoculation to mice and/or cell culture and 74 per cent with AF). However, antibody detection in FB was the only positive test in three cases. Of 18 surviving children diagnosed prenatally, only one developed chorioretinitis (9 months of age). Seven newborns (23 per cent) with negative prenatal tests were diagnosed by postnatal laboratory monitoring, but none of these children developed clinical toxoplasmosis. There may have been more false negatives, as only 48 per cent of unaffected children were followed up for at least 12 months. All the tests had a specificity of 100 per cent. Fetal blood sampling has considerable value but also carries some risks and is currently being abandoned in favour of amniocentesis alone with gene amplification and mouse inoculation.

Objective: To emphasize the importance of follow-up after birth of infants with an antenatal diagnosis of congenital toxoplasmosis., Methods: Retrospective study from July 1987 through January 31 1995 on 211 women (214 fetuses) who had undergone ovular biopsy for toxoplasmosis seroconversion during pregnancy., Results: Antenatal diagnosis was positive in 13 patients (6.2%). Four pregnancies were terminated during the second trimester. Delivery was triggered at 37 weeks gestation in one woman and in 8 others pregnancy was continued with Fansidar. All infants were born live with infraclinic disease. Two fetal deaths related to biopsy technique occurred (0.95%) and one pregnancy was terminated before the results had been obtained. Only 21.3% of the patients were delivered in our unit. A total of 197 infants were delivered with a negative antenatal diagnosis: 93 were healthy, 5 had congenital toxoplasmosis, 1 died at 3 months and 98 had no or incomplete follow-up., Conclusion: Incomplete post-natal follow-up is in contradiction with the excellent performance of antenatal diagnosis of congenital toxoplasmosis. Greater care is needed, especially since now only an amniocentisis is required to detect the parasite genome with polymerase chain reaction.

Diagnostic strategies for congenital toxoplasmosis have changed profoundly in recent years. Immunological diagnostic methods, long considered disappointing, can now be used at a very early stage. Over a 3-year period, 1,050 infants at risk of congenital toxoplasmosis (born to 1,048 mothers infected during pregnancy) were monitored for a minimum of 12 months and a maximum of 7 years. More than 6,000 serum specimens were analyzed by comparative mother-infant immunological profiles (CIPs) based on an enzyme-linked immunofiltration assay (ELIFA) and an immunocapture method for the detection of specific immunoglobulin M (IgM) and IgA. IgG antibodies were also titrated. One hundred three cases of congenital toxoplasmosis were demonstrated. The CIP-ELIFA method had a better diagnostic yield (sensitivity, 90%) than specific IgM and/or IgA detection by immunocapture assay (sensitivity, 77%). By using a combination of these tests, congenital infection was diagnosed in the first month and the first 3 months of life in 90 and 94% of infants with toxoplasmosis, respectively, with a specificity of 99.8% and a positive predictive value of 99% at 8 months of age. This dual diagnostic approach (ELIFA and IgM-IgA immunocapture) is highly efficient and has important implications for therapy. Indeed, early postnatal diagnosis based on objective evidence enables therapy with pyrimethamine-sulfadoxine to be started immediately for 24 months, while spiramycin (which used to be given preventively for 9 to 12 months to all infants at risk) can be stopped after the first 3 months of life.

The authors report 2 cases of congenital toxoplasmosis fortuitously diagnosed in 2 newborn infants aged 12 and 35 days respectively whose mothers had no anti-Toxoplasma antibodies detectable at the time of birth. These cases prompted us to carry out, over an 18 months' period, a systematic postnatal control of all pregnant women who were still seronegative at the time of delivery. This enabled us to detect 4 cases of perinatal maternal infection with Toxoplasma contamination in 2 neonates. In view of these results, and in order not to miss any maternal infection at the very end of pregnancy, it seems advisable to complete the control of seronegative women by taking a last blood sample about 30 days after they have given birth.

More than 8000 samples (sera, cord blood, CSF, etc.) from patients who had, or were likely to have, toxoplasmosis were studied by the CIP-ELIFA technique. The first stage in this technique is immunoelectrodiffusion on a microporous cellulose acetate membrane. In the second stage, immunodetection and isotypic characterization of the precipitating systems are rapidly carried out by immunofiltration with anti-IgG, IgM, IgA or IgE-labelled antibodies (enzyme-linked immunofiltration assay or ELIFA). Several samples are jointly laid out on the same membrane for compared immunological profiles (CIP). When applied to the mother-foetus relationship in toxoplasmosis, this procedure provides an early diagnosis of congenital infestation in 85% of the cases. Positive criteria are based on evidence of specific IgM, IgE or IgA in the child, but also on the detection of foetal or neonatal antitoxoplasmosis IgG which can be distinguished from the IgG transmitted by the mother. Polyisotypic supervision is of considerable value for assessment of prognosis and of therapeutic effectiveness at the end of treatment. Satisfactory isotypic characterization can only be achieved by using particular functional antigens.