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

Long-term Ocular Outcomes in Congenital Toxoplasmosis Treated Perinatally

BACKGROUND

Congenital toxoplasmosis (CT) can be accompanied by serious organ manifestations, particularly retinochoroiditis, and may occur throughout life. We aimed to monitor long-term ocular prognosis in a large French cohort of patients with CT and its changes over time in the context of mandatory prenatal screening (since 1992) and incidence decrease since 2008.

METHODS

Patients with CT diagnosed between 1987 and 2021 were prospectively included and followed for up to 35 years. The effect of the period of conception on the risk of first retinochoroiditis has been tested using a flexible extension of the Cox model. Incidence rates of retinochoroiditis were estimated.

RESULTS

A total of 646 infected live born children were followed for a median of 12 years (range, 0.5-35); 187 patients (29%) had at least 1 ocular lesion (first at a median age of 5 years; range, 0-26 years) with peaks at 7 and 12 years. Early maternal infection and the presence of nonocular signs at birth were associated with a higher risk of retinochoroiditis, whereas delayed diagnosis of CT (after birth versus before or at birth) was associated with a lower risk (13% decrease for each additional month after birth; P = .01). A period effect for the risk of developing retinochoroiditis in patients born after 2008 was not detected.

CONCLUSIONS

Despite prenatal screening and prolonged perinatal treatment, retinochoroiditis is not a rare event in French patients with CT and can occur well into adulthood, with peak incidences at 7 and 12 years of age. It rarely causes severe damage but warrants regular follow-up into adulthood.

Ocular toxoplasmosis, an overview focusing on clinical aspects

Toxoplasma gondii is a widespread protozoan parasite infecting approximately one third of the world population. After proliferation of tachyzoites during the acute stage, the parasite forms tissue cysts in various anatomical sites and establishes chronic infection. Nowadays the nature of the interplay between the protozoan and its human host remains elusive. This is clearly evident in ocular toxoplasmosis, in which the parasite establishes an ambivalent relationship with the eye, manipulating the immune response and inducing variable initial lesions and further relapses. This review will focus on epidemiology and environmental, parasite and host related risk factors, clinical manifestations and laboratory findings, treatment and prophylaxis approaches in ocular toxoplasmosis. An image collection of patients referred to the Unit of Ophthalmology of Pisa's Hospital will be presented, too.

Ocular Outcome of Brazilian Patients With Congenital Toxoplasmosis

BACKGROUND

Retinochoroiditis is the most frequent manifestation of congenital toxoplasmosis. We aimed to describe the ocular outcome and factors that may influence the visual prognosis of these patients.

METHODS

Cohort of patients with confirmed congenital toxoplasmosis seen between 1996 and 2017 in Porto Alegre, southern Brazil.

RESULTS

Seventy-seven patients were included, of which 65 (85.5%) were identified by routine screening. Median age at the end of the follow-up was 10 years (minimum 2, maximum 25). Retinochoroiditis was present in 55 patients (71.4%). New retinochoroidal lesions developed after the first year of life in 77.8% of the patients who began treatment after the fourth month of life, compared with 35.2% among those treated before 4 months of life (relative risk = 0.45, 95% confidence intervals: 0.27-0.75, P = 0.02) and 33.3% among those treated before 2 months of life (relative risk = 0.42, 95% confidence intervals: 0.25-0.72, P = 0.01). There was a peak incidence of new retinochoroidal lesions between 4 and 5 years and another peak between 9 and 14 years, the latter only among girls. Thirty-four patients with retinochoroiditis were followed up for 10 years or more, and the school performance was appropriate in 28 (82.4%).

CONCLUSIONS

The high incidence of new retinochoroidal lesions during the follow-up period indicates the importance of long-term follow-up of patients with congenital toxoplasmosis. Initiating treatment within the first 4 months of life, especially within the first 2 months, was a protective factor against the later development of retinochoroiditis. Despite the usual favorable prognosis, the high morbidity of congenital toxoplasmosis in Brazil was confirmed.

Prevention and mitigation of congenital toxoplasmosis. Economic costs and benefits in diverse settings

Congenital toxoplasmosis (CT), the result of a primary infection of pregnant women with Toxoplasma gondii which was transmitted to the fetus, may result in mild to deep injuries occurring in the newborn or later in its development or in adolescence. The visual and cognitive impairment that can result imposes substantial economic costs on the individual and society. Numerous observational studies favor the conclusion that, with preventive measures currently available, it is possible to reduce the incidence of infections in pregnant women, the incidence of fetal infection by preventing transplacental transmission, and the gravity of injury in infected newborns. Treatment of infected newborns can also reduce the severity of consequences and the frequency of their occurrence later in life. Prevention programs, however, are applied in only a few countries; in most countries implementation of a national prevention program has not been considered or has been thought to be too expensive. This article lists the methods of prevention of CT and describes existing national prevention programs in France and Austria. It analyzes the economic costs and benefits of maternal screening for CT prevention and mitigation for society and for health systems. The economic feasibility of implementing national screening in low-prevalence, high-cost countries is illustrated with the example of the United States. New diagnostic tools are discussed and the implication of lower costs is considered, for countries with well-established screening programs as well as those with inadequate prenatal care networks.

Ophthalmic outcomes of congenital toxoplasmosis followed until adolescence

BACKGROUND

Congenital toxoplasmosis (CT) can elicit severe damage to several organs, especially the eye, and may be manifested at birth or later. We assessed the long-term ocular prognosis in a cohort of congenitally infected children treated according to a standardized protocol and monitored for up to 22 years.

METHODS

This prospective study included confirmed cases of CT, which were identified by obligatory antenatal screening at the Lyon (France) reference center between 1987 and 2008. Data obtained through ocular examinations were recorded on a standardized form and confirmed by an independent external committee. Risk factors for retinochoroiditis were identified by using a multivariable Cox model and a flexible model that accounted for changes in the factor effects during follow-up.

RESULTS

A total of 477 of 485 infected live-born children were followed for a median of 10.5 years (75th percentile: 15.0 years). During the follow-up, 142 patients (29.8%) manifested at least 1 ocular lesion. Lesions were unilateral in 98 individuals (69.0%) and caused no vision loss in 80.6%. Lesions were first manifested at a median age of 3.1 (0.0-20.7) years. In 48 (33.8%) of the children, recurrences or new ocular lesions occurred up to 12 years after the appearance of the first lesion. Early maternal infection and confirmation of CT in children, prematurity, and nonocular CT lesions at baseline were associated with a higher risk of retinochoroiditis.

CONCLUSIONS

Although the consequences of CT are rarely severe in treated children, regular postnatal monitoring is nevertheless justified because of the lifelong persisting risk of new ocular manifestations.

Congenital toxoplasmosis and prenatal care state programs

BACKGROUND

Control programs have been executed in an attempt to reduce vertical transmission and the severity of congenital infection in regions with a high incidence of toxoplasmosis in pregnant women. We aimed to evaluate whether treatment of pregnant women with spiramycin associated with a lack of monitoring for toxoplasmosis seroconversion affects the prognosis of patients.

METHODS

We performed a prospective cohort study with 246 newborns (NB) at risk for congenital toxoplasmosis in Goiânia (Brazil) between October 2003 and October 2011. We analyzed the efficacy of maternal treatment with spiramycin.

RESULTS

A total of 40.7% (66/162) of the neonates were born seriously infected. Vertical transmission associated with reactivation during pregnancy occurred in 5.5% (9/162) of the NB, with one showing severe infection (systemic). The presence of specific immunoglobulins (fetal IgM and NB IgA) suggested the worst prognosis. Treatment of pregnant women by spiramycin resulted in reduced vertical transmission. When infected pregnant women did not undergo proper treatment, the risk of severe infection (neural-optical) in NB was significantly increased. Fetal IgM was associated with ocular impairment in 48.0% (12/25) of the fetuses and neonatal IgA-specific was related to the neuro-ophthalmologic and systemic forms of the disease. When acute toxoplasmosis was identified in the postpartum period, a lack of monitoring of seronegative pregnant women resulted in a higher risk of severe congenital infection.

CONCLUSION

Treatment of pregnant women with spiramycin reduces the possibility of transmission of infection to the fetus. However, a lack of proper treatment is associated with the onset of the neural-optical form of congenital infection. Primary preventive measures should be increased for all pregnant women during the prenatal period and secondary prophylaxis through surveillance of seroconversion in seronegative pregnant woman should be introduced to reduce the severity of congenital infection in the environment.

Estimates of the burden of foodborne illness in Canada for 30 specified pathogens and unspecified agents, circa 2006

Estimates of foodborne illness are important for setting food safety priorities and making public health policies. The objective of this analysis is to estimate domestically acquired, foodborne illness in Canada, while identifying data gaps and areas for further research. Estimates of illness due to 30 pathogens and unspecified agents were based on data from the 2000-2010 time period from Canadian surveillance systems, relevant international literature, and the Canadian census population for 2006. The modeling approach required accounting for under-reporting and underdiagnosis and to estimate the proportion of illness domestically acquired and through foodborne transmission. To account for uncertainty, Monte Carlo simulations were performed to generate a mean estimate and 90% credible interval. It is estimated that each year there are 1.6 million (1.2-2.0 million) and 2.4 million (1.8-3.0 million) episodes of domestically acquired foodborne illness related to 30 known pathogens and unspecified agents, respectively, for a total estimate of 4.0 million (3.1-5.0 million) episodes of domestically acquired foodborne illness in Canada. Norovirus, Clostridium perfringens, Campylobacter spp., and nontyphoidal Salmonella spp. are the leading pathogens and account for approximately 90% of the pathogen-specific total. Approximately one in eight Canadians experience an episode of domestically acquired foodborne illness each year in Canada. These estimates cannot be compared with prior crude estimates in Canada to assess illness trends as different methodologies were used.

A dedicated surveillance network for congenital toxoplasmosis in Greece, 2006-2009: assessment of the results

BACKGROUND

Toxoplasmosis is caused by infection with the protozoan parasite Toxoplasma gondii. Acute infections in pregnant women may be transmitted to the fetus and cause severe illness. The purpose of this study was to establish a dedicated surveillance network (DSN) for congenital toxoplasmosis (CT) in Greece, in order to assess the birth prevalence of CT.

METHODS

A DSN of thirty clinicians was established for reporting CT cases from hospitals throughout Greece. The clinicians were selected on the basis that there was a high possibility the suspected cases would be referred to them from district hospitals or private clinics. Suspected cases of CT were reported on a monthly basis with a zero reporting card during a surveillance period from April 2006 to December 2009. A questionnaire was sent for any suspected case to record information including demographic parameters, clinical signs and symptoms and laboratory results. Serological and molecular confirmation of cases was performed by the Pasteur Hellenic Institute. All newborns suspected of CT received treatment and were serologically and clinically followed up for one year.

RESULTS

The monthly response rate reached 100%, although only after reminders sent to 65% of the participant physicians. Sixty-three suspected CT cases were recorded by the DSN during the study period including fourteen confirmed and seven probable cases. Ten cases (47.6%) presented with symptoms at birth. Chorioretinitis was the most prominent manifestation, occurring in five symptomatic CT cases (50%). No other symptoms appeared by the end of the one year clinical follow up. No case was recorded by the existing surveillance system of the Hellenic Center of Disease Control and Prevention (HCDCP) during the same time period. Birth prevalence was estimated at 0.45, 0.51 and 0.51 per 10,000 births for 2007, 2008 and 2009 respectively. The incidence rate of symptomatic CT at birth was estimated at 0.10 cases per 10,000 births per year in Greece (for the period 2007-2009).

CONCLUSION

The DSN for CT proved to be more sensitive than the classical notification system, easy in application and very efficient in reporting rare diseases such as CT. Similar DSNs could be used to provide useful information on other rare diseases.

Long-term ocular outcome in congenital toxoplasmosis: a prospective cohort of treated children

OBJECTIVES

Congenital toxoplasmosis remains a public health problem throughout the world. Long-term longitudinal studies are still needed to argument controversial screening and treatment strategies and to enable to accurately counsel parents.

METHODS

We conducted a prospective cohort study over 16 years in Marseilles, France. Seronegative pregnant women underwent monthly serological testing. Children were treated antenatally with rovamycine as soon as maternal infection was detected and with pyrimethamine and sulfadoxine in case of positive Toxoplasma PCR on amniotic fluid. Postnatal treatment with pyrimethamine and sulfadoxine was systematically prescribed for one year and possibly continued at the physician discretion.

RESULTS

127 children were included. 24 children (18.9%) presented ocular lesions causing visual impairment in eight cases. Eleven children (8.7%) presented with ocular lesions at birth, mostly macular. Sixteen children (12.6%) developed ocular lesions during follow-up, mostly peripheral. The first ocular lesion could occur as late as 12 years after birth. No significant risk factor of chorioretinitis was identified including gestational age at infection, type of antenatal treatment and shorter postnatal treatment.

CONCLUSIONS

These results confirm the overall good prognosis of congenital toxoplasmosis in Europe but highlight though a low risk of late ocular manifestation. Chorioretinitis affected 18.9% of children suffering from congenital toxoplasmosis despite antenatal and neonatal screening associated with early treatment. Long-standing follow-up is needed because first lesion can occur as late as 12 years after birth. Late lesions were less often macular but nevertheless caused sometimes visual impairment.

Clinical manifestations of ocular toxoplasmosis

Clinical manifestations of ocular toxoplasmosis are reviewed. Findings of congenital and acute acquired ocular toxoplasmosis include retinal scars, white-appearing lesions in the active phase often associated with vitritis. Complications can include fibrous bands, secondary serous or rhegmatogenous retinal detachments, optic neuritis and neuropathy, cataracts, increased intraocular pressure during active infection, and choroidal neovascular membranes. Recurrences in untreated congenital toxoplasmosis occur in teenage years. Manifestations at birth are less severe, and recurrences are fewer in those who were treated promptly early in the course of their disease in utero and in the first year of life. Severe retinal involvement is common at diagnosis of symptomatic congenital toxoplasmosis in the United States and Brazil. Acute acquired infections also may be complicated by toxoplasmic retinochoroiditis, with recurrences most common close to the time of acquisition. Suppressive treatment can reduce recurrent disease.

Long-term outcome of children with congenital toxoplasmosis

OBJECTIVE

Maternal toxoplasmosis infection acquired during pregnancy carries significant risk of fetal damage. We aimed to assess the long-term outcome of children and young adults with congenital toxoplasmosis diagnosed and treated in utero.

STUDY DESIGN

This was a 20 year prospective study (1985-2005). All mothers received spiramycin, alone or associated with pyrimethamine-sulfadoxine, and underwent amniocentesis and monthly ultrasound screening. Infected children were followed every 3-6 months.

RESULTS

Of 666 liveborn children (676 mothers), 112 (17%) had congenital toxoplasmosis. Among these, 107 were followed up for 12-250 months: 79 were asymptomatic (74%) and 28 had chorioretinitis (26%). Only 1 child had a serious neurological involvement.

CONCLUSION

The percentage of chorioretinitis in treated children depends on length of follow-up, but this complication occurs mainly before the age of 5 years and almost always before the age of 10 years. Visual impairment was infrequently severe, and outcome appears consistently good. Long-term follow-up is recommended to monitor ocular and neurological prognosis, whatever the practical difficulties.

[Toxoplasmosis and pregnancy]

Toxoplasmosis is the most common etiology of posterior uveitis. Toxoplasma gondii infection during pregnancy means either primary infection and risk of congenital toxoplasmosis or acute retinochoroiditis in a pregnant woman (risk of transmission, severity of injuries, therapeutics). Ingestion or manipulation of raw or undercooked meat is responsible for most contaminations (one- to two-thirds) in pregnant women. Toxoplasmosis seroprevalence is high in Europe, up to 54 % in southern European countries. Primary prevention advice is proposed to immunocompetent pregnant women who are seronegative for toxoplasmosis. The risk of transplacental transmission congenital toxoplasmosis during pregnancy is analyzed. The ocular lesions include retinochoroiditis and a number of other lesions. The departments of ophthalmology and of parasitology of Croix-Rousse University Hospital (Hospices Civils de Lyon) is currently following one of the largest cohorts of children infected with T. gondii (430 children alive in 2005). Our overall transmission rate during primary infection was 30 %. Retinochoroiditis incidence was 24 % in our prospective cohort. During follow-up, recurrences appeared in 29 % of cases. Acute toxoplasmic retinochoroiditis in pregnancy could be a risk of transplacental transmission due to potential parasitemia. Practices in cases of suspected or proved congenital infection are discussed. The antiparasitic drugs authorized during pregnancy are azithromycin and pyrimethamine. Azithromycin can be used alone but an association with pyrimethamine during the second trimester is useful in case of macular threat.

Options for clinical trials of pre and post-natal treatments for congenital toxoplasmosis

Clinical trials comparing different drug regimens and strategies for the treatment of congenital toxoplasmosis and its clinical manifestations in the liveborn child in different clinical settings should aim at formally evaluating the net benefit of existing treatments and at developing new therapeutic options. Currently, there is no ideal drug for congenital toxoplasmosis; future research should focus on the screening of new active drugs and on their pre-clinical and early clinical development, with a focus on pharmacokinetic/dynamic studies and teratogenicity. For the prenatal treatment of congenital toxoplasmosis, a trial comparing spiramycine to pyrimethamine-sulphadiazine and placebo would allow a formal estimation of the effect of both drugs in infected pregnant women. In newborn children, the net benefit of pyrimethamine-sulphadiazine should also be formally assessed. These trials will be implemented in settings where prenatal screening for Toxoplasma gondii is currently implemented. Trials should be carefully designed to allow for translation to other settings and modelling tools like cost-effectiveness analysis should be used to provide clinicians and founders with the best available evidence to establish recommendations.

Congenital toxoplasmosis and DALYs in the Netherlands

The calculation of disability-adjusted life years (DALYs) enables public health policy makers to compare the burden of disease of a specific disease with that of other (infectious) diseases. The incidence of a disease is important for the calculation of DALYs. To estimate the incidence of congenital toxoplasmosis (CT), a random sample of 10,008 dried blood spot filter paper cards from babies born in 2006 in the Netherlands were tested for Toxoplasma gondii-specific IgM antibodies. Eighteen samples were confirmed as positive for IgM, resulting in an observed birth incidence of CT of 1.8 cases per 1,000 live-born children in 2006 and an adjusted incidence of 2.0 cases per 1,000. This means that 388 infected children were born in 2006. The most likely burden of disease is estimated to be 2,300 DALYs (range 820-6,710 DALYs). In the previous calculations, using data from a regional study from 1987, this estimate was 620 DALYs (range 220-1,900 DALYs). The incidence of CT in the Netherlands is much higher than previously reported; it is 10 times higher than in Denmark and 20 times higher than in Ireland, based on estimates obtained using the same methods. There is no screening program in the Netherlands; most children will be born asymptomatic and therefore will not be detected or treated.

Why prevent, diagnose and treat congenital toxoplasmosis?

Evidence that prevention, diagnosis and treatment of toxoplasmosis is beneficial developed as follows: anti-parasitic agents abrogate Toxoplasma gondii tachyzoite growth, preventing destruction of infected, cultured, mammalian cells and cure active infections in experimental animals, including primates. They treat active infections in persons who are immune-compromised, limit destruction of retina by replicating parasites and thereby treat ocular toxoplasmosis and treat active infection in the fetus and infant. Outcomes of untreated congenital toxoplasmosis include adverse ocular and neurologic sequelae described in different countries and decades. Better outcomes are associated with treatment of infected infants throughout their first year of life. Shorter intervals between diagnosis and treatment in utero improve outcomes. A French approach for diagnosis and treatment of congenital toxoplasmosis in the fetus and infant can prevent toxoplasmosis and limit adverse sequelae. In addition, new data demonstrate that this French approach results in favorable outcomes with some early gestation infections. A standardized approach to diagnosis and treatment during gestation has not yet been applied generally in the USA. Nonetheless, a small, similar experience confirms that this French approach is feasible, safe, and results in favorable outcomes in the National Collaborative Chicago-based Congenital Toxoplasmosis Study cohort. Prompt diagnosis, prevention and treatment reduce adverse sequelae of congenital toxoplasmosis.

Longitudinal study of new eye lesions in children with toxoplasmosis who were not treated during the first year of life

PURPOSE

To determine the incidence of new chorioretinal lesions in children with toxoplasmosis diagnosed after, and therefore not treated during, their first year.

DESIGN

Prospective longitudinal cohort study.

METHODS

Thirty-eight children were evaluated in Chicago between 1981 and 2005 for new chorioretinal lesions. Thirty-eight children and mothers had serum IgG antibody to Toxoplasma gondii.

RESULTS

Twenty-eight of 38 children had one of the following: diagnosis with serum antibody to T. gondii indicative of chronic infection at age 24 months, central nervous system calcifications, hydrocephalus, illness compatible with congenital toxoplasmosis perinatally but not diagnosed at that time. Twenty-five returned for follow-up during 1981 to 2005. Their mean (range) age at last exam was 10.9 +/- 5.7 (range, 3.5 to 27.2) years and mean follow-up was 5.7 +/- 2.9 years. Eighteen (72%) children developed at least one new lesion. Thirteen (52%) had new central lesions, 11 (44%) had new peripheral lesions, and six (24%) had both. Thirteen (52%) had new lesions diagnosed at age > or =10 years. New lesions were found at more than one visit in four (22%), and bilateral new lesions developed in seven (39%) of 18 children who developed new lesions. Of 10 additional children with eye findings and serologic tests indicative of chronic infection, six returned for follow-up, four (67%) developing new lesions at > or =10 years of age.

CONCLUSIONS

More than 70% developed new chorioretinal lesions. New lesions were commonly diagnosed after the first decade of life.

Ocular sequelae of congenital toxoplasmosis in Brazil compared with Europe

Background

Toxoplasmic retinochoroiditis appears to be more severe in Brazil, where it is a leading cause of blindness, than in Europe, but direct comparisons are lacking. Evidence is accumulating that more virulent genotypes of Toxoplasma gondii predominate in South America.

Methods

We compared prospective cohorts of children with congenital toxoplasmosis identified by universal neonatal screening in Brazil and neonatal or prenatal screening in Europe between 1992 and 2003, using the same protocol in both continents.

Results

Three hundred and eleven (311) children had congenital toxoplasmosis: 30 in Brazil and 281 in Europe, where 71 were identified by neonatal screening. Median follow up was 4.1 years in Europe and 3.7 years in Brazil. Relatively more children had retinochoroiditis during the first year in Brazil than in Europe (15/30; 50% versus 29/281; 10%) and the risk of lesions by 4 years of age was much higher: the hazard ratio for Brazil versus Europe was 5.36 (95%CI: 3.17, 9.08). Children in Brazil had larger lesions, which were more likely to be multiple and to affect the posterior pole (p<0.0001). In Brazil, visual impairment (<6/12 Snellen) was predicted for most affected eyes (87%, 27/31), but not in Europe (29%; 20/69, p<0.0001). The size of newly detected lesions decreased with age (p = 0.0007).

Conclusions

T. gondii causes more severe ocular disease in congenitally infected children in Brazil compared with Europe. The marked differences in the frequency, size and multiplicity of retinochoroidal lesions may be due to infection with more virulent genotypes of the parasite that predominate in Brazil but are rarely found in Europe.

Toxoplasma gondii is found throughout the world and is the most common parasitic infection in humans. Infection can cause inflammatory lesions at the back of the eye, which sometimes affect vision. These complications appear to be more common and more severe when people acquire infection in Brazil than in Europe or North America, but there have been no direct comparisons of patients identified and followed up in the same way. In this report, we compare children with congenital toxoplasmosis diagnosed at birth by universal screening in Europe and Brazil and followed up until the age of 4. We found that Brazilian children had a 5 times higher risk than European children of developing eye lesions and their lesions were larger, more numerous and more likely to affect the part of the area of the retina responsible for central vision. Two-thirds of Brazilian children infected with congenital toxoplasmosis had eye lesions by 4 years of age compared with 1 in 6 in Europe. These stark differences are likely to be due to the predominance of more virulent genotypes of the parasite in Brazil, which are rarely found in Europe.

Genetic and epigenetic factors at COL2A1 and ABCA4 influence clinical outcome in congenital toxoplasmosis

Background

Primary Toxoplasma gondii infection during pregnancy can be transmitted to the fetus. At birth, infected infants may have intracranial calcification, hydrocephalus, and retinochoroiditis, and new ocular lesions can occur at any age after birth. Not all children who acquire infection in utero develop these clinical signs of disease. Whilst severity of disease is influenced by trimester in which infection is acquired by the mother, other factors including genetic predisposition may contribute.

Methods and Findings

In 457 mother-child pairs from Europe, and 149 child/parent trios from North America, we show that ocular and brain disease in congenital toxoplasmosis associate with polymorphisms in ABCA4 encoding ATP-binding cassette transporter, subfamily A, member 4. Polymorphisms at COL2A1 encoding type II collagen associate only with ocular disease. Both loci showed unusual inheritance patterns for the disease allele when comparing outcomes in heterozygous affected children with outcomes in affected children of heterozygous mothers. Modeling suggested either an effect of mother's genotype, or parent-of-origin effects. Experimental studies showed that both ABCA4 and COL2A1 show isoform-specific epigenetic modifications consistent with imprinting.

Conclusions

These associations between clinical outcomes of congenital toxoplasmosis and polymorphisms at ABCA4 and COL2A1 provide novel insight into the molecular pathways that can be affected by congenital infection with this parasite.

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.

Survey of European programmes for the epidemiological surveillance of congenital toxoplasmosis

The objective of this investigation was to describe systems for the epidemiological surveillance of congenital toxoplasmosis implemented in European countries. In September 2004, a questionnaire, adapted from the evaluation criteria published by the United States Centers for Disease Control and Prevention, was sent to a panel of national correspondents in 35 countries in the European geographical area with knowledge of the epidemiological surveillance systems implemented in their countries. Where necessary, we updated the information until July 2007. Responses were received from 28 countries. Some 16 countries reported routine surveillance for toxoplasmosis. In 12 countries (Bulgaria, Cyprus, Czech Republic, England and Wales, Estonia, Ireland, Latvia, Lithuania, Malta, Poland, Scotland and Slovakia), surveillance was designed to detect only symptomatic toxoplasmosis, whether congenital or not. Four countries reported surveillance of congenital toxoplasmosis, on a regional basis in Italy and on a national basis in Denmark, France and Germany. In conclusion, epidemiological surveillance of congenital toxoplasmosis needs to be improved in order to determine the true burden of disease and to assess the effectiveness of and the need for existing prevention programmes.

Risk factors for retinochoroiditis during the first 2 years of life in infants with treated congenital toxoplasmosis

BACKGROUND

Retinochoroiditis is the main complication of congenital toxoplasmosis. Its risk factors have rarely been investigated and were the object of this study.

METHODS

A retrospective study was conducted on 300 infants with congenital toxoplasmosis born between July 1, 1996 and December 31, 2002 and treated with pyrimethamine and sulfonamide for at least 12 months. Results of eye tests were collected up to 24 months. Risk factors associated with first retinochoroiditis were identified by univariate then multivariate analyses (Cox model).

RESULTS

One hundred forty-nine boys and 151 girls were included. Maternal infection dated from the first trimester in 34 cases, the second in 97 cases, and the last in 169 cases. At birth, 22 infants had cerebral calcifications. During the first 2 years of life, first retinochoroiditis was diagnosed in 36 infants (12%). In multivariate analysis, 3 factors were significantly associated with first retinochoroiditis before the age of 2 years: a delay of >8 weeks between maternal seroconversion and first treatment [hazard ratio, 2.54; 95% confidence interval (CI), 1.14-5.65], female gender (hazard ratio, 2.02; 95% CI, 1.01-4.1), and cerebral calcifications at birth (hazard ratio, 4.3; 95% CI, 1.9-10). There was no correlation between gestational age at the time of maternal infection and risk for retinochoroiditis.

CONCLUSIONS

A delay of >8 weeks between maternal seroconversion and the beginning of treatment, female gender, and especially cerebral calcifications are risk factors for retinochoroiditis during the first 2 years of life in infants treated for congenital toxoplasmosis.

Risk of visual impairment in children with congenital toxoplasmic retinochoroiditis

PURPOSE

Reliable information is needed to counsel parents of children with congenital toxoplasmosis regarding the long-term risk of visual impairment resulting from ocular toxoplasmosis.

DESIGN

Prospective cohort study of children with congenital toxoplasmosis identified by prenatal or neonatal screening.

METHODS

After three years of age, ophthalmologists reported the site of retinochoroidal lesions and visual acuity and parents reported visual impairment. An ophthalmologist predicted the child's vision based on the last retinal diagram. Selection biases were minimized by prospective enrollment and data collection, high rates of follow-up, and exclusion of referred cases.

RESULTS

Two hundred and eighty-one of 284 infected children who underwent ophthalmic examinations were followed up to a median age of 4.8 years. One in six children (49/281; 17%) had at least one retinochoroidal lesion, two-thirds of whom (32/49; 65%) had a lesion at the posterior pole. In children with retinochoroiditis who had visual acuity measured after 3 years of age, 94% (31/33) had normal vision in the best eye (6/12 Snellen or better), as did 91% of those with a posterior pole lesion (21/23). Analyses based on affected eyes showed that 42% (29/69) had a posterior pole lesion, of which just more than half (15/29, 52%) had normal vision, as did 84% (16/19) of eyes with a peripheral lesion alone. Vision predicted by the ophthalmologist was moderately sensitive (59%) but overestimated impairment associated with posterior pole lesions. Of 44 children with information on acuity, four (9%) had bilateral visual impairment worse than 6/12 Snellen.

CONCLUSIONS

Severe bilateral impairment occurred in 9% of children with congenital toxoplasmic retinochoroiditis. Half the children with a posterior pole lesion and one in six of those with peripheral lesions alone were visually impaired in the affected eye.

Longitudinal study of new eye lesions in treated congenital toxoplasmosis

OBJECTIVE

To determine the incidence of new chorioretinal lesions in patients with congenital toxoplasmosis who were treated throughout their first year of life.

DESIGN

Prospective longitudinal observation of a cohort.

PARTICIPANTS

One hundred thirty-two children were studied as part of the longitudinal observation.

METHODS

One hundred thirty-two children were treated during their first year of life with pyrimethamine, sulfadiazine, and leucovorin. They had eye examinations at prespecified intervals.

MAIN OUTCOME MEASURES

New chorioretinal lesions on fundus examination and fundus photographs.

RESULTS

The mean age (+/- standard deviation) is 10.8+/-5.1 years (range, 0.2-23). One hundred eight children have been evaluated for new chorioretinal lesions. Thirty-four (31%; 95% confidence interval, 23%-41%) of 108 children developed at least one chorioretinal lesion that was previously undetected. These occurred at varying times during their follow-up course. Fifteen children (14%) developed new central lesions, and 27 (25%) had newly detected lesions peripherally. Ten (9%) had more than one occurrence of new lesions developing, and 13 (12%) had new lesions in both eyes. Of those who developed new lesions, 14 children (41%) did so at age 10 or later.

CONCLUSION

New central chorioretinal lesions are uncommon in children with congenital toxoplasmosis who are treated during their first year of life. This finding contrasts markedly with earlier reports in the literature for untreated children or those treated for only 1 month near birth, in whom new lesions were much more prevalent (>/=82%). Our observation that 14 (41%) of the 34 children with new chorioretinal lesions had occurrences when they were 10 years or older indicates that long-term follow-up into the second decade of life is important in assessing the efficacy of treating toxoplasmosis during infancy.

Disease burden of congenital toxoplasmosis

Although the outcomes of toxoplasmosis have been well documented, an integrated estimate of the impact of this infection on the health status of the population is not available. "Disability-adjusted life years" are the sum of years of life lost and years lived with disability, weighted for the severity of the illness. The estimated disease burden of congenital toxoplasmosis in The Netherlands is 620 (range, 220-1900) disability-adjusted life years per year, which is similar to that for salmonellosis and is mainly caused by fetal loss and chorioretinitis. However, there is considerable uncertainty in this estimate. Scenario analysis indicates that the true burden may be underestimated. In other countries, the disease burden is expected to vary with the incidence of congenital infection, but it may also depend on the health care system. In countries that actively screen for toxoplasmosis, such as France, there may be a lower burden of morbidity but a higher burden of mortality.

Toxoplasmic retinochoroiditis presenting in childhood: clinical findings in a UK survey

AIM

To compare the clinical findings in children with symptomatic toxoplasmic ocular lesions attributable to infection acquired before or after birth.

METHODS

Cases were prospectively ascertained for 24 months through national surveillance units and reference laboratories in the British Isles. Age and presenting symptoms, site of lesion and visual impairment in children who were classified as acquiring infection either before or after birth on the basis of clinical and serological findings were compared.

RESULTS

31 children had toxoplasmic retinochoroiditis, 15 had congenital infection and all but three of these presented before the age of 4 years. The remaining 16 children acquired toxoplasmosis postnatally, and 14 of 16 presented after the age of 10 years. A further four children had retinochoroiditis due to other causes. The presence of bilateral, multiple or posterior pole lesions did not distinguish between the two groups, but most children (16/19; 84%) presenting with acute ocular symptoms had postnatally acquired infection. Unilateral visual impairment (Snellen < or =6/18) was equally prevalent in the two groups (4/9 before birth v 7/16 after birth; p>0.5). Only two children had bilateral visual impairment, both of whom had congenital infection. No child was blind.

CONCLUSIONS

About 50% of children with ocular lesions due to toxoplasmosis had postnatal infection. Retinochoroidal lesions due to infection before and after birth were indistinguishable. The prognosis for bilateral visual function was good, regardless of when infection was acquired.

Modeling Human Metabolism of Benzene Following Occupational and Environmental Exposures

We used natural spline (NS) models to investigate nonlinear relationships between levels of benzene metabolites (E,E-muconic acid, S-phenylmercapturic acid, phenol, hydroquinone, and catechol) and benzene exposure among 386 exposed and control workers in Tianjin, China. After adjusting for background levels (estimated from the 60 control subjects with the lowest benzene exposures), expected mean trends of all metabolite levels increased with benzene air concentrations from 0.03 to 88.9 ppm. Molar fractions for phenol, hydroquinone, and E,E-muconic acid changed continuously with increasing air concentrations, suggesting that competing CYP-mediated metabolic pathways favored E,E-muconic acid and hydroquinone below 20 ppm and favored phenol above 20 ppm. Mean trends of dose-specific levels (micromol/L/ppm benzene) of E,E-muconic acid, phenol, hydroquinone, and catechol all decreased with increasing benzene exposure, with an overall 9-fold reduction of total metabolites. Surprisingly, about 90% of the reductions in dose-specific levels occurred below about 3 ppm for each major metabolite. Using generalized linear models with NS-smoothing functions (GLM + NS models), we detected significant effects upon metabolite levels of gender, age, and smoking status. Metabolite levels were about 20% higher in females and decreased between 1% and 2% per year of life. In addition, levels of hydroquinone and catechol were greater in smoking subjects. Overall, our results indicate that benzene metabolism is highly nonlinear with increasing benzene exposure above 0.03 ppm, and that current human toxicokinetic models do not accurately predict benzene metabolism below 3 ppm. Our results also suggest that GLM + NS models are ideal for evaluating nonlinear relationships between environmental exposures and levels of human biomarkers.

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

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

Symptomatic toxoplasma infection due to congenital and postnatally acquired infection

AIMS

To determine the incidence and severity of symptomatic toxoplasma infection presenting during childhood due to congenital or postnatally acquired infection.

METHODS

Between 2002 and 2004, newly diagnosed children (<16 years) with signs or symptoms of congenital or ocular toxoplasmosis were reported by clinicians to the British Paediatric and Ophthalmic Surveillance Units or by toxoplasma referral laboratories. Confirmed cases were estimated to have a greater than 50% probability of congenital and/or ocular toxoplasmosis, based on clinical and serological findings.

RESULTS

Thirty eight children had confirmed toxoplasma infection. Twenty two (58%) were classified with congenital infection (cumulative incidence for England and Wales 1.62[corrected]/100,000 live births; 95% CI 0.85[corrected] to 2.83[corrected]), of whom 2 (9%) were stillborn, 7 (32%) live births had intracranial abnormalities and/or developmental delay (5 of whom had retinochoroiditis), and 10 (45%) had retinochoroiditis with no other abnormalities reported. A further 16 (42%) children were classified as infected after birth; all had retinochoroiditis.

CONCLUSIONS

The low burden of symptomatic congenital toxoplasmosis combined with the lack of evidence of an effective treatment support current policy not to offer prenatal or neonatal screening for toxoplasma infection. Primary prevention strategies need to address acquisition of infection in childhood which accounts for half the ocular disease due to toxoplasma infection in children in the UK and Ireland.

Outcome of treatment for congenital toxoplasmosis, 1981-2004: the National Collaborative Chicago-Based, Congenital Toxoplasmosis Study

BACKGROUND

Without treatment, congenital toxoplasmosis has recurrent, recrudescent, adverse outcomes. Long-term follow-up of infants with congenital toxoplasmosis treated throughout their first year of life with pyrimethamine and sulfadiazine has not been reported.

METHODS

Between 1981 and 2004, one hundred twenty infants (current mean age +/- standard deviation, 10.5 +/- 4.8 years) with congenital toxoplasmosis were treated with 1 of 2 doses of pyrimethamine plus sulfadiazine; therapy was initiated shortly after birth and continued for 12 months. Children who received treatment were evaluated at birth and at predetermined intervals; the focus of the evaluations was on prespecified end points: motor abnormalities, cognitive outcome, vision impairment, formation of new eye lesions, and hearing loss.

RESULTS

Treatment of infants without substantial neurologic disease at birth with pyrimethamine and sulfadiazine for 1 year resulted in normal cognitive, neurologic, and auditory outcomes for all patients. Treatment of infants who had moderate or severe neurologic disease (as defined in this article in the Treatments subsection of Methods) at birth resulted in normal neurologic and/or cognitive outcomes for >72% of the patients, and none had sensorineural hearing loss. Ninety-one percent of children without substantial neurologic disease and 64% of those with moderate or severe neurologic disease at birth did not develop new eye lesions. Almost all of these outcomes are markedly better than outcomes reported for children who were untreated or treated for 1 month in earlier decades (P<.01 to P<.001). Sex and severity of disease were comparable in our 2 treatment groups, and no significant differences in efficacy or toxicity were noted between the 2 treatment groups (P > .05).

CONCLUSIONS

Although not all children did well with treatment, the favorable outcomes we noted indicate the importance of diagnosis and treatment of infants with congenital toxoplasmosis.

Methods to estimate the optimal threshold for normally or log-normally distributed biological tests

Putting a screening or a diagnostic test into everyday use requires the determination of its threshold. The authors present methods that yield a point and an interval estimation of the threshold that maximize the population utility whenever the test results are normally or log-normally distributed among healthy and among diseased subjects, with equal variances. These methods were assessed for bias, coverage probability, coverage symmetry, and confidence-interval width using simulation. They proved to be asymptotically nonbiased and to have a satisfactory coverage probability whenever the sample sizes of the healthy and the diseased subjects are equal to or greater than 50. The methods were next applied to determine an optimal threshold for the antibody load used to diagnose congenital toxoplasmosis at birth. The methods are easy to implement and impose few constraints; however, the sample sizes should be carefully determined according to the required accuracy.

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.

Association between congenital toxoplasmosis and parent-reported developmental outcomes, concerns, and impairments, in 3 year old children

Background

Information is lacking on the effects of congenital toxoplasmosis on development, behavior, and impairment in later childhood, as well as on parental concerns and anxiety. This information is important for counselling parents about the prognosis for an infected child and for policy decisions on screening.

Methods

We prospectively studied a cohort of children identified by screening for toxoplasmosis in pregnant women or neonates between 1996 and 2000 in ten European centers. At 3 years of age, parents of children with and without congenital toxoplasmosis were surveyed about their child's development, behavior, and impairment, and about parental concerns and anxiety, using a postal questionnaire.

Results

Parents of 178/223 (80%) infected, and 527/821 (64%) uninfected children responded. We found no evidence that impaired development or behavior were more common in infected children, or that any potential effect of congenital toxoplasmosis was masked by prenatal treatment. Parents of infected children were significantly more anxious and reported more visual problems in their children.

Conclusion

On average, children aged three to four years with congenital toxoplasmosis identified by screening and treated during infancy in this European setting had risks of abnormal development and behavior similar to uninfected children. Parental anxiety about infected children needs to be addressed by clinicians. Future studies with longer follow up and clinician-administered assessments may be better able to detect any subtle differences in child outcomes.

Ocular manifestations in congenital toxoplasmosis

BACKGROUND

Retinochoroiditis is the most common ocular manifestation of congenital toxoplasmosis, but other associated ophthalmological pathologies can also occur. The aim of this study was to determine the nature of the latter in treated cases of the disease and to assess their impact on visual function.

METHODS

Four hundred and thirty consecutive children with serologically confirmed congenital toxoplasmosis were included in this study. Data were prospectively collected using standardized ophthalmological assessment forms. The presence of retinochoroiditis and of associated pathologies was ascertained, and their impact on visual function was assessed.

RESULTS

After a median follow-up of 12 years [range 0.6-26 years], 130 children manifested retinochoroiditis. We detected 22 foci of retinochoroiditis at birth and 264 additional ones during the follow-up period. Of these, 48 (17%) were active when first diagnosed. Twenty-five of the 130 children (19%) had other associated ocular pathologies. Of these, 21 (16%) had a strabismus, which was due to macular lesions in 86% of the cases; 7 (5.4%) presented with unilateral microphthalmia, and 4 (3%) with cataracts. Most of these events were detected after the onset of retinochoroiditis. None of the children presented with ocular involvement in the absence of chorioretinal lesions. Macular lesions occurred more frequently in children with associated pathologies (p<0.0001), and associated pathologies were likewise more common in individuals with macular lesions (p=0.0003). Visual impairment occurred in 31/130 cases, and in all but 3 of these eyes it was due not to an associated pathology but to macular retinochoroiditis.

CONCLUSIONS

At the end of the follow-up period, ocular involvement existed in 30% of the treated children with congenital toxoplasmosis. Associated eye pathologies were manifested less frequently than anticipated. They may occur later in life and are an indirect marker of the severity of congenital toxoplasmosis, but they do not have a direct impact on visual acuity. The overall functional prognosis of congenital toxoplasmosis is better than would be expected on the basis of literature findings, with only 2 of the 130 children suffering bilateral visual impairment.