PCR em tempo real no diagnóstico da toxoplasmose congênita / Real-time PCR in the diagnosis of congenital toxoplasmosis

O diagnóstico da toxoplasmose congênita apresenta limitações sendo, portanto, necessárias novas opções de exames. A análise do líquido aminiótico pela PCR em tempo real já se mostrou eficaz para confirmação da infecção fetal. No entanto, o seu desempenho em outras amostras biológicas ainda não está claro. O objetivo deste estudo é avaliar a PCR em tempo real no sangue da mãe e do recém-nascido assim como no líquido amniótico e placenta, no diagnóstico da toxoplasmose congênita. Esse é um estudo descritivo de gestantes com toxoplasmose acompanhadas no Rio de Janeiro, Brasil. Foi realizada PCR em tempo real em amostras de sangue materno, líquido amniótico, placenta e sangue dos recém-nascidos e o exame histopatológico das placentas. Também foram coletados dados clínicos e laboratoriais dos recém-nascidos. Foram acompanhadas 116 gestantes e analisadas 298 amostras. Uma (0,9%) gestante apresentou PCR positiva no sangue, três (3,5%) no líquido amniótico, uma (2,3%) na placenta e nenhum recém-nascido apresentou PCR positiva no sangue. O estudo histopatológico foi sugestivo de infecção por toxoplasmose em 24 (49%) placentas. Seis (5,2%) recém-nascidos foram diagnosticados com toxoplasmose congênita e apenas os casos com PCR positiva no líquido amniótico tinham associação do resultado da PCR com o diagnóstico de infecção congênita. Tanto as amostras de sangue materno quanto as de sangue dos recém-nascidos e placenta, não demonstraram ser promissoras no diagnóstico da toxoplasmose congênita. Novos estudos são necessários para avaliar o real papel do diagnóstico molecular em outros materiais biológicos que não o líquido amniótico.

The diagnosis of congenital toxoplasmosis has limitations so new options are needed. Real-time PCR analysis of amniotic fluid has proven effective for confirming fetal infection. However, its performance in other biological samples still needs to be determined. This study aims to evaluate the real-time PCR role in the blood of the mother and newborn as well as in the amniotic fluid and placenta, in congenital toxoplasmosis diagnosis. It is a descriptive study of pregnant women with toxoplasmosis followed in Rio de Janeiro, Brazil. Real-time PCR was performed on maternal blood, amniotic fluid, placenta, and newborn blood samples. In addition, a histopathological examination of the placentas was performed and data from the babies were collected. One hundred and sixteen pregnant women were followed and 298 samples were analyzed. One (0.9%) pregnant woman had positive PCR in the blood, three (3.5%) in the amniotic fluid, one (2.3%) in the placenta, and any newborn had positive PCR in the blood. The histopathological study suggested toxoplasmosis infection in 24 (49%) placentas. Six (5.2%) newborns were diagnosed with congenital toxoplasmosis and only the cases with positive PCR in amniotic fluid associated with the diagnosis of congenital infection. Neither maternal nor newborn blood and placenta samples have not shown promise in diagnosing congenital toxoplasmosis. Further studies are needed to evaluate the fundamental role of molecular diagnostics in others biological materials than amniotic fluid.

Effector Vγ9Vδ2 T cell response to congenital Toxoplasma gondii infection.

A major γδ T cell population in human adult blood are the Vγ9Vδ2 T cells that are activated and expanded in a TCR-dependent manner by microbe-derived and endogenously derived phosphorylated prenyl metabolites (phosphoantigens). Vγ9Vδ2 T cells are also abundant in human fetal peripheral blood, but compared with their adult counterparts they have a distinct developmental origin, are hyporesponsive toward in vitro phosphoantigen exposure, and do not possess a cytotoxic effector phenotype. In order to obtain insight into the role of Vγ9Vδ2 T cells in the human fetus, we investigated their response to in utero infection with the phosphoantigen-producing parasite Toxoplasma gondii (T. gondii). Vγ9Vδ2 T cells expanded strongly when faced with congenital T. gondii infection, which was associated with differentiation toward potent cytotoxic effector cells. The Vγ9Vδ2 T cell expansion in utero resulted in a fetal footprint with public germline-encoded clonotypes in the Vγ9Vδ2 TCR repertoire 2 months after birth. Overall, our data indicate that the human fetus, from early gestation onward, possesses public Vγ9Vδ2 T cells that acquire effector functions following parasite infections.

High performance of a novel point-of-care blood test for Toxoplasma infection in women from diverse regions of Morocco.

Point-of-care (POC) testing for Toxoplasma infection has the potential to revolutionize diagnosis and management of toxoplasmosis, especially in high-risk populations in areas with significant environmental contamination and poor health infrastructure precluding appropriate follow-up and preventing access to medical care. Toxoplasmosis is a significant public health challenge in Morocco, with a relatively heavy burden of infection and, to this point, minimal investment nationally to address this infection. Herein, we analyse the performance of a novel, low-cost rapid test using fingerstick-derived whole blood from 632 women (82 of whom were pregnant) from slums, educational centres, and from nomad groups across different geographical regions (i.e. oceanic, mountainous) of Morocco. The POC test was highly sensitive and specific from all settings. In the first group of 283 women, sera were tested by Platelia ELISA IgG and IgM along with fingerstick whole blood test. Then a matrix study with 349 women was performed in which fingerstick - POC test results and serum obtained by venipuncture contemporaneously were compared. These results show high POC test performance (Sensitivity: 96.4% [IC95 90.6-98.9%]; Specificity: 99.6% [IC95 97.3-99.9%]) and high prevalence of Toxoplasma infection among women living in rural and mountainous areas, and in urban areas with lower educational levels. The high performance of POC test confirms that it can reduce the need for venipuncture and clinical infrastructure in a low-resource setting. It can be used to efficiently perform seroprevalence determinations in large group settings across a range of demographics, and potentially expands healthcare access, thereby preventing human suffering.

The imbalance of TNF and IL-6 levels and FOXP3 expression at the maternal-fetal interface is involved in adverse pregnancy outcomes in a susceptible murine model of congenital toxoplasmosis.

Vertical transmission of Toxoplasma gondii leads to adverse pregnancy outcomes depending on the time at which the infection occurs and the immunological state of the mother. C57BL/6 and BALB/c mice have been described as susceptible and resistant mouse lineages to congenital T. gondii infection, respectively. This study aimed to elucidate the systemic and local cytokine profile of pregnant mice infected with T. gondii and whether the expression of the transcription factor FOXP3, related to T regulatory cells, is associated with the resistance/susceptibility of these lineages of mice in the context of experimental congenital toxoplasmosis. For this purpose, C57BL/6 and BALB/c females were orally infected with the T. gondii ME-49 strain on the day of vaginal plug detection or day 14 of gestation, examined 7 or 5 days later, respectively, as models of early and late pregnancy. Cytokine levels were measured systemically and in the uterus/placenta. Additionally, the uterus/placenta were evaluated macroscopically for resorption rates and histologically for parasite and FOXP3 immunostaining. The FOXP3 protein expression was also evaluated by western blotting assay. It was found that, during early pregnancy, the infection leads to high IFN-γ, TNF and IL-6 levels systemically, with the TNF levels being higher in C57BL/6 mice. At the maternal-fetal interface, the infection induced high levels of IFN-γ in both mouse lineages; however, higher levels were observed in BALB/c, while high TNF and IL-6 levels were found in C57BL/6, but not in BALB/c mice. In contrast, in late gestation, T. gondii interfered less strongly with the cytokine profile. In early pregnancy, a reduction of FOXP3 expression at the maternal-fetal interface of infected mice was also observed, and the reduction was larger in C57BL/6 compared with BALB/c mice. Additionally, the parasite was seldom found in the uterus/placenta. Thus, the worse pregnancy outcomes observed in C57BL/6 mice were associated with higher TNF systemically, and TNF and IL-6 at the maternal-fetal interface, with lower FOXP3 expression.

Validation of dried blood spots in monitoring toxoplasmosis.

Due to the growing importance of toxoplasmosis worldwide, simple methods of diagnosis are important for epidemiologic studies. Dried blood spot (DBS) is a useful tool that surpasses venipuncture. DBS-Toxoplasma testing via a finger-stick could also be used in setting where phlebotomies might not be feasible, such as worldwide prenatal and newborn screening for congenital toxoplasmosis. This study included 101 study subjects were occupationally at-risk to Toxoplasma gondii infection and 33 as controls. Serum was collected from both groups for the detection of anti-Toxoplasma IgG antibodies by ELISA as a reference gold standard test. For the occupational at-risk group, capillary finger stick derived blood was blotted onto five sets of Whatman protein saver cards. Discs were stored as four sets; three sets at 4°C and eluted 1, 2 and 3 months of storage and one set at -20°C for 3 months then eluted. Additionally, one set was eluted immediately. Anti-Toxoplasma IgG antibodies were evaluated by ELISA from DBS eluted samples and compared to matched sera. DBS elutes from discs that were freshly prepared for anti-Toxoplasma IgG showed 100% sensitivity, specificity and diagnostic accuracy. Serologic testing using DBS showed very good diagnostic accuracy under all mentioned conditions of storage. Higher stability was obtained when the blood discs stored at 4°C for 1 month and up to 3 months at -20°C, with 98.18% sensitivity, 100% specificity and 99% diagnostic accuracy. DBS-Toxoplasma testing is characterized by simplicity in performance, cost-effectiveness and the ease of handling, to store and to transport, with high diagnostic accuracy.

Performance of a Toxo IgM prototype assay for the diagnosis of maternal and congenital Toxoplasma infections.

Background Testing for anti-Toxoplasma immunoglobulin (Ig)M is of main importance in the context of pregnancy to promptly alert to an acute maternal infection prior to the detection of IgG and to identify infected newborns. Their absence helps exclude a recent maternal infection in the presence of IgG. Methods The performance of a Toxo IgM immunocapture prototype assay (bioMérieux, France) was compared with that of the VIDAS® Toxo IgM and the ARCHITECT® Toxo IgM (Abbott, Germany) assays at Grenoble and Lyon (France). A total of 1446 sera were sampled from (i) 1054 pregnant women found by routine workup to have no infection (n = 843), an acute infection (<4 months) (n = 28) or a chronic infection (>4 months) with residual (n = 120) or no IgM (n = 62); (ii) 50 three-serum panels sampled immediately after a maternal seroconversion; (iii) 242 samples taken in 41 children with a congenital toxoplasmosis (n = 122) and in 40 uninfected children (n = 120). Results In pregnant women, the overall agreement with the VIDAS® assay was 99.23% (CI: 99.16-99.27) and that with the ARCHITECT® assay was 99.14% (CI: 99.07-99.17). Sensitivity of the Toxo IgM prototype assay was 100% (CI: 87.66-100.00) and specificity was 99.64% (98.96-99.93). In acute maternal infections, IgM assays were detected as early with the prototype as with the other two. In the congenitally infected children, IgM were detected on their first sample in 25/40 with the prototype vs. 23/40 with the VIDAS® test. No uninfected child had positive IgM. Conclusion The prototype performed comparably to the ARCHITECT® and VIDAS® Toxo IgM assays for the diagnosis of maternal and congenital toxoplasmosis.

Basic heel prick test: inclusion of screening, diagnosis and criteria for early confirmation of congenital infection by Toxoplasma gondii.

Toxoplasma gondii can cross the placental barrier, causing fetal infection with potentially severe sequelae. The aim of this study was to evaluate whether the serological screening for toxoplasmosis should be included in the basic neonatal heel prick test in order to establish criteria for the confirmation and/or exclusion of the diagnosis of congenital infection in newborns treated at three public health units in the metropolitan region of Goiania, Goias State, Brazil. Blood samples were collected on filter paper from newborns and later, peripheral blood samples from the mothers and their respective children were obtained to confirm or exclude the diagnosis of suspected congenital infection, by means of an enzyme-linked immunosorbent assay (IgM and IgG) and a polymerase chain reaction assay. From a total of 1,159 blood samples collected on filter paper, 43.92% were reactive to IgG and 0.17% to anti-T. gondii IgM and IgG. One hundred and twenty-seven paired samples (mother and child) were collected following consensual protocols for peripheral blood collection. Results obtained from the filter paper and peripheral blood of the newborns were 90.55% concordant. A comparison of the mother and child blood test results showed agreement regarding the detection of IgG in 90.48% of the samples. The parasite DNA was detected in the peripheral blood of one child. In view of the results obtained in this study, the inclusion of the serological screening for toxoplasmosis in the newborn heel prick test proved to be effective for the early detection of congenital T. gondii infection.

A cohort study of maternal screening for congenital Toxoplasma gondii infection: 12 years' experience.

Primary infection with Toxoplasma gondii (T. gondii) during pregnancy may cause congenital infection of the infant. This study evaluated whether screening using IgG avidity and multiplex-nested polymerase chain reaction (PCR) methods was effective for detecting a high-risk pregnancy for congenital T. gondii infection. In a prospective cohort study serum T. gondii IgG avidity was measured in 469 pregnant women who had a positive test for T. gondii antibody plus a positive or equivocal test for IgM. Multiplex-nested PCR for T. gondii DNA on amniotic fluid, maternal blood, and neonatal blood was performed with informed consent. Low (<30%), borderline (30-35%), and high (>35%) IgG avidity indices were found in 104 (22.2%), 30 (6.4%), and 305 (71.4%), respectively. A total of 12 cases had a positive PCR test for amniotic fluids of the prenatal amniocentesis or at birth, or neonatal blood. Seven of the 12 cases were diagnosed as having congenital T. gondii infection, and they had low IgG avidity indices. Congenital T. gondii infection screening using of IgG avidity and multiplex-nested PCR methods for pregnant women with a positive test for T. gondii antibody plus a positive or equivocal test for T. gondii IgM was useful for detecting a high-risk pregnancy and diagnosing congenital T. gondii infection.

Congenital toxoplasmosis in the United States: clinical and serologic findings in infants born to mothers treated during pregnancy.

We assessed clinical and serologic findings in 25 infants with congenital toxoplasmosis born to mothers treated during pregnancy in the United States. Results indicate a lower prevalence of eye findings and hydrocephalus in the group of infants born to treated mothers (62.5% and 38.5%, respectively) compared to results on the same pathologies reported in our previous cohort of infants born to untreated mothers (92.2% and 67.7%, respectively). The sensitivity of the IgM ISAGA and IgA ELISA in the present study were lower (44% and 60%, respectively) compared to sensitivity of these methods in our previously studied group of infants born to untreated mothers (86.6% and 76.5%, respectively). These findings provide further evidence that anti-parasitic treatment if administered during pregnancy can contribute to better clinical outcomes, even in countries where systematic screening and treatment have not been routinely implemented.

Congenital human toxoplasmosis caused by non-clonal Toxoplasma gondii genotypes in Argentina.

Toxoplasmosis, a worldwide distributed zoonosis, can be transmitted congenitally affecting fetuses and developing variable clinical signs. Different Toxoplasma gondii genotypes and infective dose are related factors with different clinical manifestations. Several studies indicate that atypical strains could produce more severe clinical manifestations compared to typical strains. Umbilical cord blood (n = 37) and placenta (n = 19) were collected at birth from women with acute T. gondii infection and processed for isolation by mice bioassay. Six isolates were obtained and identified as TgHm14-4Arg, TgHm15-02Arg, TgHm16-01Arg, TgHm16-02Arg, TgHm17-01Arg and TgHm17-02Arg. Three genotypes described previously on Toxo-DB were identified: #138 identified in chickens from Brazil, #182 isolated from eared doves from Brazil, #14 from wallaby kangaroos and chickens from Argentina, chickens from Brazil, Colombia, Chile and Venezuela, cats and dogs from Brazil and Colombia and also coyotes from USA indicating worldwide distribution of these genotypes. Two new allele combinations were obtained showing high genotypes diversity in Argentina. Four of the isolates (TgHm14-4Arg, TgHm15-02Arg, TgHm16-01Arg, TgHm16-02Arg) and two of them (TgHm17-01Arg, TgHm17-02Arg) produced chronic and acute infections in mice, respectively. Until now, seven T. gondii isolates have been obtained from humans in Argentina, and all were atypical or non-clonal genotypes. The identification of atypical strains causing congenital toxoplasmosis and circulating in our region, make important to perform the serological screenings according Argentine Consensus of Toxoplasmosis and to apply and monitoring treatments earlier in pregnancy. To achieve this aim, it is necessary to inform general population about T. gondii infection, diagnostics and control measures. These results should serve to generate awareness about congenital toxoplasmosis in South America.

Epidemiological profile of 39 cases of microcephaly caused by congenital infections diagnosed in the state of Rio Grande do Sul between 2015-2017

Introduction: Microcephaly is a clinical finding that can arise from congenital anomalies or emerge after childbirth. Maternal infections acquired during pregnancy can result in characteristic brain damage in the newborn (NB), which may be visible even in the fetal stage. To describe the epidemiological profile of newborns with reported microcephaly and diagnosed with congenital infections in the state of Rio Grande do Sul between 2015 and 2017. Methods: A cross-sectional study was carried out on data collected from the Public Health Event Registry as well as from medical records. The investigation included serologies for toxoplasmosis and rubella; polymerase chain reaction (PCR) for Zika virus (ZIKV) in the blood and cytomegalovirus in the urine; non-treponemal tests for syphilis; and brain imaging tests. Results: Of the 257 reported cases of microcephaly, 39 were diagnosed with congenital infections. Severe microcephaly was identified in 13 patients (33.3%) and 51.3% of the cases showed alterations in brain imaging tests. In relation to the diagnosis of congenital infections, three patients (7.7%) were diagnosed with ZIKV, nine (23.1%) with cytomegalovirus, nine (23.1%) with toxoplasmosis, and 18 (46.1%) with congenital syphilis. The three cases of ZIKV showed calcification in brain imaging tests, signs of arthrogryposis, excess occipital skin and irritability, characterizing the typical phenotype of ZIKV infection. Conclusions: Most cases of congenital infection had severe neurological lesions, particularly the cases of ZIKV, which can cause neurodevelopmental delays and sequelae in these infants throughout early childhood.

Preventing congenital toxoplasmosis - implementation of clinical practice guidelines.

OBJECTIVES: The aim of the study was to evaluate obstetric care of pregnant women with regard to prevention of congenital toxoplasmosis. Additionally, we attempted to determine the frequency of markers for past infection with Toxoplasma gondii in order to characterize the current significance of preventive measures in the Polish population. MATERIAL AND METHODS: The analysis of the medical records - pregnancy charts of women who presented for delivery - was performed. Patient age, place of residence, and toxoplasmosis test (or lack of it) were evaluated. Also, further diagnostic management, depending on the serologic result, was investigated. RESULTS: Out of 670 pregnant women, 628 (93.73%) underwent at least one toxoplasmosis diagnostic test. Out of those, 502 (73%) had a negative result (IgG -, IgM -), and 2 (0.32%) had a positive result (IgG +, IgM +), while history of infection with Toxoplasma gondii was confirmed (IgG +, IgM -) in 124 (19.75%) cases. Repeat testing was required in 183 (29.14%) out of the 628 women. CONCLUSIONS: A high rate of women in whom IgG antibodies were not detected in the first test and a low rate of women who required repeat testing later in pregnancy are noteworthy. Regardless of the healthcare policy, parents should receive reliable information about the nature of the disease and possibilities of prevention, while medical professionals ought to have easy access to research data about the epidemiologic status and recommendations.

Use of polymerase chain reaction (PCR) in the diagnosis of congenital toxoplasmosis.

Congenital toxoplasmosis (CT) is a parasitic disease that causes serious fetal and neonatal harm or death. In countries that do not have antenatal screening programs, the initiation of CT treatment relies on a postnatal diagnosis. Until recently, diagnosis was based on clinical signs and immunoglobulin seropositivity, which is fraught with difficulty. In these cases, diagnosis was often delayed or treatment, which carries risk, started empirically. We highlight the use of polymerase chain reaction to diagnose a case of congenital toxoplasmosis, allowing early treatment and justifying the treatment burden.

[Management of Toxoplasmic Seroconversion in the Third Trimester of Pregnancy in Tunisia]. / Particularités de la prise en charge en Tunisie des séroconversions toxoplasmiques du troisième trimestre de grossesse.

The purpose of our study was to report the particularities of the management of toxoplasmosis seroconversion cases occurred during the third trimester of pregnancy and diagnosed in the Institute Pasteur of Tunis. The study was conducted in the Laboratory of Parasitology-Mycology of the Institute Pasteur of Tunis between January 2005 and December 2017. A total of 27 cases of toxoplasmosis seroconversion during the third trimester were included. Prenatal diagnosis was performed in five cases. PCR was positive in one case. Pyrimethamine-sulfadoxine was prescribed in one case with positive PCR and in another case as soon as maternal infection was confirmed. Spiramycine was prescribed in 24 cases for the duration of the pregnancy. One woman did not take any treatment because seroconversion was diagnosed just before delivery. Twenty newborns had congenital toxoplasmosis: 19 cases were diagnosed by serology and one case was diagnosed after amniocentesis. Two newborns (10%) were symptomatic at birth. All the newborns had neither clinical nor radiological signs during the follow-up.

L'objectif de notre travail était de rapporter les particularités de la prise en charge d'une série de cas de séroconversion toxoplasmique du troisième trimestre de grossesse diagnostiquée à l'institut Pasteur de Tunis. Il s'agit d'une étude rétrospective colligée au laboratoire de parasitologie-mycologie de l'institut Pasteur de Tunis entre janvier 2005 et décembre 2017, incluant 27 femmes enceintes ayant présenté une séroconversion toxoplasmique au cours du troisième trimestre de la grossesse diagnostiquée au cours de leurs suivis sérologiques. Cinq femmes ont bénéficié d'un diagnostic anténatal. La PCR (polymerase chain reaction) s'est révélée positive dans un seul cas. Deux femmes ont été mises sous pyriméthamine-sulfadoxine dont une avait une PCR positive. La spiramycine a été instituée chez 24 femmes jusqu'à l'accouchement. Une femme n'a reçu aucun traitement, la séroconversion ayant été diagnostiquée la veille de l'accouchement. Le diagnostic de la toxoplasmose congénitale a été retenu chez 20 nouveau-nés (74 %) dont un en anténatal et 19 à la naissance. Deux étaient symptomatiques (10 %) à la naissance. Aucune manifestation clinique ou radiologique n'a été observée au cours de leurs suivis.

Establishing tools for early diagnosis of congenital toxoplasmosis: Flow cytometric IgG avidity assay as a confirmatory test for neonatal screening.

The aim of this study was to evaluate the performance of conventional serology (Q-Preven™ and ELFAVIDAS™) and flow cytometry-based serologic tools for early serologic diagnosis of congenital toxoplasmosis. The study groups included prospectively confirmed cases of congenital toxoplasmosis (TOXO=88) and age-matching non-infected controls (NI=15).The results demonstrated that all samples tested positive/indeterminate for anti-T. gondii IgM screening at birth using air-dried whole blood samples. Serum samples collected at 30-45days after birth tested positive for ELFAVIDAS™ IgG in both groups. While all NI tested negative for ELFAVIDAS™ IgM and IgA, only 78% and 36% of TOXO tested positive for IgM and IgA, respectively. Flow cytometry-based anti-T. gondii IgM, IgA and IgG reactivity displayed moderate performance with low sensitivity (47.6%, 72.6% and 75.0%, respectively). Regardless the remarkable specificity of IgG1, IgG2 and IgG3 subclasses for early diagnosis, weak or moderate specificity was observed (Se=73.9%, 60.2% and 83.0%, respectively). The analysis of IgG avidity indices (AI) demonstrated the highest performance among the flow cytometry-based methods (Se=96.6%; Sp=93.3%), underscoring the low avidity index (AI<60%) within TOXO (97.0%) in contrast with the high avidity index (AI>60%) in NI (93%). Analysis of anti-T. gondii IgG and IgG3 reactivity for mother:infant paired samples may represent a relevant complementary tests for early diagnosis. In conclusion, a feasible high-standard algorithm (Accuracy=97.1%) was proposed consisting of Q-Preven™ IgM screening at birth, followed by ELFAVIDAS™ IgM and flow cytometric IgG avidity analysis at 30-45days after birth as a high performance tool for early serological diagnosis of congenital toxoplasmosis.

Toxoplasmosis: Seroprevalence in pregnant women, and serological and molecular screening in neonatal umbilical cord blood.

Toxoplasmosis is a common zoonotic disease that can also be transmitted from the mother to the embryo, with the risk of congenital infection varying around the world. The aim of this study was to screen pregnant women and their neonates for toxoplasmosis by serologic and molecular methods and assess the impact of risk factors associated with toxoplasmosis on the rate of congenital infection. This study was conducted at a regional maternity hospital in Arak, the capital of the Markazi Province in Iran, during a period of six months. All selected pregnant women (n=261) and the corresponding cord blood samples were serologically screened for toxoplasmosis, with seropositive samples also undergoing molecular testing. Demographic data, as well as information related to the risk factors associated with the transmission of the disease, were collected from mothers and their neonates. The detection of anti-Toxoplasma antibodies and the extraction of DNA from blood samples were conducted using commercial kits. Results showed that the sera of 87 maternal blood samples (33.3%) and 40 cord blood samples (15.3%) were positive for anti-Toxoplasma antibodies (IgG and/or IgM). Molecular screening of the seropositive samples only identified one positive cord blood sample. In other words, the diagnosis of congenital toxoplasmosis was definitive in only one neonate. There was no significant association between the risk of parasite transmission and neonatal seropositivity (p >0.05). Therefore, the results showed that the prevalence of congenital toxoplasmosis in the studied area was consistent with the global rate and suggest that the implementation of newborn screening and follow-up testing could help reduce the disease risk.

The IgG avidity value for the prediction of Toxoplasma gondii infection in the amniotic fluid.

Primary Toxoplasma gondii (T. gondii) infection during pregnancy may lead to congenital toxoplasmosis. Maternal screening using T. gondii IgG avidity measurement and multiplex nested PCR was performed. The aim of this prospective cohort study was to determine a cut-off value of IgG avidity index (AI) for the prediction of the presence of T. gondii DNA in the amniotic fluid. One hundred thirty-nine women with positive or equivocal tests for IgM underwent both serum IgG avidity measurement and PCR analysis for the amniotic fluid. Nine had positive PCR results, and three of them were diagnosed as having congenital infection. A cut-off value of IgG AI was determined using receiver operating characteristic analysis. IgG AI (mean 13%) in women with positive PCR results was significantly lower than that (39%) in women with negative results. A cut-off value of <25% IgG AI yields the best results with 77.8% sensitivity and 81.5% specificity for the presence of T. gondii DNA in the amniotic fluid. None of women with IgG AI of ≥30% had a positive PCR result or congenital infection. This study firstly demonstrated that a cut-off value of 25-30% IgG AI might be useful for the prediction of the presence of T. gondii DNA in the amniotic fluid and congenital infection.

An enhancement of ROC curves made them clinically relevant for diagnostic-test comparison and optimal-threshold determination.

OBJECTIVES: The receiver operating characteristic curves (ROC curves) are often used to compare continuous diagnostic tests or determine the optimal threshold of a test; however, they do not consider the costs of misclassifications or the disease prevalence. The ROC graph was extended to allow for these aspects. STUDY DESIGN AND SETTING: Two new lines are added to the ROC graph: a sensitivity line and a specificity line. Their slopes depend on the disease prevalence and on the ratio of the net benefit of treating a diseased subject to the net cost of treating a nondiseased one. First, these lines help researchers determine the range of specificities within which test comparisons of partial areas under the curves is clinically relevant. Second, the ROC curve point the farthest from the specificity line is shown to be the optimal threshold in terms of expected utility. RESULTS: This method was applied: (1) to determine the optimal threshold of ratio specific immunoglobulin G (IgG)/total IgG for the diagnosis of congenital toxoplasmosis and (2) to select, among two markers, the most accurate for the diagnosis of left ventricular hypertrophy in hypertensive subjects. CONCLUSION: The two additional lines transform the statistically valid ROC graph into a clinically relevant tool for test selection and threshold determination.

Multidisciplinary approach to congenital Toxoplasma infection: an Italian nationwide survey.

Italy provides a free voluntary serological screening for toxoplasmosis in pregnancy supported by public health system, as there is an estimated congenital toxoplasmosis rate of 1-2/10,000. The aim of this study was to make an inventory of diagnostic and therapeutic protocols in use in Italy in the absence of a national guideline. A semistructured questionnaire was distributed to AMCLI (Italian Association of Clinical Microbiologists) members who were asked to involve other specialists to fill in the form. Data from 26 centers show: a) a general use of the IgG avidity test to solve diagnosis in IgG/IgM positive, pregnant women; b) a widespread attitude to spyramicin antenatal treatment in suspected, unconfirmed maternal infection; c) avoidance of invasive antenatal diagnosis only in suspected early or late (>24 weeks), even confirmed, maternal infection d) fetal diagnosis performed by PCR assays on amniotic fluid; e) variability of both indications and dosage of pyrimethamine-sulfadiazine (P-S) as fetal treatment; f) use of comparative mother and newborn IgG/IgM Immuneblot in most centers; g) no diagnostic tests performed on placenta and cord blood; h) spyramicin is no longer used in congenital infections; i) no P-S-based treatment for children at high risk of congenital infection (late maternal infection) in the absence of diagnosis. As there is the opportunity to test pregnant women for Toxoplasma gondii infection in Italy free of charge, standardized diagnostic and therapeutic national guidelines would focus on a more uniform approach.

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.