Clinical value of specific immunoglobulin E detection by enzyme-linked immunosorbent assay in cases of acquired and congenital toxoplasmosis

Effective factors in the pathogenesis of Toxoplasmagondii

Toxoplasma gondii (T. gondii) is a cosmopolitan protozoan parasite in humans and animals. It infects about 30 % of the human population worldwide and causes potentially fatal diseases in immunocompromised hosts and neonates. For this study, five English-language databases (ScienceDirect, ProQuest, Web of Science, PubMed, and Scopus) and the internet search engine Google Scholar were searched. This review was accomplished to draw a global perspective of what is known about the pathogenesis of T. gondii and various factors affecting it. Virulence and immune responses can influence the mechanisms of parasite pathogenesis and these factors are in turn influenced by other factors. In addition to the host's genetic background, the type of Toxoplasma strain, the routes of transmission of infection, the number of passages, and different phases of parasite life affect virulence. The identification of virulence factors of the parasite could provide promising insights into the pathogenesis of this parasite. The results of this study can be an incentive to conduct more intensive research to design and develop new anti-Toxoplasma agents (drugs and vaccines) to treat or prevent this infection. In addition, further studies are needed to better understand the key agents in the pathogenesis of T. gondii.

Anti-Toxoplasma gondii IgM Long Persistence: What Are the Underlying Mechanisms?

Diagnosis of Toxoplasma gondii acute infection was first attempted by detection of specific IgM antibodies, as for other infectious diseases. However, it was noted that this immunoglobulin declines slowly and may last for months or even years. Apart from the diagnostic problem imposed on clinical management, this phenomenon called our attention due to the underlying phenomena that may be causing it. We performed a systematic comparison of reports studying IgM antibody kinetics, and the data from the papers were used to construct comparative plots and other graph types. It became clear that this phenomenon is quite generalized, and it may also occur in animals. Moreover, this is not a technical issue, although some tests make more evident the prolonged IgM decay than others. We further investigated biological reasons for its occurrence, i.e., infection dynamics (micro-reactivation–encystment, reinfection and reactivation), parasite strain relevance, as well as host innate, natural B cell responses and Ig class-switch problems inflicted by the parasite. The outcomes of these inquiries are presented and discussed herein.

Toxic 'Toxo' in the heart: Cardiac toxoplasmosis following a hematopoietic stem cell transplant- a case report

Toxoplasmosis is a rare but potentially severe complication after allogeneic hematopoietic cell transplantation. Toxoplasma gondii-associated cardiac involvement can cause myocarditis, pericarditis, arrhythmias, and congestive heart failure. Most cases with cardiac toxoplasmosis following BMT have been fatal and diagnosed at autopsy. We present an unfortunate case of sudden onset congestive heart failure symptoms and delayed post-transplant Toxoplasma PCR testing that ultimately led to the diagnosis of cardiac toxoplasmosis on autopsy in our patient.

Current perspective and scope of fetal therapy: part 2

Fetal therapy has been defined as any therapeutic intervention either invasive or noninvasive for correcting or treating any fetal malformation or condition. Invasive fetal therapy have its own set of maternal and fetal complications and invasive approach is not feasible in many of fetal conditions that are candidate for fetal therapy. Many such fetal conditions have been treated successfully by medical or noninvasive management. In medical fetal therapy, mothers are treated with medications which are transferred to fetus through placenta and exert positive effect on the fetus, thus avoiding complications that are seen secondary to invasive fetal therapy. The fetal conditions that have been managed with medical therapy includes fetal and neonatal alloimmune thrombocytopenia, neural tube defect, congenital adrenal hyperplasia, perinatal infections, respiratory distress syndrome, inborn error of metabolism, and congenital cystic adenomatoid malformation. This review will cover the medical or noninvasive aspect of fetal therapy and will highlight the progress made in the management of these fetal conditions.

The global seroprevalence of anti-Toxoplasma gondii antibodies in women who had spontaneous abortion: A systematic review and meta-analysis

BACKGROUND

Toxoplasma gondii (T. gondii) is an intracellular pathogen that can lead to abortion in pregnant women infected with this parasite. Therefore, the present study aimed to estimate the global seroprevalence of anti-T. gondii antibodies in women who had spontaneous abortion based on the results of published articles and evaluate the relationship between seroprevalence of anti-T. gondii antibodies and abortion via a systematical review and meta-analysis.

METHODS

Different databases were searched in order to gain access to all studies on the seroprevalence of anti- T. gondii antibodies in women who had spontaneous abortion and association between seroprevalence of anti-T. gondii antibodies and abortion published up to April 25th, 2019. Odds ratio (OR) and the pooled rate seroprevalence of T. gondii with a 95% confidence interval (CI) were calculated using the random effects model.

RESULTS

In total, 8 cross-sectional studies conducted on 1275 women who had abortion in present pregnancy, 40 cross-sectional studies performed on 9122 women who had a history of abortion, and 60 articles (involving 35 cross-sectional studies including 4436 women who had spontaneous abortion as case and 10398 as control and 25 case-control studies entailing 4656 cases and 3178 controls) were included for the final analyses. The random-effects estimates of the prevalence of anti-T. gondii IgG antibody in women who had abortion in present pregnancy and women who had a history of abortion were 33% (95% CI: 17%-49%) and 43% (95% CI: 27%-60%), respectively. In addition, the pooled OR for anti-T. gondii IgG antibody in cross-sectional and case-control studies among women who had spontaneous abortion were 1.65 (95% CI: 1.31-2.09) and 2.26 (95% CI: 1.56-3.28), respectively. Also, statistical analysis showed that the pooled OR of the risk of anti-T. gondii IgM antibody 1.39 (95% CI: 0.61-3.15) in cross-sectional and 4.33 (95% CI: 2.42-7.76) in case-control studies.

CONCLUSION

Based on the results of the current study, T. gondii infection could be considered a potential risk factor for abortion. It is recommended to carry out further and more comprehensive investigations to determine the effect of T. gondii infection on abortion to prevent and control toxoplasmosis among pregnant women around the world.

Antigens to detect the acute phase of toxoplasmosis in pregnant women: standardized comparison

A key element in any diagnostic technique is the antigen (Ag), a biomarker, but this is usually a protein that has a function to the parasite. Some biological aspects of the Ags and of the Toxoplasma gondii can influence the effectiveness of the diagnosis, as well as the antibody isotype and the characteristics of the assay. A large number of papers have assessed different proteins to distinguish the phases of infection, but the ‘indices of effectiveness’ differ among reports. This work presents for the first time a summary of all the Ags that have been evaluated, with standardized measurements of sensitivity and specificity. These values were calculated with information presented in the papers on Ag evaluations to differentiate the infection phases.

Relevance of and New Developments in Serology for Toxoplasmosis

Toxoplasmosis is a widespread parasitic disease caused by the intracellular parasite Toxoplasma gondii with a wide spectrum of clinical outcomes. The biological diagnosis of toxoplasmosis is often difficult and of paramount importance because clinical features are not sufficient to discriminate between toxoplasmosis and other illnesses. Serological tests are the most widely used biological tools for the diagnosis of toxoplasmosis worldwide. This review focuses on the crucial role of serology in providing answers to the most important questions related to the epidemiology and diagnosis of toxoplasmosis in human pathology. Notwithstanding their undeniable importance, serological tools need to be continuously improved and the interpretation of the ensuing results remains complex in many circumstances.

Laboratory Diagnosis of Congenital Toxoplasmosis

Recent studies have demonstrated that screening and treatment for toxoplasmosis during gestation result in a decrease of vertical transmission and clinical sequelae. Early treatment was associated with improved outcomes. Thus, laboratory methods should aim for early identification of infants with congenital toxoplasmosis (CT). Diagnostic approaches should include, at least, detection of Toxoplasma IgG, IgM, and IgA and a comprehensive review of maternal history, including the gestational age at which the mother was infected and treatment. Here, we review laboratory methods for the diagnosis of CT, with emphasis on serological tools. A diagnostic algorithm that takes into account maternal history is presented.

Evaluation of the liaison automated testing system for diagnosis of congenital toxoplasmosis

Congenital toxoplasmosis is a worldwide health problem, and different screening strategies exist. Testing of toxoplasma-specific antibodies in infants identifies congenital toxoplasmosis during the first year of life. However, experience with commercial available immunoassays is limited. The aim of this study was to evaluate both the performance and analytical characteristics of the Liaison diagnostic system in infants. In a retrospective study, serum Toxoplasma gondii antibodies were measured in samples from 333 infants, including 212 noninfected infants and 121 infants with congenital toxoplasmosis. A total of 1,157 umbilical cord blood and peripheral serum samples were analyzed. Liaison toxoplasma-specific IgG and IgM antibodies and the IgG avidity index were compared to the infection status of the infant, determined by the Sabin-Feldman dye test and immunosorbent agglutination assay--IgM. All noninfected infants were seronegative by Liaison IgG within the first year of life. The Liaison system showed a sensitivity of 81.8%, a specificity of 100.0%, a positive predictive value of 100.0%, a negative predictive value of 90.6%, and overall agreement of 84.4% by comparison with the dye test. Overall agreement of both IgM test systems was 96.0%. In this study cohort, avidity did not show a potential diagnostic benefit for the detection of congenital infection. In conclusion, the Liaison system is a valuable tool to monitor the serologic course of infants at risk. A final serologic confirmatory test is recommended to improve the rate of detection of congenital toxoplasmosis at 1 year of life. Protocols of routine follow-up testing in infants and accurate diagnostic tools after acute gestational infections are needed to improve medical care.

Epidemiology of and diagnostic strategies for toxoplasmosis

The apicomplexan parasite Toxoplasma gondii was discovered a little over 100 years ago, but knowledge of its biological life cycle and its medical importance has grown in the last 40 years. This obligate intracellular parasite was identified early as a pathogen responsible for congenital infection, but its clinical expression and the importance of reactivations of infections in immunocompromised patients were recognized later, in the era of organ transplantation and HIV infection. Recent knowledge of host cell-parasite interactions and of parasite virulence has brought new insights into the comprehension of the pathophysiology of infection. In this review, we focus on epidemiological and diagnostic aspects, putting them in perspective with current knowledge of parasite genotypes. In particular, we provide critical information on diagnostic methods according to the patient's background and discuss the implementation of screening tools for congenital toxoplasmosis according to health policies.

Severe congenital toxoplasmosis in the United States: clinical and serologic findings in untreated infants

BACKGROUND

Congenital toxoplasmosis can cause significant neurologic manifestations and other untoward sequelae.

METHODS

The Palo Alto Medical Foundation Toxoplasma Serology Laboratory database was searched for data on infants 0 to 180 days old, in whom congenital toxoplasmosis had been confirmed and who had been tested for Toxoplasma gondii-specific immunoglobulin G (IgG), IgM, and IgA antibodies, between 1991 and 2005. Their clinical findings were confirmed at the National Collaborative Chicago-based Congenital Toxoplasmosis Study center. We reviewed available clinical data and laboratory profiles of 164 infants with congenital toxoplasmosis whose mothers had not been treated for the parasite during gestation.

RESULTS

One or more severe clinical manifestations of congenital toxoplasmosis were reported in 84% of the infants and included eye disease (92.2%), brain calcifications (79.6%), and hydrocephalus (67.7%). In 61.6% of the infants, eye disease, brain calcifications, and hydrocephalus were present concurrently. T. gondii-specific IgM, IgA, and IgE antibodies were demonstrable in 86.6%, 77.4%, and 40.2% of the infants, respectively. Testing for IgM and IgA antibodies increased the sensitivity of making the diagnosis of congenital toxoplasmosis to 93% compared with testing for IgM or IgA individually. IgM and IgA antibodies were still present in 43.9% of infants diagnosed between 1 and 6 months of life.

CONCLUSIONS

Our study reveals that severe clinical signs of congenital toxoplasmosis including hydrocephalus, eye disease, or intracranial calcifications occurred in 85% infants whose sera were referred to our reference Toxoplasma Serology Laboratory during a period of 15 years. Laboratory tests, including serologic and polymerase chain reaction tests, were critical for diagnosis in the infants. Our results contrast remarkably with those of European investigators who rarely observe severe clinical signs in infants with congenital toxoplasmosis.

Congenital toxoplasmosis: evaluation of molecular and serological methods for achieving economic and early diagnosis among Egyptian preterm infants

BACKGROUND

Early diagnosis of congenital toxoplasmosis (CT) is difficult when specific immunoglobulin M (IgM) antibodies are absent, or if persist for months, in the newborn infant's blood.

OBJECTIVES

To study the risk factors of neonatal toxoplasmosis and to compare different immunologic profiles (Toxoplasma-specific IgM, IgA antibodies and the avidity of IgG antibodies) with polymerase chain reaction (PCR) for reaching economic and early postnatal diagnosis.

MATERIALS AND METHODS

We prospectively studied 80 preterm neonates, recruited from neonatal intensive care units (NICUs) of Cairo University hospitals. Whose gestational age ≤ 34 weeks with (n = 60) or without (n = 20) CT risk. Serum samples for specific IgA, IgM antibodies and avidity of IgG toxoplasma antibodies were measured by ELISA then compared to PCR.

RESULTS

Of the 60 studied cases, 16 (26.7%) were positive for toxoplasmosis by PCR, of which 15 (25%) had low avidity of IgG antibodies (positive), 14 (23.3%) were positive for IgA and 10 (16.7%) were positive for IgM, with sensitivity for avidity of IgG, IgA and IgM: 93.2%, 87.5% and 62.5%, respectively.

CONCLUSION

Determination of avidity of IgG toxoplasma antibodies and/or serological detection of specific IgA for toxoplasmosis offer, simple tests for diagnosis of congenital toxoplasmosis with (better sensitivity) than IgM.

Toxoplasma gondii infection in pregnancy: opportunities and pitfalls of serological diagnosis

Because of its life cycle, the recovery of Toxoplasma gondii from biological samples is often impracticable. Consequently, a serological diagnosis represents the first and the most widely used approach to defining the stage of infection. The detection of IgG, IgM, IgA, IgE and IgG avidity by different methods offers this opportunity. However, the results may be affected by difficulties in interpretation, as the same antibody pattern may have a different valency, contingent upon subjects and clinical settings, e.g., pregnant women vs. neonates, and treated vs. untreated patients. This review describes the various factors that should be taken into account when performing serological tests for T. gondii, as well as the pitfalls that may be encountered during the interpretative process.

Evaluation of a commercial IgE ELISA in comparison with IgA and IgM ELISAs, IgG avidity assay and complement fixation for the diagnosis of acute toxoplasmosis

A panel of sera from patients with known case histories representative of acute toxoplasmosis (primarily lymphadenopathy, n = 106), latent toxoplasmosis (asymptomatic, n = 368) and negative samples (n = 54) was used to evaluate the capacity of five serological tests to differentiate among patients with acute or latent toxoplasmosis and non-infected individuals. Positive IgA, IgE and IgM ELISA results and low IgG avidity and complement fixation test (CFT) titres of >or=256 were considered to be indicative of acute toxoplasmosis. The most sensitive methods were IgM ELISA (98.1%) and CFT (97.1%), albeit with low specificity (65.0% and 64.5%, respectively) and positive predictive values (43.3% and 42.7%, respectively). IgG avidity assay and IgE ELISA had the highest specificity (97.7% and 91.7%, respectively) and the highest positive predictive values (89.4% and 75.6%, respectively). The best association between serological results and clinical findings was obtained with IgE ELISA (86%, as expressed via Youden's index). In a subset of 259 samples categorised by the period between the onset of clinical symptoms and sampling, >50% of patients had enlarged lymph nodes for <4 months, despite a broad range of differences. However, IgM remained positive for 12-18 months, IgA for 6-9 months and IgE for 4-6 months. IgG avidity remained low for a maximum of 4 months, after which avidity increased despite the persistence of enlarged lymph nodes and a positive IgE assay. Detection of IgE appears to be a highly specific test for confirming the acute nature of Toxoplasma infections that have been detected by other sensitive methods.