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

40 years neonatology : An academic life

BACKGROUND

A complete review of the development of neonatology in the last 40 years would probably require a compendium with several volumes, to bring to view the remarkable improvements in survival rates and neurodevelopmental outcomes of ill babies in Austria, most industrial countries and to some extent worldwide. The challenge I had to solve here was to integrate my own contributions to the field of neonatology during this period and particularly the contributions of my team from the Division of Neonatology and Pediatric Intensive Care Medicine, Department of Pediatrics and Adolescence Medicine, Medical University Vienna where I was working first as an intern and resident and later had the privilege to become head of department.

AIM

This very personal review was conceived to showcase the milestones of neonatology where, in my opinion, our department made some meaningful contributions in research and clinical practice during the past 40 years.

METHODS

A total of 10 areas of interest were selected which most likely influenced survival rates of preterm infants born at increasingly younger gestational ages and ameliorated long-term clinical and neurodevelopmental outcomes, including: 1) Construction and continuous modernization of neonatal intensive care units (NICUs). 2) Installation of the "Regionalization Program for NICUs in Vienna". 3) Treatment of respiratory distress syndrome (RDS) of premature babies. 4) Fine tuning of glucose metabolism for growth and outcome. 5) Neurodevelopmental care. 6) Neonatal hematology. 7) Infection control. 8) The toxoplasma screening program. 9) The newborn screening program. 10) Quality control: the Vermont Oxford Neonatal Network (VONN).

RESULTS

Over the past four decades advancements in research and technology have allowed a transformative development of neonatal medicine. Survival rates without increased morbidity for very premature infants with gestational ages reaching to what we consider nowadays the border of viability have constantly increased. In my professional life as a neonatologist in Austria I have had the possibility to support and shape some of these developments together with my team.

CONCLUSION

As we look ahead it is imperative to build upon the progress made, harnessing the power of science and technology to further improve the survival and quality of life for preterm infants in Austria and worldwide. At the same time, neonatology must continue to prioritize ethical reflection and education, fostering a culture of integrity, interdisciplinary collaboration, and the development of guidelines and protocols that uphold ethical standards while addressing the evolving needs and complexities of neonatal medicine.

Long-Term Outcomes in Children with Congenital Toxoplasmosis-A Systematic Review

Even in the absence of manifestations at birth, children with congenital toxoplasmosis (CT) may develop serious long-term sequelae later in life. This systematic review aims to present the current state of knowledge to base an informed decision on how to optimally manage these pregnancies and children. For this, a systematic literature search was performed on 28 July 2022 in PubMed, CENTRAL, ClinicalTrials.gov, Google Scholar and Scopus to identify all prospective and retrospective studies on congenital toxoplasmosis and its long-term outcomes that were evaluated by the authors. We included 31 research papers from several countries. Virulent parasite strains, low socioeconomic status and any delay of treatment seem to contribute to a worse outcome, whereas an early diagnosis of CT as a consequence of prenatal screening may be beneficial. The rate of ocular lesions in treated children increases over time to 30% in European and over 70% in South American children and can be considerably reduced by early treatment in the first year of life. After treatment, new neurological manifestations are not reported, while ocular recurrences are observed in more than 50% of patients, with a mild to moderate impact on quality of life in European cohorts when compared to a significantly reduced quality of life in the more severely affected South American children. Though CT is rare and less severe in Europe when compared with South America, antenatal screening is the only effective way to diagnose and treat affected individuals at the earliest possible time in order to reduce the burden of disease and achieve satisfying outcomes.

The disease burden of ocular toxoplasmosis in Denmark in 2019: Estimates based on laboratory testing of ocular samples and on publicly available register data

Background

Toxoplasma gondii is an important zoonotic protozoan parasite with worldwide distribution. Information on the contribution of ocular toxoplasmosis to the disease burden caused by this parasite is limited or lacking from many countries.

Methods

We estimated the minimum occurrence of ocular toxoplasmosis in Denmark using results from direct detection of T. gondii DNA with qPCR and determination of the Goldmann-Witmer coefficient on ocular samples submitted by ophthalmological clinics and departments to the national reference laboratory in 2003–2019. In addition, we inferred incidence estimates using retrospective data that are publicly available in the National Patient Register, and we used unstructured expert elicitation as the basis for sensitivity analyses. We estimated the disease burden of ocular toxoplasmosis in 2019 in disability-adjusted life years (DALYs).

Findings

Ocular samples from 263 individuals (median age 57 years, range 2–88) had been tested with at least one of the methods during 2003–2019, and 42 (16%) tested positive (median age 65 years, range 14–85). In 2019, five (16%) of 31 tested individuals were positive, giving a minimum annual incidence estimate of 0.09 per 100.000 population. From this, we calculated a disease burden of at least 4 DALYs (95% confidence interval, 3–5). The age range suggested that this figure represented postnatally acquired ocular toxoplasmosis. The disease burden of ocular toxoplasmosis due to congenital toxoplasmosis has been previously estimated to be at least 12 DALYs, resulting in an estimated minimum total disease burden due to ocular toxoplasmosis of 16 DALYs. In 2005–2018, the mean annual number of diagnoses of ocular toxoplasmosis reported to the National Patient Register was 186, and the corresponding disease burden estimate was 134 DALYs (95% confidence interval, 113–158). Sensitivity analyses focusing on incidence and severity resulted in disease burden estimates in the range of 9–523 DALYs.

Interpretation

Because most diagnoses of ocular toxoplasmosis are based on clinical observations, ophthalmoscopy, and serology without confirmatory testing, the disease burden caused by ocular toxoplasmosis is likely substantially higher than our minimum estimates. Our results indicate that ocular toxoplasmosis contributes to the disease burden caused by T. gondii in Denmark, but uncertainty about the incidence and severity precludes reliable estimation of its importance.

Congenital toxoplasmosis: What is the evidence for chemoprophylaxis to prevent fetal infection?

Although prenatal diagnosis and prenatal and neonatal therapy of congenital toxoplasmosis are available, there is controversy concerning the effectiveness of prophylaxis to prevent placental transmission. Experimental, parasitological, and clinical data suggest a "window of opportunity" following maternal infection. Among medications active against Toxoplasma gondii, mainly spiramycin (Spy) and pyrimethamine + sulfonamide combinations (P-S) have been evaluated. Results from observational studies suffered treatment bias, since prescriptions differed according to the gestational age at seroconversion, which is the major risk factor for transmission, and many lacked precise timing. Some large retrospective studies found no difference in transmission according to prophylactic treatment, but transmission was lower when treatment started promptly after maternal seroconversion. A few recent studies adjusting for timing of infection observed lower transmission in case of P-S than other or no prophylaxis. In the only randomized controlled trial, transmission was lower with P-S than S (18.5% vs 30%, P = .147); this association was strengthened when the treatment was started within 3 weeks of seroconversion, and the incidence of fetal cerebral ultrasound signs was significantly reduced in the P-S group. Rapid initiation of prophylactic therapy following maternal infection, which is usually asymptomatic, requires systematic screening for maternal seroconversion during pregnancy.

Macrophage Migration Inhibitory Factor (MIF) Prevents Maternal Death, but Contributes to Poor Fetal Outcome During Congenital Toxoplasmosis

Migration inhibitory factor (MIF) is a pro-inflammatory cytokine that plays important roles in physiology, pathology, immunology and parasitology, including the control of infection by protozoa parasites such as Toxoplasma gondii. As the MIF function in congenital toxoplasmosis is not fully elucidated yet, the present study brings new insights for T. gondii infection in the absence of MIF based on pregnant C57BL/6MIF-/- mouse models. Pregnant C57BL/6MIF-/- and C57BL/6WT mice were infected with 05 cysts of T. gondii (ME49 strain) on the first day of pregnancy (dop) and were euthanized at 8 dop. Non-pregnant and non-infected females were used as control. Our results demonstrated that MIF-/- mice have more accentuated change in body weight and succumbed to infection first than their WT counterparts. Otherwise, pregnancy outcome was less destructive in MIF-/- mice compared to WT ones, and the former had an increase in the mast cell recruitment and IDO expression and consequently presented less inflammatory cytokine production. Also, MIF receptor (CD74) was upregulated in MIF-/- mice, indicating that a compensatory mechanism may be required in this model of study. The global absence of MIF was associated with attenuation of pathology in congenital toxoplasmosis, but resulted in female death probably because of uncontrolled infection. Altogether, ours results demonstrated that part of the immune response that protects a pregnant female from T. gondii infection, favors fetal damage.

Prenatal education for congenital toxoplasmosis

BACKGROUND

Congenital toxoplasmosis is considered a rare but potentially severe infection. Prenatal education about congenital toxoplasmosis could be the most efficient and least harmful intervention, yet its effectiveness is uncertain.

OBJECTIVES

To assess the effects of prenatal education for preventing congenital toxoplasmosis.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 May 2015), and reference lists of relevant papers, reviews and websites.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials of all types of prenatal education on toxoplasmosis infection during pregnancy. Cluster-randomized trials were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy.

MAIN RESULTS

Two cluster-randomized controlled trials (RCTs) (involving a total of 5455 women) met the inclusion criteria. The two included trials measured the effectiveness of the intervention in different ways, which meant that meta-analysis of the results was not possible. The overall quality of the two studies, as assessed using the GRADE approach, was low, with high risk of detection and attrition bias in both included trials.One trial (432 women enrolled) conducted in Canada was judged of low methodological quality. This trial did not report on any of the review's pre-specified primary outcomes and the secondary outcomes reported results only as P values. Moreover, losses to follow-up were high (34%, 147 out of 432 women initially enrolled). The authors concluded that prenatal education can effectively change pregnant women's behavior as it increased pet, personal and food hygiene. The second trial conducted in France was also judged of low methodological quality. Losses to follow-up were also high (44.5%, 2233 out of 5023 women initially enrolled) and differential (40% in the intervention group and 52% in the control group). The authors concluded that prenatal education for congenital toxoplasmoses has a significant effect on improving women's knowledge, whereas it has no effect on changing women's behavior. In this trial 17/3949 pregnant women seroconverted for toxoplasmosis: 13/2591 (0.5%) in the intervention group and 4/1358 (0.3%) in the control group. The rate of seroconversion detected during the study did not differ between groups (risk ratio (RR) 1.70, 95% confidence interval (CI) 0.56 to 5.21; participants = 3949; studies = one, low quality evidence). The number of events was too small to reach conclusions about the effect of prenatal education on seroconversion rate during pregnancy.No other randomized trials on the effect of prenatal education on congenital toxoplasmosis rate, or toxoplasmosis seroconversion rate during pregnancy were detected.

AUTHORS' CONCLUSIONS

Even though primary prevention of congenital toxoplasmosis is considered a desirable intervention, given the lack of related risks compared to secondary and tertiary prevention, its effectiveness has not been adequately evaluated. There is very little evidence from RCTs that prenatal education is effective in reducing congenital toxoplasmosis even though evidence from observational studies suggests it is. Given the lack of good evidence supporting prenatal education for congenital toxoplasmosis prevention, further RCTs are needed to confirm any potential benefits and to further quantify the impact of different sets of educational intervention.

The Austrian Toxoplasmosis Register, 1992-2008

BACKGROUND

We aimed to determine the incidence of primary gestational infections with Toxoplasma gondii and congenital toxoplasmosis in Austria, a country with a nationwide prenatal serological screening program since 1974.

METHODS

We analyzed retrospective data from the Austrian Toxoplasmosis Register of pregnant women with Toxoplasma infection and their offspring with births between 1992 and 2008, identified by the prenatal mandatory screening program. Treatment was administered to women from diagnosis of a Toxoplasma infection until delivery. Infected infants were treated up to 1 year of life routinely. Clinical manifestations in infected infants were monitored at least for 1 year and documented in the register.

RESULTS

The Austrian Toxoplasmosis Register included 2147 pregnant women with suspected Toxoplasma infection. Annually, 8.5 per 10 000 women acquired Toxoplasma infection during pregnancy, and 1.0 per 10 000 infants had congenital toxoplasmosis (13% mean transmission rate). Our data showed that women treated according to the Austrian scheme had a 6-fold decrease in the maternofetal transmission rate compared to women without treatment.

CONCLUSIONS

Results from the Austrian Toxoplasmosis Register show the efficiency of the prenatal screening program. Our results are of clinical relevance for infants, healthcare systems, and policy makers to consider preventive Toxoplasma screening as a potential tool to reduce the incidence of congenital toxoplasmosis.

Congenital Toxoplasmosis

Toxoplasmosis is caused by infection with the parasite Toxoplasma gondii. It is one of the most common parasitic infections in humans and is most typically asymptomatic. However, primary infection in a pregnant woman can cause severe and disabling disease in the developing fetus. Recent developments have included increased understanding of the role of parasite genotype in determining infectivity and disease severity. Risk factors for acquisition of infection have been better defined, and the important role of foodborne transmission has been further delineated. In addition, strategies have emerged to decrease mother-to-child transmission through prompt identification of acutely infected pregnant women followed by appropriate treatment. Refined diagnostic tools, particularly the addition of immunoglobulin G avidity testing, allow for more accurate timing of maternal infection and hence better decision making during pregnancy. Congenitally infected children can be treated, beginning in utero and continuing through the first year of life, to ameliorate the severity of disease. However, despite these many advances in our understanding of congenital toxoplasmosis prevention and treatment, significant areas of study remain: we need better drugs, well defined strategies for screening of pregnant women, improved food safety, and improved diagnostic tests.

Assessment of laboratory methods used in the diagnosis of congenital toxoplasmosis after maternal treatment with spiramycin in pregnancy

BACKGROUND

The different laboratory methods used in the diagnosis of congenital toxoplasmosis have variable sensitivity and specificity. There is no evidence to prove that maternal treatment reduces the risk of fetal infection. The purpose of this study was to assess methods for the confirmation of congenital toxoplasmosis after maternal treatment with spiramycin during pregnancy, and to evaluate the effect of this treatment on clinical manifestations of the disease in newborns (NB).

METHODS

This was a community-based, cross-sectional study of acute toxoplasmosis in newborns at risk of acquiring congenital infection. Participating newborns were born in the Clinical Hospital Maternity Ward of the Federal University of Goiás. Eligible participants were divided into 2 groups: group 1 consisted of 44 newborns born to mothers treated with spiramycin during pregnancy and group 2 consisted of 24 newborns born to mothers not treated with spiramycin during pregnancy because the diagnosis of toxoplasmosis was not performed. The sensitivity and specifity of PCR for T. gondii DNA in peripheral blood and serological testing for specific anti-T. gondii IgM and IgA, and the effects of maternal spiramycin treatment on these parameters, were determined by associating test results with clinical manifestations of disease.

RESULTS

The sensitivity of the markers (T. gondii DNA detected by PCR, and the presence of specific anti-T. gondii IgM and IgA) for congenital toxoplasmosis was higher in group 2 than in group 1 (31.6, 68.4, 36.8% and 3.7, 25.9, 11.1% respectively). Even with a low PCR sensitivity, the group 2 results indicate the importance of developing new techniques for the diagnosis of congenital toxoplasmosis in newborns. Within group 1, 70.4% of the infected newborns were asymptomatic and, in group 2, 68.4% showed clinical manifestations of congenital toxoplasmosis.

CONCLUSIONS

The higher proportion of infants without clinical symptoms in group 1 (70.4%) suggests the maternal treatment with spiramycin delays fetal infection, reducing the clinical sequelae of the disease in newborns. Given the low sensitivity of the tests used, when there is suspicion of congenital transmission several serological and parasitological tests are required in order to confirm or exclude congenital toxoplasmosis in newborns.

A meta analysis on risks of adverse pregnancy outcomes in Toxoplasma gondii infection

Objective

Quantified risks of congenital Toxoplasma gondii infection and abnormal pregnancy outcomes following primary maternal infection were evaluated with meta- analysis based on published studies.

Methods

The related literatures were searched in multiple literature databases regardless of languages. Odds ratio (OR) and 95% confidence interval (CI) were used to evaluate the risks of vertical transmission of Toxoplasma gondii and abnormal pregnancy outcomes following primary maternal infection with meta-analysis.

Results

53 of the 2632 searched literatures were included in our analysis. The incidence of abnormal pregnancy outcomes in T. gondii infected pregnant women (infected group) was significantly higher than that in the uninfected pregnant women (control group) (OR = 5.10; 95% CI, 3.85–6.75). Toxoplasma gondii infection rate in the abnormal-pregnancy-outcome group was significantly higher than in the normal-pregnancy group (OR = 3.71; 95% CI, 3.31–4.15). The pooled rate of vertical transmission was 20% (95% CI, 15%–26%) in maternal infection of T. gondii. The incidences of vertical transmission in women who were infected in the first, second or third trimester of pregnancy were 5% (95%CI, 2%–16%), 13% (95%CI, 7%–23%), and 32% (95%CI, 24%–41%), respectively. The rates of vertical transmission in women who were treated with spiramycin-only, PSF (pyrimethamine + sulfadiazine + folinic acid) or PS (pyrimethamine + sulfadiazine) combined with spiramycin, or other untypical treatments were 13% (95%CI, 7%–22%), 13%(95%CI, 7%–25%), and 24%(95%CI, 18%–32%), respectively.

Conclusions

Toxoplasma gondii infection can result in adverse pregnancy outcomes in pregnant women. The pooled rate of vertical transmission was 20% in maternal infection and the incidences of vertical transmission increased in the first, second or third trimester of pregnancy. The pooled rates of transmission in groups treated with spiramycin-only, PSF or PS combined with spiramycin, or other untypical treatments were not significantly different.

Prenatal education for congenital toxoplasmosis

BACKGROUND

Congenital toxoplasmosis is considered a rare but potentially severe infection. Prenatal education about congenital toxoplasmosis could be the most efficient and least harmful intervention, yet its effectiveness is uncertain.

OBJECTIVES

To assess the effects of prenatal education for preventing congenital toxoplasmosis.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (15 January 2012), PubMed (1966 to 15 January 2012), EMBASE (1980 to 15 January 2012), CINAHL (1982 to 15 January 2012), LILACS (1982 to 15 January 2012), IMEMR (1984 to 15 January 2012), and reference lists of relevant papers, reviews and websites.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials (RCTs) of all types of prenatal education on toxoplasmosis infection during pregnancy. Cluster-randomized trials were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and study quality. Two review authors extracted data. Data were checked for accuracy.

MAIN RESULTS

Two cluster-randomized controlled trials (involving a total of 5455 women) met the inclusion criteria. The two included trials measured the effectiveness of the intervention in different ways which meant that meta-analysis of the results was not possible One trial (432 women enrolled) conducted in Canada was judged of low methodological quality. The authors did not report measure of association but only provided P values (P less than 0.05) for all outcomes. Moreover, losses to follow-up were high (34%, 147 out of 432 women initially enrolled). The authors concluded that prenatal education can effectively change pregnant women's behavior as it increased pet, personal and food hygiene. The second trial conducted in France was also judged of low methodological quality. Losses to follow-up were high (44.5%, 2233 out of 5023 women initially enrolled) and differential (40% in the intervention group and 52% in the control group). The authors concluded that prenatal education for congenital toxoplasmoses has a significant effect on improving women's knowledge whereas it has no effect on changing women's behavior. In this trial 17/3949 pregnant women seroconverted for toxoplasmosis: 13/2591 (0.5%) in the intervention group and 4/1358 (0.3%) in the control group. The number of events was too small to reach conclusions about the effect of prenatal education on seroconversion rate during pregnancy.No other randomized trials on the effect of prenatal education on congenital toxoplasmosis rate, or toxoplasmosis seroconversion rate during pregnancy were detected.

AUTHORS' CONCLUSIONS

Even though primary prevention of congenital toxoplasmosis is considered a desirable intervention, given the lack of related risks compared to secondary and tertiary prevention, its effectiveness has not been adequately evaluated. There is very little evidence from RCTs that prenatal education is effective in reducing congenital toxoplasmosis even though evidence from observational studies suggests it is. Given the lack of good evidence supporting prenatal education for congenital toxoplasmosis prevention, further RCTs are needed to confirm any potential benefits and to further quantify the impact of different sets of educational intervention.

Enzyme-linked immunosorbent assay using recombinant SAG1 antigen to detect Toxoplasma gondii-specific immunoglobulin G antibodies in human sera and saliva

Serologic detection of Toxoplasma gondii IgG antibodies is widely accepted as a means to determine immune status and susceptibility to Toxoplasma infection during pregnancy. However, current commercial kits present some drawbacks, such as a requirement for whole-parasite antigen preparation or interassay variability. To address these problems, the purpose of this study was to produce a whole sequence of the recombinant T. gondii SAG1 antigen (rSAG1) to assess its diagnostic performance in Toxoplasma IgG screening and to explore a saliva-based method as a noninvasive alternative to serum-based testing. rSAG1 was expressed in recombinant bacteria as inclusion bodies, purified through one-step affinity chromatography, and refolded in native form by dialysis. A large amount was obtained, and the specific antigen immunoreactivity was confirmed by immunoblotting. Two rSAG1-based enzyme-linked immunosorbent assays (ELISAs) applied to paired serum and saliva samples were designed. The rSAG1-based ELISA evaluation consisted of testing intrinsic sensitivity and specificity of 49 serum samples from patients immune to toxoplasmosis and 42 serum samples from nonimmune controls identified by routinely used kits. To assess agreement between serum-based and saliva-based tests, the positive percent agreement (PPA) and negative percent agreement (NPA) between the 2 tests were estimated. The rSAG1 serum-based ELISA detected specific IgG with 100% sensitivity and specificity. The PPA and NPA between the serum-based and saliva-based tests varied according to the selected optical density threshold in saliva. Thus, for a selected cutoff of 0.14, the PPA was 100% and the NPA was 88.1%, whereas for a selected cutoff of 0.29, the PPA was 67.3% and the NPA was 100%.

Toxoplasmosis in humans and animals in Brazil: high prevalence, high burden of disease, and epidemiology

Infections by the protozoan parasite Toxoplasma gondii are widely prevalent in humans and animals in Brazil. The burden of clinical toxoplasmosis in humans is considered to be very high. The high prevalence and encouragement of the Brazilian Government provides a unique opportunity for international groups to study the epidemiology and control of toxoplasmosis in Brazil. Many early papers on toxoplasmosis in Brazil were published in Portuguese and often not available to scientists in English-speaking countries. In the present paper we review prevalence, clinical spectrum, molecular epidemiology, and control of T. gondii in humans and animals in Brazil. This knowledge should be useful to biologists, public health workers, veterinarians, and physicians. Brazil has a very high rate of T. gondii infection in humans. Up to 50% of elementary school children and 50-80% of women of child-bearing age have antibodies to T. gondii. The risks for uninfected women to acquire toxoplasmosis during pregnancy and fetal transmission are high because the environment is highly contaminated with oocysts. The burden of toxoplasmosis in congenitally infected children is also very high. From limited data on screening of infants for T. gondii IgM at birth, 5-23 children are born infected per 10 000 live births in Brazil. Based on an estimate of 1 infected child per 1000 births, 2649 children with congenital toxoplasmosis are likely to be born annually in Brazil. Most of these infected children are likely to develop symptoms or signs of clinical toxoplasmosis. Among the congenitally infected children whose clinical data are described in this review, several died soon after birth, 35% had neurological disease including hydrocephalus, microcephaly and mental retardation, 80% had ocular lesions, and in one report 40% of children had hearing loss. The severity of clinical toxoplasmosis in Brazilian children may be associated with the genetic characteristics of T. gondii isolates prevailing in animals and humans in Brazil.

Transmission of toxoplasmosis (Toxoplasma gondii) by foods

Protozoan foodborne diseases are generally underrecognized. Toxoplasma gondii is the causative agent of toxoplasmosis, one of the most prevalent parasitic infections to humans and domestic animals. The most likely source of T. gondii occurring through food is the consumption of raw or undercooked meat contaminated with tissue cysts. Sporulated T. gondii oocysts, from the feces of infected cats, present in the environment are a potential source of infection. The ingestion of water contaminated with oocysts and the eating of unwashed raw vegetables or fruits were identified as an important risk factor in most epidemiological studies. This review presents information and data to show the importance of T. gondii transmission by foods.

Prenatal education for congenital toxoplasmosis

BACKGROUND

Congenital toxoplasmosis is considered a rare but potentially severe infection. Prenatal education about congenital toxoplasmosis could be the most efficient and least harmful intervention, yet its effectiveness is uncertain.

OBJECTIVES

To assess the effects of prenatal education for preventing congenital toxoplasmosis.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (November 2007), CENTRAL (The Cochrane Library 2007, Issue 3), MEDLINE (1966 to November 2007), EMBASE (1980 to November 2007), CINAHL (1982 to November 2007), LILACS (1982 to November 2007) IMEMR (1984 to November 2007), and reference lists of relevant papers, reviews and websites.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials (RCT) of all types of prenatal education on toxoplasmosis infection during pregnancy.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed study quality and extracted data.

MAIN RESULTS

One cluster-randomized controlled trial (432 women) met the inclusion criteria. However, the overall methodological quality was poor. The authors did not report measure of association but only provided P values (P less than 0.05) for all outcomes. The authors concluded that prenatal education can effectively change pregnant women's behavior as it increased pet, personal and food hygiene. There are no randomized trials on the effect of prenatal education on congenital toxoplasmosis rate, or toxoplasmosis seroconversion rate during pregnancy, but three observational studies consistently suggest that prenatal education might have a positive impact on these outcomes.

AUTHORS' CONCLUSIONS

Even though primary prevention of congenital toxoplasmosis is considered a desirable intervention, given the lack of related risks compared to secondary and tertiary prevention, its effectiveness has not been adequately evaluated. There is very little evidence from RCTs that prenatal education is effective in reducing congenital toxoplasmosis even though evidence from observational studies suggests it is. Given the lack of good evidence supporting prenatal education for congenital toxoplasmosis prevention, further RCTs are needed to confirm any potential benefits and to further quantify the impact of different sets of educational intervention.

Predictors of retinochoroiditis in children with congenital toxoplasmosis: European, prospective cohort study

OBJECTIVE

By school age, 20% of children infected with congenital toxoplasmosis will have > or = 1 retinochoroidal lesion. We determined which children are most at risk and whether prenatal treatment reduces the risk of retinochoroiditis to help clinicians decide about treatment and follow-up.

PATIENTS AND METHODS

We prospectively studied a cohort of children with congenital toxoplasmosis identified by prenatal or neonatal screening in 6 European countries. We determined the effects of prenatal treatment and prognostic markers soon after birth on the age at first detection of retinochoroiditis.

RESULTS

Of 281 children with congenital toxoplasmosis, 50 developed ocular disease, and 17 had recurrent retinochoroiditis during a median follow-up of 4.1 years. Prenatal treatment had no significant effect on the age at first or subsequent lesions. Delayed start of postnatal treatment did not increase retinochoroiditis, but the analysis lacked power. Older gestational age at maternal seroconversion was weakly associated with a reduced risk of retinochoroiditis. The presence of nonocular clinical manifestations of congenital toxoplasmosis at birth strongly predicted retinochoroiditis. For 92% (230 of 249) of children with no retinochoroiditis detected before 4 months of age, the probability of retinochoroiditis by 4 years was low, whether clinical manifestations were present or not 8.0%.

CONCLUSIONS

Prenatal treatment did not significantly reduce the risk of retinochoroiditis in this European cohort. If children have no retinochoroiditis in early infancy, the low risk of subsequent ocular disease may not justify postnatal treatment and repeated ophthalmic assessments during childhood. Controlled trials are needed to address the lack of evidence for the effectiveness of postnatal treatment.

Toxoplasmosis

Infections with Toxoplasma gondii occur worldwide, but are especially prevalent in Europe, South America and Africa. The primary problem for the diagnosis of T. gondii infection is long-lasting IgM-antibodies, thus the presence of T. gondii-specific IgM-antibodies do not necessarily indicate an acute infection. The use of a Toxoplasma-specific IgG-avidity ratio, differentiated Western blots and two-dimensional immunoblots usually resolves diagnostic problems. There is no consensus on the best strategy to control congenital toxoplasmosis. Recent European prospective, but descriptive, studies including a meta-analysis of existing cohorts have found a surprisingly small effect on maternal-fetal transmission and clinical signs in children treated for T. gondii infection diagnosed by pre- and neonatal screening programmes. No randomised studies exist on the treatment of T. gondii infection in pregnant women and newborn children with congenital toxoplasmosis. Atovaquone is the most promising new drug available, but is not yet approved for use in pregnant women and small children.

Effectiveness of prenatal treatment for congenital toxoplasmosis: a meta-analysis of individual patients' data

BACKGROUND

Despite three decades of prenatal screening for congenital toxoplasmosis in some European countries, uncertainty remains about the effectiveness of prenatal treatment.

METHODS

We did a systematic review of cohort studies based on universal screening for congenital toxoplasmosis. We did a meta-analysis using individual patients' data to assess the effect of timing and type of prenatal treatment on mother-to-child transmission of infection and clinical manifestations before age 1 year. Analyses were adjusted for gestational age at maternal seroconversion and other covariates.

FINDINGS

We included 26 cohorts in the review. In 1438 treated mothers identified by prenatal screening, we found weak evidence that treatment started within 3 weeks of seroconversion reduced mother-to-child transmission compared with treatment started after 8 or more weeks (adjusted odds ratio [OR] 0.48, 95% CI 0.28-0.80; p=0.05). In 550 infected liveborn infants identified by prenatal or neonatal screening, we found no evidence that prenatal treatment significantly reduced the risk of clinical manifestations (adjusted OR for treated vs not treated 1.11, 95% CI 0.61-2.02). Increasing gestational age at seroconversion was strongly associated with increased risk of mother-to-child transmission (OR 1.15, 95% CI 1.12-1.17) and decreased risk of intracranial lesions (0.91, 0.87-0.95), but not with eye lesions (0.97, 0.93-1.00).

INTERPRETATION

We found weak evidence for an association between early treatment and reduced risk of congenital toxoplasmosis. Further evidence from observational studies is unlikely to change these results and would not distinguish whether the association is due to treatment or to biases caused by confounding. Only a large randomised controlled clinical trial would provide clinicians and patients with valid evidence of the potential benefit of prenatal treatment.

Prevalence and estimated incidence of Toxoplasma infection among pregnant women in Poland: a decreasing trend in the younger population

This study investigated the prevalence of specific Toxoplasma gondii IgG in pregnancy, the incidence of congenital toxoplasmosis and the prevalence trend of T. gondii infection among pregnant Polish women between 1998 and 2003. The study population comprised 4916 women who were admitted to the Polish Mother's Memorial Hospital Research Institute in Łódź. Their sera were tested for specific IgG and IgM antibodies to T. gondii, and the incidence of T. gondii infection was calculated from the increase in prevalence rates of IgG antibodies in various age groups. Specific IgG antibody was found in 41.3% (95% CI 39.9-42.7) of pregnant women, and the prevalence of IgG increased with age. The linear trend was significant (p <0.001), with an annual seroconversion rate of 0.7% (95% CI 0.004-0.010). The risk of primary infection was estimated to be 0.5% for 9 months, i.e., an incidence of 5/1000 pregnancies. Assuming a 30% maternofetal transmission rate, 1.5/1000 neonates were infected in utero. Seroprevalence during the 6-year study period decreased from 45.4% in 1998 to 39.4% in 2003, with a yearly decline in prevalence of 1.0% (p 0.02). The most important contributory factor to this decline was the group of women aged 19-29 years, among whom seroprevalence decreased significantly (p 0.007). Specific IgM was found in 244 (4.9%) women.

Chimeric antigens of Toxoplasma gondii: toward standardization of toxoplasmosis serodiagnosis using recombinant products

We have evaluated the diagnostic utility of six antigenic regions of the Toxoplasma gondii MIC2, MIC3, M2AP, GRA3, GRA7, and SAG1 gene products, assembled in recombinant chimeric antigens by genetic engineering, in order to replace the soluble, whole-cell tachyzoite extract in serological assays. Serum samples from 100 adults with acquired T. gondii infection and from 30 infants born to mothers with primary toxoplasmosis contracted during pregnancy, of whom 20 were congenitally infected, were included. Immunoglobulin G (IgG) and IgM antibodies against epitopes carried by chimeric antigens were measured by performing parallel enzyme immunoassays (recombinant enzyme-linked immunosorbent assays [Rec-ELISAs]), and the results obtained by standard commercial assays with the whole-cell Toxoplasma antigen and assays with the chimeric antigens were compared. Our results demonstrate that IgG and IgM Rec-ELISAs with individual chimeric antigens have performance characteristics comparable to those of the corresponding commercial assays. Furthermore, we show that IgM-capture assays based on chimeric antigens improve the ability to diagnose congenital toxoplasmosis postnatally compared with the ability to diagnose congenital toxoplasmosis by the use of standard assays. The use of recombinant chimeric antigens is effective in distinguishing T. gondii-infected individuals from T. gondii-uninfected individuals and shows that immunoassays based on recombinant products could provide the basis for standardized commercial tests for the serodiagnosis of toxoplasmosis.

The national neonatal screening programme for congenital toxoplasmosis in Denmark: results from the initial four years, 1999-2002

AIMS

To describe the outcome of four years' nationwide neonatal screening for congenital toxoplasmosis in liveborn newborns.

METHODS

Congenital toxoplasmosis was diagnosed if specific Toxoplasma gondii IgM antibodies were detected in eluate from the PKU Guthrie filter paper card from a child. Infants diagnosed with congenital toxoplasmosis were examined for intracranial and retinal lesions and treated for three months with sulphadiazine, pyrimethamine, and folinic acid continuously.

RESULTS

Eluates from PKU-cards from 262 912 newborns were analysed. The birth prevalence of congenital toxoplasma infection was 2.1 per 10 000 liveborns. Congenital toxoplasmosis was suspected in 96 infants and confirmed in 55. Forty seven children were examined for intracranial and retinal lesions soon after birth; 12 had clinical signs at this first examination. Of these, 5 had intracranial calcifications, 2 had retinochoroidal lesions, 4 had intracranial calcifications and retinochoroidal lesions, and 1 had hydrocephalus, intracranial calcifications, and retinochoroidal lesions. Ninety four eyes were examined soon after birth; there were central retinochoroidal lesions in 9. Two children had macular lesion of both eyes, five had macular lesions of one eye. At 1 year of age, 10/68 eyes had central lesions, and at 3 years of age, 5/32 had central lesions. Thus new retinochoroidal lesions developed in three eyes in the observation period.

CONCLUSIONS

Neonatal screening is feasible for diagnosing children with congenital toxoplasmosis at birth in low endemic areas. Retinochoroiditis with macular lesion was diagnosed in 9.6% of the eyes at birth and in 15.6% of the eyes examined at 3 years of age.

Newborn screening for congenital toxoplasmosis: feasible, but benefits are not established

Perspective on the paper by Schmidt et al (see page 661)

Treatment of infants with congenital toxoplasmosis: tolerability and plasma concentrations of sulfadiazine and pyrimethamine

The aim was to study the tolerability and plasma concentrations of pyrimethamine and sulfadiazine in children treated for congenital toxoplasmosis. Infants were diagnosed through the Danish Toxoplasma Neonatal Screening Programme, based on detection of toxoplasma-specific IgM- and/or IgA-antibodies on 3 mm blood spots collected from phenylketonuria [PKU cards (Guthrie cards)]. Toxoplasma-infected children received 3 months' continuous treatment with 50-100 mg/kg per day sulfadiazine in two separate administrations and 1 mg/kg per day pyrimethamine after a 1-day loading dose of 2 mg/kg, and folinic acid 7.5 mg was administered twice weekly. Blood cell counts and body weight were recorded during follow-up. The plasma concentrations of pyrimethamine and sulfadiazine were analysed in a subgroup of seven children, using high performance liquid chromatography with ultraviolet and mass spectrometric detection. Of 48 infants, 41 completed the treatment without change in schedule. Six infants had neutrophil counts below 0.5x10(9)/l, and one infant had an elevated bilirubin value. Twenty-nine children were tested by a series of neutrophil counts during treatment. The neutrophil count was <or=0.5x10(9)/l or lower in 4/29 (13.8%). None of the children had anaemia or thrombocytopenia. The drugs did not affect weight gain. Mean plasma drug concentrations varied between 1.3 microg/ml and 2.2 microg/ml for pyrimethamine and between 60 microg/ml and 86 microg/ml for sulfadiazine. Treatment efficacy is still a concern, since progression of eye lesions was observed in three eyes during the follow-up period. We concluded that the treatment was well tolerated in 86% (25/29) of the children. The drugs did not affect their weight gain. Drugs given in the recommended doses led to concentrations within expected therapeutic limits.

Association between prenatal treatment and clinical manifestations of congenital toxoplasmosis in infancy: a cohort study in 13 European centres

AIM

To determine the effectiveness of prenatal treatment for clinical manifestations of congenital toxoplasmosis.

METHODS

We prospectively identified 255 live-born infants with congenital toxoplasmosis using prenatal or neonatal screening. We determined the effect of prenatal treatment on the risks of intracranial or ocular lesions in infancy, accounting for gestational age at maternal seroconversion.

RESULTS

Prenatal treatment within 4 wk of seroconversion reduced the risk of intracranial lesions compared with no treatment (odds ratio, OR 0.28; 95% CI: 0.08-0.75), but there was no significant effect when initiated after 4 wk (OR 0.76; 95% CI: 0.35-1.59; overall p-value 0.19). Compared to spiramycin alone, no treatment doubled the risk of intracranial lesions (OR 2.33; 95% CI: 1.04-5.50), but the risk did not differ with pyrimethamine-sulphonamide treatment (overall p-value 0.52). There was no consistent relationship between the type or timing of treatment and the risk of ocular lesions. Gestational age at maternal seroconversion was inversely associated with the risk of intracranial but not ocular lesions.

CONCLUSION

Only early versus no prenatal treatment for intracranial lesions showed a statistically significant benefit. A large randomized controlled trial and/or meta-analysis of individual patient data from cohort studies is required to confirm these findings.

Use of recombinant antigens for early postnatal diagnosis of congenital toxoplasmosis

The main objective of this work was to improve the early serologic diagnosis of toxoplasmosis in children at risk of congenital infection by using recombinant antigens. Serum samples from 104 infants born to mothers with primary Toxoplasma gondii infection acquired during pregnancy, of which 35 were congenitally infected and 22 had clinical silent toxoplasmosis at birth, were included. Immunoglobulin M (IgM), IgG, and IgG subtype antibodies against epitopes carried by fragments of T. gondii MIC2, MIC3, MIC4, M2AP, AMA1, and SAG1 gene products were measured by performing parallel enzyme immunoassays (Rec-ELISAs). Recombinant antigens preferentially reacted with IgG antibodies from infected infants compared to uninfected subjects (P < 0.0001), indicating that sera from infected children recognized a more diverse repertoire of antigens than sera transferred over the placenta from the mothers. Using two serial samples collected within 3 months of life, it was possible to demonstrate a neosynthesis of specific anti-MIC2 and anti-SAG1 immunoglobulin G, mainly of the IgG2 subtype, in 13 out of 20 infants with congenital toxoplasmosis. IgM antibodies in 97% of infected infants reacted with at least one of the recombinant antigens, confirming the diagnosis of congenital infection as soon as 2 months after birth (P < 0.0001). The use of recombinant antigens is effective in distinguishing T. gondii-infected from uninfected infants and shows that assays based on recombinant antigens improve the diagnosis of newborns with congenital toxoplasmosis.

Biases in observational studies of the effect of prenatal treatment for congenital toxoplasmosis

The paper reviews methodological difficulties that arise when using observational studies to evaluate the effect of prenatal screening and treatment. The principle of each difficulty is described and then illustrated by a clinical example of toxoplasmosis in pregnancy and its consequences. Methods to deal with these difficulties are described. Given the limitations of existing observational studies and lack of randomised controlled trials, a systematic review of cohort studies offers the best approach for exploring potential biases.

Diagnosis and management of toxoplasmosis

This article discusses the diagnosis and management of toxoplasmosis. Congenital toxoplasmosis continues to be a tragic outcome of a preventable and treatable infection. Education of patients, physicians and health policy makers on the primary and secondary preventive measures of the disease, and their execution, will undoubtedly result in lower incidence, morbidity, and mortality rates from congenital disease due to Toxoplasma gondii.

Risk factors for Toxoplasma gondii infection in mothers of infants with congenital toxoplasmosis: Implications for prenatal management and screening

OBJECTIVE

The purpose of this study was to determine whether demographic characteristics, history of exposure to recognized transmission vehicles, or illness that was compatible with acute toxoplasmosis during gestation identified most mothers of infants with congenital toxoplasmosis.

STUDY DESIGN

Mothers of 131 infants and children who were referred to a national study of treatment for congenital toxoplasmosis were characterized demographically and questioned concerning exposure to recognized risk factors or illness.

RESULTS

No broad demographic features identified populations that were at risk. Only 48% of mothers recognized epidemiologic risk factors (direct or indirect exposure to raw/undercooked meat or to cat excrement) or gestational illnesses that were compatible with acute acquired toxoplasmosis during pregnancy.

CONCLUSION

Maternal risk factors or compatible illnesses were recognized in retrospect by fewer than one half of North American mothers of infants with toxoplasmosis. Educational programs might have prevented acquisition of Toxoplasma gondii by those mothers who had clear exposure risks. However, only systematic serologic screening of all pregnant women at prenatal visits or of all newborn infants at birth would prevent or detect a higher proportion of these congenital infections.

Severe neonatal toxoplasmosis after third trimester maternal infection

We report an unusual case of neonatal toxoplasmosis. After a late third trimester maternal infection, the infant developed severe disseminated intravascular coagulopathy with thrombocytopenia, hepatitis, jaundice and severe pneumonitis. Clinicians that manage infants with severe unexplained systemic disease should consider the possibility of congenital toxoplasmosis.

Toxoplasmosis

Toxoplasma gondii is a protozoan parasite that infects up to a third of the world's population. Infection is mainly acquired by ingestion of food or water that is contaminated with oocysts shed by cats or by eating undercooked or raw meat containing tissue cysts. Primary infection is usually subclinical but in some patients cervical lymphadenopathy or ocular disease can be present. Infection acquired during pregnancy may cause severe damage to the fetus. In immunocompromised patients, reactivation of latent disease can cause life-threatening encephalitis. Diagnosis of toxoplasmosis can be established by direct detection of the parasite or by serological techniques. The most commonly used therapeutic regimen, and probably the most effective, is the combination of pyrimethamine with sulfadiazine and folinic acid. This Seminar provides an overview and update on management of patients with acute infection, pregnant women who acquire infection during gestation, fetuses or infants who are congenitally infected, those with ocular disease, and immunocompromised individuals. Controversy about the effectiveness of primary and secondary prevention in pregnant women is discussed. Important topics of current and future research are presented.

Toxoplasmosis in pregnancy is still an open subject

OBJECTIVE

To assess the consequences of a systematic screening for toxoplasma infection in pregnant women in a potentially high risk population.

METHODS

We have investigated all consecutive women with likely toxoplasma seroconversion in a referral center setting. Data were obtained from 68 women for whom an acute infection during pregnancy was considered likely or definite. They were all treated with antibiotics in the first instance and offered, if in the first or second trimester, amniocentesis for detection of vertical transmission (PCR and IFAT). Third trimester seroconversions and positive cases after amniocentesis were offered more aggressive antibiotic treatment.

RESULTS

Five fetuses/neonates (7%) were found to be infected. Four of them were diagnosed prenatally at amniocentesis, two women decided for termination of pregnancy, two were treated and gave birth to seronegative, normally developing children. One case was found postnatally, after a third trimester conversion; this developed into hydrocephalus with neurologic impairment.

DISCUSSION

Prenatal screening and antibiotic treatment of mothers infected with toxoplasmosis showed good feasibility in our infection-susceptible population. However, there were some weak points; for example, the high number of invasive procedures and the questionable prevention of mother to child transmission in the second to third trimester.

Evaluation of a commercial IgG/IgM Western blot assay for early postnatal diagnosis of congenital toxoplasmosis

The aim of this study was to evaluate a commercial Western blot IgG/IgM assay for use in the early serological diagnosis of congenital toxoplasmosis. This assay compares the immunological profile of mother and infant and allows differentiation between passive transmitted maternal antibodies and newly synthesized antibodies of the infant within the first 3 months of life. Over a 6-year period (1995-2001), the sera from 169 mothers and their 175 offspring (6 had twins) were examined for specific anti- Toxoplasma gondii IgG, IgM and IgA antibodies with an enzyme-linked immunosorbent assay or an immunosorbent agglutination assay. All mothers had primary Toxoplasma infection during pregnancy. Serological and clinical follow-up of the infants during the first year of life confirmed 36 cases of congenital toxoplasmosis. In 139 cases, infection could be ruled out. Three hundred fifty-one paired samples from 175 mother-child pairs were tested retrospectively for IgG and IgM patterns by Toxoplasma Western blot IgG/IgM (LDBIO Diagnostics, France). The results of conventional serological analysis (immunosorbent agglutination assay or enzyme-linked immunosorbent assay) to detect IgM or IgA were compared with the results of the Toxoplasma Western blot IgG/IgM on samples obtained within the first 3 months of life. The performance of the combination of the two methods was also assessed. At birth, the sensitivity values of conventional serological analysis and the Toxoplasma Western blot were 52% and 67%, with specificity values being 99% and 96%, respectively. Combination of the Western blot and conventional serological analysis increased the sensitivity at birth to 78% and within the first 3 months of life to 85%. Overall, the combination of both methods detected 94% of congenital infections. Therefore, this commercial Western blot represents a useful tool for early postnatal diagnosis of congenital toxoplasmosis.