Novel paradigm enables accurate monthly gestational screening to prevent congenital toxoplasmosis and more

Background

Congenital toxoplasmosis is a treatable, preventable disease, but untreated causes death, prematurity, loss of sight, cognition and motor function, and substantial costs worldwide.

Methods/Findings

In our ongoing USA feasibility/efficacy clinical trial, data collated with other ongoing and earlier published results proved high performance of an Immunochromatographic-test(ICT) that enables accurate, rapid diagnosis/treatment, establishing new paradigms for care. Overall results from patient blood and/or serum samples tested with ICT compared with gold-standard-predicate-test results found ICT performance for 4606 sera/1876 blood, 99.3%/97.5% sensitive and 98.9%/99.7% specific. However, in the clinical trial the FDA-cleared-predicate test initially caused practical, costly problems due to false-positive-IgM results. For 58 persons, 3/43 seronegative and 2/15 chronically infected persons had false positive IgM predicate tests. This caused substantial anxiety, concerns, and required costly, delayed confirmation in reference centers. Absence of false positive ICT results contributes to solutions: Lyon and Paris France and USA Reference laboratories frequently receive sera with erroneously positive local laboratory IgM results impeding patient care. Therefore, thirty-two such sera referred to Lyon's Reference laboratory were ICT-tested. We collated these with other earlier/ongoing results: 132 of 137 USA or French persons had false positive local laboratory IgM results identified correctly as negative by ICT. Five false positive ICT results in Tunisia and Marseille, France, emphasize need to confirm positive ICT results with Sabin-Feldman-Dye-test or western blot. Separate studies demonstrated high performance in detecting acute infections, meeting FDA, CLIA, WHO ASSURED, CEMark criteria and patient and physician satisfaction with monthly-gestational-ICT-screening.

Conclusions/Significance

This novel paradigm using ICT identifies likely false positives or raises suspicion that a result is truly positive, rapidly needing prompt follow up and treatment. Thus, ICT enables well-accepted gestational screening programs that facilitate rapid treatment saving lives, sight, cognition and motor function. This reduces anxiety, delays, work, and cost at point-of-care and clinical laboratories.

Author’s Summary

Toxoplasmosis is a major health burden for developed and developing countries, causing damage to eyes and brain, loss of life and substantial societal costs. Prompt diagnosis in gestational screening programs enables treatment, thereby relieving suffering, and leading to > 14-fold cost savings for care. Herein, we demonstrate that using an ICT that meets WHO ASSURED-criteria identifying persons with/without antibody to Toxoplasma gondii in sera and whole blood with high sensitivity and specificity, is feasible to use in USA clinical practice. We find this new approach can help to obviate the problem of detection of false positive anti- T.gondii IgM results for those without IgG antibodies to T.gondii when this occurs in present, standard of care, predicate USA FDA cleared available assays. Thus, this accurate test facilitates gestational screening programs and a global initiative to diagnose and thereby prevent and treat T.gondii infection. This minimizes likelihood of false positives (IgG and/or IgM) while maintaining maximum sensitivity. When isolated IgM antibodies are detected, it is necessary to confirm and when indicated continue follow up testing in ∼2 weeks to establish seroconversion. Presence of a positive ICT makes it likely that IgM is truly positive and a negative ICT makes it likely that IgM will be a false positive without infection. These results create a new, enthusiastically-accepted, precise paradigm for rapid diagnosis and validation of results with a second-line test. This helps eliminate alarm and anxiety about false-positive results, while expediting needed treatment for true positive results and providing back up distinguishing false positive tests.

Concerning one case of rupture of a flow regulator: How patient safety procedures contribute to the correct use of medical devices

Flow regulators are widely used in hospitals to assist with intravenous (IV) infusion of medication. The rupture of a flow regulator at the base of the clamp was observed during parenteral nutrition. This rupture resulted in fluid leakage and an inlet of air, responsible for an air embolism in a fragile patient who had undergone a bilateral lung transplant. The patient's clinical condition required him to be transferred to a continuous monitoring unit. A serious Adverse Event in Healthcare (AEH) was reported, as well as a medical device vigilance report. A Feedback Committee (FC) was set up and it recommended an audit within the health care departments to study the conditions for use of flow regulators and to propose corrective actions. Despite the technical data sheet of the device not recommending the administration of lipid emulsions and glucose solutions above 10%, the manufacturer's expert report concluded that the mechanical failure could not be linked to the type of solution. However, the audit did reveal a lack of knowledge of certain rules for using this device. The analysis of this AEH is part of the establishment's patient safety procedure. The AEH highlighted a deviation in care concerning the conditions for use of flow regulators, thus resulting in misuse. The collaboration between the various actors involved in the analysis of this AEH led to the implementation of improvement actions on the root causes, related to the lack of information and of training for professionals on correct use of the medical device.

[Toxoplasmosis in pregnancy: Practical Management]

The burden of congenital toxoplasmosis has become small in France today, in particular as a result of timely therapy for pregnant women, fetuses and newborns. Thus, the French screening and prevention program has been evaluated and recently confirmed despite a decline over time in the incidence of toxoplasmosis. Serological diagnosis of maternal seroconversion is usually simple but can be difficult when the first trimester test shows the presence of IgM, requiring referral to an expert laboratory. Woman with confirmed seroconversion should be referred quickly to an expert center, which will decide with her on treatment and antenatal diagnosis. Although the level of proof is moderate, there is a body of evidence in favor of active prophylactic prenatal treatment started as early as possible (ideally within 3 weeks of seroconversion) to reduce the risk of maternal-fetal transmission, as well as symptoms in children. The recommended therapies to prevent maternal-fetal transmission are: (1) spiramycin in case of maternal infection before 14 gestational weeks; (2) pyrimethamine and sulfadiazine (P-S) with folinic acid in case of maternal infection at 14 WG or more. Amniocentesis is recommended to guide prenatal and neonatal care. If fetal infection is diagnosed by PCR on amniotic fluid, therapy with P-S should be initiated as early as possible or continued in order reduce the risk of damage to the brain or eyes. Further research is required to validate new approaches to preventing congenital toxoplasmosis.

[Motivations for a consultation before adoption: A multicenter study]

INTRODUCTION

While the number of international adoptions in France is decreasing, adopted children are older and in poorer health than they used to be. This phenomenon has resulted in an increase in the demand for preadoption consultations over the past several years. This study analyses the reasons for these consultations.

METHOD

Prospective multicenter study conducted from 1 January to 31 December 2013.

RESULTS

Ten centers contributed to the study, i.e., 196 preadoption consultations. Seeking medical advice was the reason for 88% of the consultations, whether the advice was based on the study of an identified child's medical file (32%) or a country's healthcare characteristics, whether the country was identified (34%) or not (23%). In 6% of cases, the motive for preadoption consultations was social and familial, and in the last 5% it was to obtain general information about adoption and its procedures. In more than 40% of the cases, whether the child or the country identified, Russia is the subject of the consultation because of the complexity of the files and because of the dreaded but rarely mentioned fetal alcohol syndrome.

CONCLUSION

The deterioration of adopted children's health is an additional worry for future adoption applicants. To provide them with the best information possible without making choices for them, specialists should have substantial experience in adoption before going into these preadoption consultations.

Seasonal variations in acute toxoplasmosis in pregnant women in the Rhône-Alpes region (France)

To search for seasonal variations we analysed data on 1998 acute toxoplasmic infections diagnosed between 1988 and 2009 in pregnant women. Two distinctive transmission profiles were observed: one in rural areas, which was strongly influenced by seasons with significantly fewer infections in the first half of the year but maximal risks at the end of summer and end of autumn, and a stable urban distribution with only moderate peaks. Further studies on individual risks and environmental and climatic factors are needed to understand what prevention message should be given to susceptible pregnant women.

When are we going to celebrate the centenary of the discovery of efficient treatment for congenital toxoplasmosis?

In 2008, we have celebrated the centenary of the discovery of Toxoplasma gondii.Although this ubiquitous protozoan can generate devastating damage in foetuses and newborns, its treatment is the only field in which we have made little progress, despite a huge body of research, and has not yet been validated. Pregnant women who seroconvert are generally given spiramycine in order to reduce the risk of vertical transmission. However, to date, we have no evidence of the efficacy of this treatment because no randomized controlled trials have as yet been conducted. When foetal contamination is demonstrated, pyrimethamine, in association with sulfadoxine or sulfadiazine, is normally prescribed, but the effectiveness of this treatment remains to be shown. With regard to postnatal treatment, opinions vary considerably in terms of drugs, regimens and length of therapy. Similarly, we do not have clear evidence to support routine antibiotic treatment of acute ocular toxoplasmosis. We must be aware that pregnant women and newborns are currently being given empirically potentially toxic drugs that have no proven benefit. We must make progress in this field through well-designed collaborative studies and by drawing the attention of policy makers to this disastrous and unsustainable situation.

Factors affecting the adherence to an antenatal screening programme: an experience with toxoplasmosis screening in France

Monthly serological testing is mandatory in France for pregnant women not immune to toxoplasmosis. We assessed for the first time the adherence to this national programme, using data from antenatal tests for Toxoplasma antibodies collected by the Union of Health Insurance Services in the French Rhone-Alpes region.

Factors affecting the adherence to an antenatal screening programme: an experience with toxoplasmosis screening in France

Monthly serological testing is mandatory in France for pregnant women not immune to toxoplasmosis. We assessed for the first time the adherence to this national programme, using data from antenatal tests for Toxoplasma antibodies collected by the Union of Health Insurance Services in the French Rhone-Alpes region. Data from 34,290 pregnancies was analysed. The first test was done late in 25% of women (8,430). Women had on average 5.7 tests during pregnancy, only 40 percent (13,774) were tested seven or more times as recommended. Young women were more likely to have a late first test, but age did not significantly influence regularity and number of tests. Free medical coverage favoured a late first test, fewer tests and longer between-test intervals. An early first test did not affect test numbers or between-test intervals. A re-useable prescription for several tests was associated with better adherence. Prescription by general practitioners was associated with an earlier first test, but fewer tests and longer between-test intervals. When prescribing physician(s) included a gynaecologist, the first test was more likely to be behind schedule, but the overall number of tests was higher and between-test intervals shorter. Because data was collected through private laboratories, our conclusions apply to the majority of French patients who need to schedule a separate visit for blood testing after prescription.

Impact of spiramycin treatment and gestational age on maturation of Toxoplasma gondii immunoglobulin G avidity in pregnant women

The objective of the present study was to investigate the maturation of immunoglobulin G (IgG) avidity after Toxoplasma gondii seroconversion during pregnancy and the factors that affect IgG avidity over time. The study used 309 serum samples from 117 women and a multiple linear mixed regression analysis to show the patterns of variation of IgG avidity throughout gestation. The IgG avidity ratios and the patterns of their evolution with time were quite diverse among the women and were statistically heterogeneous (P = 0.011); however, the trend was toward a statistically significant increase (P < 0.0001). On average, a 1.0167-fold increase was observed for each additional gestational week after the putative date of infection. At 12 weeks after putative infection (the expected IgG avidity maturation time), the mean avidity ratio was 16.6% (95% confidence interval, 15.4 to 17.9%). At all times, the avidity ratio remained significantly heterogeneous among the women (P < 0.05); for 95% of them, that ratio ranged from 7.8 to 35.3% at 12 weeks after putative infection. Maternal age at the putative time of infection did not influence the maturation of IgG avidity. However, on average, a 1.009-fold decrease (P = 0.03) in that avidity was observed for each additional week of gestational age before infection and a 1.03-fold increase (P = 0.0003) was observed for each additional week of delay to the onset of spiramycin treatment. The rate of increase in the avidity ratio was lower if infection occurred late in pregnancy and higher if the delay to treatment was long. This information cannot allow accurate determination of the delay since the time of infection. The present results provide support for interpretation of the assay and caution against overinterpretation.

Toxoplasma gondii: Comparison of human CD34+ and monocyte-derived dendritic cells after parasite infection

Human dendritic cells (DC) obtained in vitro from CD34(+) progenitors (CD34-DC) or blood monocytes (mo-DC) are different DC which may be used in a model of T. gondii infection. We compared the survival, infection rate and cell surface receptor expression of both DC types after living T. gondii tachyzoite infection. CD34-DC appeared less resistant to the parasite than mo-DC. At 48h post-infection, chemokine receptors responsible for DC homing and migration were absent in mo-DC, while down regulation of CCR6 and up regulation of CCR7 was observed in CD34-DC. This result, suggesting migration ability of CD34-DC, was confirmed by in vitro migration experiments against different chemokines. Tachyzoite supernatant, used as chemokine, attracted immature CD34-DC as observed by MIP3alpha, while MIP3beta, as expected, attracted mature CD34-DC. Under similar conditions, no significant difference was noticed between mature or immature mo-DC. These data indicated that CD34-DC represent an alternative model that allows migration assay of infected DC by T. gondii.

Delayed maturation of immunoglobulin G avidity: implication for the diagnosis of toxoplasmosis in pregnant women

The low avidity of immunoglobulin G has been reported to be a useful marker of recent infection with Toxoplasma. Several investigators, however, have published discrepant result on the maturation of avidity over time. The aim of this study was to analyse persistent low avidity of immunoglobulin G in immunocompetent individuals and in pregnant women and how it could interfere in the flowchart of antenatal diagnosis of toxoplasmosis in the latter group. An international literature search was conducted together with a retrospective study of a hospital database. Eleven publications that met the inclusion criteria reported delayed maturation of avidity at a frequency ranging from 0 to 66.6% of the patients. Examination of those publications demonstrated an important heterogeneity in the type of assay used, the calculation of avidity, the cutoff above which avidity was considered to be elevated, and the delay since infection after which indices are expected to be high. In the hospital database, persistent low avidity was found even after a median follow-up period of 6 years. Different factors could interfere with maturation of avidity, such as variations between individuals, the assay system used, and, possibly, the treatment administered. The results of this study clearly demonstrate that, in a pregnant woman, an acute infection cannot be reliably diagnosed solely on the basis of low avidity of immunoglobulin G. Further investigations and standardization of assays are urgently needed. Estimation of the time of infection remains difficult, especially in cases in which the samples are drawn late in pregnancy; the final estimate must be based on several tests repeated at intervals of weeks.

[Congenital ocular toxoplasmosis--ocular manifestations and prognosis after early diagnosis of infection]

BACKGROUND

Congenital toxoplasmosis (CT) is the most frequently encountered congenital infection. The aim of the present review is to report about the long-term outcome of functional and morphological manifestations after an early confirmation of the diagnosis.

PATIENTS AND METHODS

We report on a cohort of patients with serologically confirmed CT, born between 1988 and 2001, who were followed up prospectively at a single centre (Institute of Parasitology, Hôpital de la Croix Rousse, University of Lyon). All patients underwent regular ophthalmological, parasitological and paediatric controls on a half-yearly or annual basis. Ocular manifestations were documented and visual acuity was assessed as far as was possible.

RESULTS

1,506 seroconversions were diagnosed during pregnancy, and 327 of the live-born offspring were seropositive for CT. At the end of the study period, ocular manifestations occurred in 79 of the children (24 %), and in 7 cases (9 %) they were discovered during the first month of life. In 72 of the patients (91 %), the ocular manifestations developed between 1 and 151 months (median follow-up time: 6.3 +/- 3.7 years; range: 0.5 - 14 years) under medical treatment for the first year of life. At the end of the study period, information regarding visual acuity was available for 66 patients. In 55 of these (83 %), visual acuity was normal in both eyes, and in 11 (17 %), it was reduced below 0.5. In 1 child, both eyes were functionally affected, one severely.

CONCLUSION

CT may not become manifest ocularly until after a decade, which underlines the necessity for long-term ophthalmological monitoring of the infected individuals. In our patients, the prognostic outcome after therapy for the first year of life was better than that reported in the literature. This favourable outcome may serve as a basis for patient counselling.

Toxoplasma gondii regulates recruitment and migration of human dendritic cells via different soluble secreted factors

We investigated in vitro the properties of soluble factors produced by Toxoplasma gondii on the recruitment, maturation and migration of human dendritic cells (DC) derived from CD34+ progenitor cells. We used soluble factors including excreted secreted antigens (ESA) produced under various conditions by the virulent type I RH strain (ESA-RH) and the less virulent PRU type II strain (ESA-PRU). Soluble factors of both T. gondii strains appeared to possess a chemokine-like activity that attracted immature DC. This recruitment activity required the presence of functional CCR5 molecules on the cell membrane. Incubation of DC for 24 h with ESA triggered the migration of a large percentage of these cells towards the chemokine MIP-3beta; ESA-PRU was more efficient than ESA-RH. ESA produced in absence of exogenous protein and crude extract did not induce DC migration but retained recruitment activity. These data indicate that recruitment activity and migration-inducing activity are not governed by the same factors. Moreover, incubation of DC for 48 h with ESA did not modify the expression of costimulation or maturation markers (CD83, CD40, CD80, CD86 or HLA-DR), but induced a decrease in CCR6 expression associated with an increased expression of CCR7. Taken together, these results suggest that T. gondii controls recruitment and migration of immature DC by different soluble factors and may induce a dysfunction in the host-specific immune response.

Absence of nucleotide polymorphism in a Plasmodium vivax multidrug resistance gene after failure of mefloquine prophylaxis in French Guyana

Vivax malaria is widespread and resistance has been described for chloroquine and sulfadoxine-pyrimethamine. We report on evidence of failure of mefloquine prophylaxis in a French soldier who contracted Plasmodium vivax in French Guyana, South America. Despite regular weekly mefloquine prophylaxis (250 mg/d), the patient presented with a first episode of vivax malaria, which was treated by chloroquine alone, then experienced a second crisis in France. The reappearance of the parasites occurred one day after the end of prophylaxis, confirming parasitological and clinical resistance in a non-immune patient. Mefloquine was detected by a liquid chromatography assay in plasma at a level of 1062 ng/ml, which was higher than the expected concentration after five months of weekly prophylaxis. This isolate had no single nucleotide polymorphisms of the pvmdr1 gene at seven allele positions: pvmdr1 N91, Y189, Y976, S1071, F1076, N1079 and D1291, corresponding to codons 86, 184, 939, 1034, 1039, 1042 and 1246 in P. falciparum. This observation of failure of mefloquine prophylaxis against P. vivax, when added to previously reported chloroquine and atovaquone-proguanil failure, strengthens the case for re-evaluating drug policies for vivax malaria and the need for continuous research on molecular markers of drug resistance.

Comparative diagnostic performance of two commercial rapid tests for malaria in a non-endemic area

In the study reported here, the diagnostic performance of two new rapid tests for the diagnosis of malaria was evaluated in symptomatic patients in a non-endemic area. Of 557 consecutive patients, 109 (19.6%) had documented malaria. For the NOW ICT MALARIA P.f./P.v. (Binax, Portland, ME, USA) and OptiMAL IT (Diamed, Cressier, Switzerland) tests, respectively, sensitivity values were 96.3% and 79.8% (P-value, 0.0001), and specificity values were 98.8% and 98.4%. The NOW ICT test did not detect two of 80 Plasmodium falciparum infections, and it generated false-positive results for five patients. The OptiMAL IT test failed to detect ten of the P. falciparum infections, and it generated seven false-positive results. The results suggest that these rapid diagnostic tests for malaria may be useful, but they cannot replace microscopic examination of blood films.

Heterogeneity in cellular and humoral immune responses against Toxoplasma gondii antigen in humans

Protection against Toxoplasma gondii in infected patients is mainly attributed to cellular immunity. We here attempt to improve the characterization of the proteins that induce cellular immunity in naturally infected patients. Cellular immunity was evaluated by flow cytometry after 7 days of blood culture from 31 chronically T. gondii infected and 8 noninfected pregnant women, in the presence of soluble T. gondii antigen (ST-Ag) or fractionated proteins from ST-Ag, separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Blood cultures from infected patients with ST-Ag induced 39.5 +/- 12.7% of activated (CD25+) CD4+ T cells using flow cytometry. This contrasts with the absence of activated CD4+ T cells after either culture with PBS or in blood cultures from noninfected women. The protein fraction between 21 and 41.9 kD induced the highest response (14.7 +/- 10.0%). Blood samples from 20 infected and 5 uninfected women were cultured in presence of 12 protein subfractions of 2-208 kD. The highest frequencies of response among infected patients were seen with fractions (Fr) 26-31.9 kD (C.I. 85-100%) and Fr 32-36.9 kD (C.I. 77-100%). Although we note a good concordance between cellular and humoral response, Western blot analysis of ST-Ag does not completely predict the panel of proteins recognized by cellular immunity. Two-dimensional separation of the ST-Ag revealed more than 200 protein spots in these fractions. However, only two proteins in the 20-40 kD range induced a significant humoral response. Further studies are necessary to determine which proteins in the Fr 26-31.9 kD and 32-36.9 kD are superior immunogens for cellular responses.

Duration of the IgM response in women acquiring Toxoplasma gondii during pregnancy: implications for clinical practice and cross-sectional incidence studies

We followed up a cohort of 446 toxoplasma-infected pregnant women to determine the median and variability of the duration of positive toxoplasma-IgM (immunoglobulin M) results measured by an immunofluorescence test (IFT) and an immunosorbent agglutination assay (ISAGA). IgM antibodies were detected for longer using the ISAGA test [median 12.8 months, interquartile range (IQR) 6.9-24.9] than the IFT (median 10.4, IQR 7.1-14.4), but the variability between individuals in the duration of IgM positivity was greatest for the ISAGA test. IgM-positive results persisted beyond 2 years in a substantial minority of women (27.1% ISAGA, 9.1% IFT). Variation in the duration of the IgM response measured by ISAGA and IFT limit their usefulness for predicting the timing of infection in pregnant women. However, measurement of IgM and IgG antibodies in a cross-sectional serosurvey offers an efficient method for estimating the incidence of toxoplasma infection.

Prognostic factors for the long-term development of ocular lesions in 327 children with congenital toxoplasmosis

The aim of this study was to identify the high-risk factors associated with the development of ocular lesions in a large cohort of children with congenital toxoplasmosis (CT), irrespective of their gestational age at the time of maternal infection. Children were managed according to a standardized protocol and monitored for up to 14 years at the Croix-Rousse Hospital, Lyon, France. Cox model and a flexible regression, spline-based method were used for the analysis. During a median follow-up time of 6 years, 79 of the 327 children (24%) had at least one retinochoroidal lesion. No bilateral impairment of visual acuity was observed. The risk of a child developing ocular disease was higher not only when mothers were infected early during pregnancy, which was expected, but also when CT was diagnosed prior to or at the time of birth, when non-ocular manifestations were present at baseline and when birth was premature.

[Real-time PCR for detection of molecular markers of resistance in Plasmodium falciparum]

Plasmodium falciparum drug resistance is a major problem in malaria endemic areas. Molecular markers and in vitro tests have been developed to study and monitor drug resistance. However, none used alone, can provide sufficient data concerning the level of drug resistance and to issue precise guideline for drug use policies in endemic areas. We propose real-time PCR for the simultaneous detection of pfcrt and pfmdr1 genes mutations. The aim of this study was not to provide definitive data concerning the rate of mutations in an endemic area, but to describe a powerful method allowing the detection of major pfmdr1 and pfcrt mutations.

Cellular immunity to Toxoplasma gondii in congenitally infected newborns and immunocompetent infected hosts

The aim of this study was to determine the frequency of anergy to Toxoplasma gondii in congenitally infected newborns and immunocompetent infected individuals. Specific anergy to Toxoplasma has been reported previously, especially in cases of congenital toxoplasmosis. Whole blood from 592 immunocompetent patients with suspected toxoplasmosis was cultured in the presence of soluble Toxoplasma antigen for 7 days. Activated T lymphocytes were detected by flow cytometry. In patients over 1 year of age, the percentage of soluble Toxoplasma antigen-stimulated T cells expressing the interleukin-2 receptor CD25 was higher in infected patients than in uninfected subjects (40.0+/-18.3% vs. 1.8+/-2.0%, P<0.0001). No differences were detected between seroconverters, i.e. those with recent rises in IgM and IgG antibodies, and those with acquired or congenital toxoplasmosis. Similar results were observed when congenitally infected ( n=38) and uninfected ( n=89) children under 1 year of age were compared (17.6+/-9.2% vs. 3.0+/-4.9%, P<0.0001). The sensitivity and specificity values of CD25 detection for diagnosis of congenital toxoplasmosis in infants were 95% and 89%, respectively, at a threshold value of 7% above control culture. The results show that specific cellular immunity is detectable in virtually all Toxoplasma-infected patients, including newborns. Detection of CD25 constitutes a simple, sensitive and specific test for diagnosis of congenital toxoplasmosis.

[Evaluation of prevention strategies for congenital toxoplasmosis: a critical review of medico-economic studies]

BACKGROUND

Congenital toxoplasmosis (CT) may lead to serious neurological or sensory consequences. A serological screening of women at risk of acquiring toxoplasmosis became mandatory in France, first during the visit before wedding (1978), then during the visit for pregnancy declaration (1985) and at last with a monthly follow-up during pregnancy since 1992. The efficacy and the profitability of the program was never assessed, in spite of the modification of the epidemiological context. However medico-economical studies were conducted in countries in which no prevention program for CT was available to determine the interest of an antenatal screening similar to the French one or of other prevention strategies.

METHODS

Eight studies comparing at least two strategies were selected. Methodologies used in those studies were analyzed by two independent readers with the help of a standardized scale. A score was calculated for each study.

RESULTS

Each study analyzed suffered from methodological limitations, in particular concerning the estimation of antenatal treatment efficacy, which could lead to invalidate their conclusion. The most reliable studies in regard to methodological guidelines, that is with the higher score, concluded that antenatal screening was not contributive. However, they could not be transposed directly in the present French situation, because of the difference of the epidemiological and economical context.

CONCLUSIONS

Given the difficulty to obtain a clear conclusion, it seems necessary to perform a rigorous decision analysis to identify the more effective and acceptable program in terms of human and financial costs for preventing congenital toxoplasmosis.

[Toxoplasma infections in early pregnancy: consequences and management]

OBJECTIVE

To assess the consequences for the fetus of maternal toxoplasma infection acquired during the first 8 weeks of gestation and to set guidelines on how to manage these maternal infections.

METHODS

Data were prospectively analyzed on 360 pregnancies followed-up in our department due to a toxoplasma infection during the 8 first weeks of pregnancy. Estimates of the risk of fetal infection were based on all cases, including those which could not be followed up until infection was ruled out or confirmed. Severity of infection was estimated based on ultrasound findings during pregnancy, neonatal and long-term postnatal clinical, neurological and ophthalmologic work up.

RESULTS

Out of the 360 included women, 336 gave birth to a live born child: 7 (2%) were infected, 302 (90%) were free of infection and follow-up was insufficient to conclude about the 27 (8%) remaining infants. The estimated risk of fetal infection ranged between 2 and 10% based on live born children and between 3 and 14% when the 24 interrupted pregnancies were included. At their last clinical evaluation at 70 months of age, all 7 children, including the 2 who had inactive peripheral eye lesions and the one who had a unique intracranial calcification were free of any ophthalmologic or neurological impairment.

CONCLUSION

Our study confirms that in the event of a maternal infection during the first 8 weeks of pregnancy the risk of fetal infection is low and results mainly in a spontaneous termination of pregnancy. Future parents should be assured that conversely to a common opinion, the prognosis of congenital toxoplasmosis in live-born children is good. For these early maternal infections as for those acquired later, we recommend immediate treatment with spiramycin, monthly ultrasound surveillance, amniocentesis and treatment with pyrimethamine and sulphamides if the PCR is positive. Abortion should be restricted to cases with ultrasound lesions

Cellular immune responses to recombinant antigens in pregnant women chronically infected with Toxoplasma gondii

The parasite Toxoplasma gondii can infect most mammals and birds, sometimes causing severe pathology. Primary infection during pregnancy can result in abortion or fetal defects. Host immunity, particularly cellular immunity towards antigenic peptides, can control infection, but an efficient vaccine is not yet available. We have evaluated T-cell responses to a crude soluble toxoplasma antigen (ST-Ag) and to five recombinant peptide antigens of cells in whole-blood cultures from 22 pregnant women with preexisting infections and from 7 pregnant negative controls. Cells from all infected patients but from none of the controls responded specifically to ST-Ag by expressing surface CD25 on culture. Responses to the recombinant antigens showed considerable variation between individuals. rGRA1 elicited a response in 16 of the 22 samples (73%), rSAG1 in 13, rGRA7 in 9, rGRA6-CT in 4, and rGRA6-NT in only 1. Most responding cells were CD4(+). Cells from infected subjects cultured with ST-Ag all released high levels of gamma interferon (IFN-gamma) into the culture supernatant (4,343 +/- 2,536 pg/ml). Cells from 12 patients released IFN-gamma after culture with rGRA1 (130 +/- 98 pg/ml), those from 10 patients released it after culture with rSAG1 (183 +/- 128 pg/ml), and those from 4 patients released it after culture with rGRA7 (324 +/- 374 pg/ml). Intensity of IFN-gamma production in response to the latter two recombinant antigens correlated with responses to ST-Ag (r = 0.61 and 0.53, respectively; P < 0.01). Interleukin-4 was always absent from supernatants of cells stimulated with toxoplasma antigens. The heterogeneity of human responses to individual recombinant toxoplasma antigens should be considered in the design of potential vaccines.

Sterol and fatty acid composition of Candida lusitaniae clinical isolates

The sterol and fatty acid compositions of four amphotericin B-resistant and of two amphotericin B-susceptible Candida lusitaniae clinical isolates were determined. A flow cytofluorometric susceptibility test (FCST) with a membrane potential-sensitive cationic dye was used as a complement to the conventional method for selecting the isolates. Compared to susceptible isolates, resistant ones showed a greatly reduced ergosterol content and changes in sterol composition, consistent with a defect in Delta8-->7 isomerase. Within each group, no correlation between the sterol or fatty acid pattern or composition and both the degree of in vitro susceptibility and FCST MIC was found.

Effect of prenatal treatment on mother to child transmission of Toxoplasma gondii: retrospective cohort study of 554 mother-child pairs in Lyon, France

BACKGROUND

The aim of prenatal serological screening for toxoplasmosis is to identify and treat maternal infection as soon as possible in order to prevent transmission of the parasite to the fetus. However, despite widespread provision of prenatal toxoplasma screening across Europe, the effectiveness of prenatal treatment is uncertain. The study aimed to determine the effect of the timing and type of prenatal treatment on mother to child transmission of Toxoplasma gondii.

METHOD

A cohort of 554 infected pregnant women were identified in Lyon, France between 1987 and 1995 and their children were followed to determine congenital infection status. We determined the effect of prenatal treatment on transmission by examining the effect of the delay between maternal seroconversion and start of treatment. We also compared the effect of the type of treatment and no treatment on the risk of mother to child transmission. Analyses were adjusted for gestation at maternal seroconversion.

RESULTS

Compared to treatment within 4 weeks from seroconversion, the adjusted odds ratios (OR) for mother to child transmission after a treatment delay of 4-7 weeks was 1.29 (95% CI : 0.61, 2.73) and after more than 8 weeks, 1.44 (95% CI : 0.60, 3.31). The adjusted OR associated with spiramycin alone compared with pyrimethamine-sulfadiazine treatment was 0.91 (95% CI : 0.45, 1.84) and the OR for no treatment compared with pyrimethamine-sulfadiazine treatment was 1.06 (95% CI : 0.37, 3.03).

CONCLUSIONS

The authors hypothesize that the absence of an effect of prenatal treatment is due to transmission before the start of treatment.

[Value of toxoplasma serology at delivery in women seronegative during pregnancy]

Monthly serological screening of non immune pregnant women, required by law in France, is sometimes interrupted before delivery. As a consequence, late maternal infections resulting in a high risk of vertical transmission with potentially severe late sequelae are not detected.

Serological rebound in congenital toxoplasmosis: long-term follow-up of 133 children

Although serological rebound is common in infants with congenital toxoplasmosis, clinical recommendations for management, in particular the need for additional treatment, vary. The goals of our retrospective cohort study in 133 consecutive children with congenital toxoplasmosis were to estimate the incidence and duration of the rebounds, identify predictive factors, assess the long-term risk of eye lesions and the need for treatment. We first estimated the incidence and duration of rebounds and identified predictive factors using an univariate analysis and a Cox model modified to include time-dependent variables. Two cohort studies were then conducted to compare the incidence density of secondary eye lesions in children who had a rebound versus no rebound, and among children who had a rebound after initial therapy, in those who received an additional course of treatment and in those who did not. Of the 133 children, 93 (70%) had at least one rebound during a mean follow-up of 95 months. Of those with one rebound diagnosed after initial treatment, 33 received an additional 3-month course of pyrimethamine/sulphadoxine and 48 were not treated. Intracranial calcification at birth was associated with an increased relative risk (RR) of rebound (RR = 2.601; P = 0.03), and treatment with pyrimethamine/sulphadoxine between 2 and 12 months of age with a decreased risk (RR = 0.3; P = 0.0845), whereas age of pregnancy at maternal infection, type of treatment during pregnancy and sex were not found to be predictive factors. There was no difference in incidence densities of secondary eye lesions in children without rebound (7/3,367 child-months) compared to those with at least one rebound (22/9,609 child-months) (RR = 1.10; 95% CI: 0.47-2.58), and, among the 81 children who had one rebound diagnosed after initial treatment, in those who received an additional course of treatment and in those who did not (RR = 0.72; 95% CI: 0.30-1.72).

CONCLUSION

serological rebound is common in children with congenital toxoplasmosis but, due to the risk and constraints, an additional course of treatment and more ophthalmological surveillance than currently practiced do not seem warranted.

Ecological comparison of the risks of mother-to-child transmission and clinical manifestations of congenital toxoplasmosis according to prenatal treatment protocol

We compared the relative risks of mother-to-child transmission of Toxoplasma gondii and clinical manifestations due to congenital toxoplasmosis associated with intensive prenatal treatment in Lyon and Austria, short term treatment in 51% of Dutch women, and no treatment in Danish women. For each cohort, relative risks were standardized for gestation at seroconversion. In total, 856 mother-child pairs were studied: 549 in Lyon, 133 in Austria, 123 in Denmark and 51 in The Netherlands. The relative risk for mother-to-child transmission compared to Lyon was 1.24 (95% CI: 0.88, 1.59) in Austria; 0.59 (0.41, 0.81) in Denmark; and 0.65 (0.37, 1.01) in The Netherlands. Relative risks for clinical manifestations compared with Lyon (adjusted for follow-up to age 3 years) were: Austria 0.19 (0.04, 0.51); Denmark 0.60 (0.13, 1.08); and The Netherlands 1.46 (0.51, 2.72). There was no clear evidence that the risk of transmission or of clinical manifestations was lowest in centres with the most intensive prenatal treatment.

Options for the pharmacotherapy of toxoplasmosis during pregnancy

Toxoplasmosis infection during pregnancy can cause stillbirths, severe mental retardations or ocular disorders that can also occur later in life and have a potential to relapse. As the disease is generally asymptomatic, diagnosis relies on serological tests. Primary prevention intends to prevent the infection of the fetus, while secondary prevention aims at reducing the severity of sequelae. Preventive attitudes regarding congenital toxoplasmosis differ according to countries. In Austria and France, a nationwide programme based on the screening of seronegative pregnant women and the treatment of all seroconversions has been implemented. The UK and Norway have rejected such a screening due to the lack of evidence of its efficacy. A review of published studies showed that no randomised controlled trials have been conducted. The only available data come from retrospective studies and are methodologically flawed. The impact of chemotherapy on primary and secondary prevention still needs to be assessed. This lack of evidence results in conflicting attitudes that increase the anxiety already raised in pregnant women and doctors by the occurrence of a maternal toxoplasmosis during pregnancy. Before making any change in preventative strategy, it is of utmost importance to increase our knowledge on treatment efficacy through proper randomised trials of existing drugs and of new potentially active compounds.

[Side effects of chemoprophylaxis: real or imagined?]

Prescribing chemoprophylaxis against malaria is a medical act which is often controversial. The choice of appropriate molecule depends on destination, length of stay and tolerance to a given product. This latter aspect is difficult to evaluate. Among the three most commonly used drugs for malarial prevention--Savarine, Lariam and doxycycline--the first enjoys the reputation of being well tolerated, the second is perceived as being poorly tolerated and the third, little used until now, is suspected of serious complications. It is impossible to say by reviewing the available literature, which of these three molecules is indeed the least well tolerated, but the studies have followed heterogeneous evaluation methods. We propose that the various scientific associations concerned by the issue draw together an information sheet on side effects so as to encourage practioners to investigate all cases of intolerance of antimalarial drugs.

[Congenital toxoplasmosis. Transitory negative serology]

OBJECTIVES

Toxoplasmosis serology may become temporarily negative in children with congenital toxoplasmosis, leading to a risk of misdiagnosis and inadequate surveillance. The purpose of our work was to better understand the time course of toxoplasmosis serology which has not been studied specifically and to propose practical recommendations.

PATIENTS AND METHODS

We conducted a prospective study in 217 children born with congenital toxoplasmosis between January 1988 and December 1997. Clinical, ophthalmological and serology data were collected every three months during their first year of life then every six months until three years of age and every year thereafter for all patients. Negative serology was defined as the absence of IgG at indirect immunofluorescence and ELISA (enzyme linked immunosorbent assay) and by the absence of IgM at ISAGA (immunosorbent agglutination assay).

RESULTS

During the mean follow-up of 66 +/- 33 months (range 12-126 months), 33 children (15%) presented a period where the toxoplasmosis serology (ELISA and indirect immunofluorescence) was negative for a transient period reaching a mean 5 months. The dye test was performed in 25 of these children and was negative in 6 (24%). Among the negative conversions observed at routine testing, 73% occurred in children taking pyrimethamine/sulfadoxin therapy and the others occurred a mean 11.7 months after interruption of treatment. There was a positive association between maternal treatment and transient seronegativity in the cases where the maternal contamination had occurred during the first 2 trimesters of pregnancy. The serology became positive again in 30 of the 33 children (91%) and in 22 children there was a rebound. At last follow-up, the 3 other children still had negative serology (mean duration 35 months, range 3-62 months).

CONCLUSION

Transient negative toxoplasmosis serology is a frequent phenomenon in children with congenital toxoplasmosis. Although the underlying pathophysiological mechanism remains unknown, it is crucial to avoid questioning the initial diagnosis of congenital toxoplasmosis and to continue regular routine monitoring.

Prenatal diagnosis using polymerase chain reaction on amniotic fluid for congenital toxoplasmosis

OBJECTIVE

To evaluate sensitivity, specificity, and predictive values of a prenatal amniotic fluid (AF) polymerase chain reaction (PCR) test for diagnosis of congenital toxoplasmosis.

METHODS

A multicenter prospective study was done on 271 women with proved primary Toxoplasma infection during pregnancy and who had amniocentesis for prenatal diagnosis by PCR. Live-born infants were eligible for analysis only if a serologic follow-up could assess a definitive infection status.

RESULTS

Of the 270 evaluable cases, 75 were congenitally infected, 48 of whom had a positive PCR at prenatal diagnosis. Overall sensitivity of PCR on AF was estimated at 64% (95% confidence interval [CI] 53.1%, 74.9%), negative predictive value of 87.8% (95% CI 83.5%, 92.1%), whereas specificity and positive predictive value were 100% (95% CIs 98%, 100% and 92.3%, 100%, respectively). Among cases with congenital toxoplasmosis, there were no significant differences between those with positive or negative PCR with regard to median gestational age at maternal infection, interval between maternal infection and amniocentesis, or duration of treatment before amniocentesis. However, sensitivity of PCR was found to be significantly higher for maternal infections that occurred between 17 and 21 weeks' gestation (P <.02).

CONCLUSION

A negative PCR of AF cannot rule out congenital infection. In this case, continuation of treatment with spiramycin combined with ultrasonographic follow-up and postnatal follow-up are warranted. Our results also suggest presumptive treatment combining pyrimethamine and sulfonamides in case of maternal infection occurring late in pregnancy.

Improved detection of amphotericin B-resistant isolates of Candida lusitaniae by Etest

Both intrinsic and acquired resistance to amphotericin B have been documented for Candida lusitaniae. Amphotericin B remains the drug of choice for many critical fungal infections, and the detection of resistance is essential to monitor treatment effectively. The limitations of the National Committee for Clinical Laboratory Standards (NCCLS) reference methodology for detection of amphotericin B resistance are well documented, and several alternative methods have been proposed. Etest assays with RPMI and antibiotic medium 3 (AM3) agar were compared to the NCCLS M27-A broth macrodilution method using AM3 for amphotericin B resistance testing with 49 clinical isolates of C. lusitaniae. The panel included nine isolates with known or presumed resistance to amphotericin B on the basis of in vivo and/or in vitro data. The distribution of amphotericin B MICs by Etest with RPMI ranged from 0. 032 to 16 microg/ml and was bimodal. All of the putatively resistant isolates were inhibited by amphotericin B at >/=0.38 microg/ml and could be categorized as resistant using this breakpoint. Etest with AM3 yielded a broader amphotericin B MIC range (0.047 to 32 microg/ml), and there were six putatively resistant isolates for which MICs were >1 microg/ml. The separation of putatively susceptible and resistant isolates was less obvious. Broth macrodilution with AM3 generated a unimodal distribution of MICs (ranging from 0.032 to 2 microg/ml) and failed to discriminate most of the putatively resistant isolates at both 24 and 48 h. Etest using RPMI and, to a lesser extent, using AM3 provided better discrimination between amphotericin B-resistant and -susceptible isolates of C. lusitaniae.

Evidence of cerebrospinal fluid free kappa light chains in AIDS patients with Toxoplasma gondii encephalitis

Cerebrospinal fluid (CSF) free light chains of kappa or lambda (FLC kappa/lambda) type were investigated by affinity mediated blotting technique (AMI) and ELISA in 28 patients of which nine with AIDS and Toxoplasma gondii encephalitis (AIDS, TE), 11 with AIDS with or without other CNS AIDS-related opportunistic infections (non-TE AIDS) and eight control patients with or without inflammatory neurological disorders (control group). CSF restricted oligoclonal FLC bands either of k or lambda isotype or both were found by AMI in 18 (90%) out of 20 AIDS patients, while a CSF pattern predominantly characterized by FkappaLC rather than FlambdaLC was observed in eight (88.8%) out of nine TE patients. No FLC components were detected in the matched sera of TE or non-TE AIDS patients or in the CSF and sera from control group. The anti-parasite-specific FkappaLC CSF/serum mean levels and the T. gondii-specific FkappaLC index values were found by ELISA to be significantly more elevated in TE patients when compared to non-TE AIDS or control group. These findings suggest that the increased production of T. gondii-specific FkappaLC could provide insights into pathogenesis of reactivated TE in immunocompromised patients and may have important diagnostic usefulness.

Toxoplasma encephalitis: influence of the vehicle on the efficacy of different doses of 2',3'-dideoxyinosine in mice

In this study we investigated the effect of the antiretroviral molecule 2',3'-dideoxyinosine (Videx) against cerebral cysts in a murine model of toxoplasmic encephalitis caused by a wild cystic strain of Toxoplasma gondii. The role of the vehicle was also studied. Three doses were used: 50, 100 and 150 mg/kg of body weight/day. The doses of 50 and 150 mg/kg were prepared by dissolving pure 2',3'-dideoxyinosine powder in Maalox suspension before gavaging the mice; the dose of 100 mg/kg was prepared by grinding tablets of Videx that were suspended in water. A decrease in the number of cysts and a morphological modification of them were noted from day 15 with the lowest dose. The most important decrease could be observed with the dose of 100 mg/kg/d. After 30 days of treatment with this dose, 65% of the cysts were destroyed compared to controls. For the doses of 50 and 150 mg/kg/d prepared with Maalox, 36% and 51% of the cysts were destroyed respectively. So ddI has an effect on the cerebral cysts of T. gondii even at a low dose. The galenic formulation influences its action since the doses prepared with Maalox were less efficient than those prepared from ground tablets.

Effects of artesunate, dihydroartemisinin, and an artesunate-dihydroartemisinin combination against Toxoplasma gondii

The effect of artesunate and its metabolite dihydroartemisinin against the cerebral cysts of Toxoplasma gondii was studied. In vitro experiments were performed with the THP-1 cell line and showed an inhibition of parasite growth of approximately 70% with 0.1-0.5 microg/ml of dihydroartemisinin for 96 hr. However, with artesunate, dihydroartemisinin, or a combination (50:50) of them, the number of tachyzoites decreased approximately 40-50% and they appeared motionless. Fifty-eight to 72 hr after washing of the tachyzoites and THP-1 cells in culture, parasitized cells reappeared. In vivo, the 50:50 artesunate-dihydroartemisinin combination produced a decrease in cerebral cysts of approximately 40% after only 5 days of treatment. However, transplantations into naive mice using brains of treated mice gave positive results.

Treatments for toxoplasmosis in pregnancy

BACKGROUND

Toxoplasmosis is a widespread parasitic disease and usually causes no symptoms. However, infection of pregnant women may cause congenital infection, resulting potentially in mental retardation and blindness in the infant.

OBJECTIVES

The objective of this review was to assess whether or not treating toxoplasmosis in pregnancy reduces the risk of congenital toxoplasma infection and improves infant outcomes.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group trials register was searched. An electronic search was performed using the key words 'congenital and toxoplasmosis' on the following databases: MEDLINE (1966-07/1997), Embase (1993-07/1997), Pascal (French) (1990-1997), Biological Abstracts (1993-1995) and the Cochrane Controlled Trials Register. There was also contact with experts in the field, including those in the European Research Network on Congenital Toxoplasmosis.

SELECTION CRITERIA

Randomised controlled trials of antibiotic treatment versus no treatment of pregnant women with proven or likely acute Toxoplasma infection, with outcomes in the children reported. We also inspected relevant reports of less robust experimental studies in which there were (non randomly allocated) control groups, although it was not planned to include such data in the primary analysis.

DATA COLLECTION AND ANALYSIS

Reports of possibly eligible studies were scrutinised by two investigators.

MAIN RESULTS

Out of the 2591 papers identified, none met the inclusion criteria.

REVIEWER'S CONCLUSIONS

Despite the large number of studies performed over the last three decades we still do not know whether antenatal treatment in women with presumed toxoplasmosis reduces the congenital transmission of Toxoplasma gondii. Screening is expensive, so we need to evaluate the effects of treatment, and the impact of screening programmes. In countries where screening or treatment is not routine, these technologies should not be introduced outside the context of a carefully controlled trial.

Purine pathway enzymes in a cyst forming strain of Toxoplasma gondii

The activities of purine salvage enzymes in tachyzoites from a cyst-forming strain of Toxoplasma gondii were determined using HPLC. Six enzymes were assayed both in vitro and in vivo: adenosine deaminase, guanine deaminase, purine nucleoside phosphorylase, xanthine oxidase, hypoxanthine-guanine phosphoribosyltransferase and adenine phosphoribosyltransferase. In vitro, the tachyzoites were cultured in the human myelomonocytic cell line THP-1, for 24 h to 96 h. Neither guanine deaminase nor hypoxanthine-guanine phosphoribosyltransferase activity was detected in 24 and 96 h cultures. In vivo, in controls and infected animals, the purine nucleoside phosphorylase and adenosine deaminase activities were the most important activities both in sera and cerebral tissue in comparison with the other activities. It was also noted that the infection modified the enzymatic activities of this purine salvage pathway, in particular, the guanine deaminase cerebral activity of infected mice was 20-fold lower than the value of controls. The treatment of mice with 2',3'-dideoxyinosine, a purine analog, at the dose of 100 mg.kg(-1).d for 30 days, induced an important increase of all enzymatic activities in the brains in comparison with control animals. These data suggest that one target of 2',3'-dideoxyinosine is the purine metabolism.

Flow cytometric application of the Sabin and Feldman dye test in the diagnosis of toxoplasmosis

Although time-consuming and requiring live parasites, the Sabin and Feldman dye test (DT) is still considered the 'gold standard' among the serological tests for toxoplasmosis diagnosis. The present study was initiated to compare detection of dead parasites using optical microscopy with flow cytometry and a fluorescent nonvital dye, propidium iodide. After incubation with sera (N = 150) and a complement source, tachyzoites were washed, then stained using a fluorescein-conjugated Toxoplasma-specific antiserum. Dead tachyzoites were detected by flow cytometry after addition of propidium iodide. Intra- and inter-assay reproducibilities of percentages of dead parasites varied between 7 and 14%, and 8 and 21%, respectively. When comparing flow cytometry with the classical DT, no discrepancy was noted for positive (N = 118) and negative sera (N = 32). Correlation was good (r = 0.85) for positive sera. In conclusion, when easily available, flow cytometry is a very sensitive, specific and time-sparing method to detect specific antibodies to Toxoplasma gondii.