Laboratory Diagnosis of Congenital Toxoplasmosis

In defense of children's brain: reshuffling the laboratory toolbox for the diagnosis of congenital toxoplasmosis

For decades, an immunosorbent agglutination assay (ISAGA) has been considered the gold standard method for the detection of Toxoplasma gondii-specific IgM in infants for the diagnosis of congenital toxoplasmosis (CT). The Toxoplasma IgM ISAGA was consistently reported as having superior sensitivity. Unfortunately, the commercial kit for the detection of Toxoplasma IgM ISAGA will no longer be available in 2024 and alternatives will only be available at a handful of reference laboratories as in-house or laboratory-developed tests. In a recent study, S. Arkhis, C. Rouges, N. Dahane, H. Guegan, et al. (J Clin Microbiol 62:e01222-23, 2024, https://doi.org/10.1128/jcm.01222-23), reported that the performance of the PLATELIA Toxo IgM was comparable to that of the ISAGA method for the diagnosis of CT. A second study revealing similar results supports the PLATELIA Toxo IgM as the new gold standard for the detection of T. gondii-specific IgM in infants. Although the laboratory toolbox for CT diagnosis has been reshuffled successfully, it is by universally implementing all available serological and molecular tools at the earliest possible time during gestation that we can best defend children's brain from the potential harm caused by trans-placentally transmitted T. gondii.

Seroprevalence of Toxoplasma gondii and Associated Risk Factors among Pregnant Women in Algeria

Toxoplasma gondii is an obligate intracellular protozoan parasite affecting all warm-blooded vertebrates, including humans. Infections in humans can lead to severe clinical manifestations in pregnant women and immunocompromised patients. The aim of the present study was to assess seroprevalence of T. gondii infection and to identify the associated risk factors among pregnant women from southern Algeria. A cross-sectional study was conducted from March 2021 to May 2022 among 1,345 pregnant women. A structured questionnaire was used to obtain information on risk factors associated with infection. Participants were screened for anti T. gondii IgG and IgM antibodies using the enzyme-linked fluorescent assay. The overall IgG and IgM seroprevalence was 13.6% and 0.89%, respectively. A significant association was found between seroprevalence of anti T. gondii IgG and history of spontaneous abortion (P = 0.016). Moreover, an increasing trend of seroprevalence was detected in the autumnal season (P = 0.030), and eating raw or undercooked meat was found to be significantly associated with anti-T. gondii IgM seropositivity (P = 0.002). Multivariate analysis showed that women who had experienced spontaneous abortion, regularly ate undercooked meat, and used bottled water in summer were more likely to contract infection with T. gondii. The majority (86.4%) of the studied pregnant women were serologically negative for toxoplasmosis and hence were susceptible to primary acute infection during pregnancy and possible fetal anomalies. Therefore, health education and awareness of the disease and its transmission to women, especially during pregnancy, is imperative.

Carbon nanospheres dual spectral-overlapped fluorescence quenching lateral flow immunoassay for rapid diagnosis of toxoplasmosis in humans

Toxoplasmosis is a common zoonotic disease caused by a protozoan parasite Toxoplasma gondii (Tox), approximately infecting one-third of human populations worldwide. This study developed the carbon nanospheres (CNPs) based dual spectral-overlapped fluorescence quenching lateral flow immunoassay (CNPs-FQLFIA) for detection of Tox antibodies (ToxAbs). The CNPs have been effectively coupled with Tox antigen (ToxAg), which can completely overlap the excitation and emission spectra of europium nanospheres (EuNPs) and CdSe/ZnS quantum dots (QDs) in testing strips of CNPs-QDs-FQLFIA or CNPs-EuNPs-FQLFIA. The sensitivity of CNPs-EuNPs-FQLFIA or CNPs-QDs-FQLFIA was 4 or 8 IU/mL under natural light readout, or both 4 IU/mL ToxAbs under ultraviolet (UV) light readout by the naked eyes, respectively. The limit of detection (LOD) of two types of CNPs-FQLFIA was both 1 IU/mL ToxAbs under UV light by a dry fluorescence analyzer, but no cross-reaction was found with other antibodies. The intra-assay coefficient variation (CV) of both CNPs-EuNPs-FQLFIA and CNPs-QDs-FQLFIA was less than 8%, while the inter-assay CV was less than 14%, respectively. The correlation coefficient (R2) of CNPs-EuNPs-FQLFIA or CNPs-QDs-FQLFIA to measure the different concentrations of ToxAbs spiked serum samples was 0.99712 and 0.99896, respectively. The CNPs-FQLFIA presented a characteristics of 94.3% sensitivity, 100% specificity and 98% accuracy for detection of ToxAbs in clinical serum samples. In conclusion, CNPs-FQLFIA with EuNPs or QDs fluorescence reporter was an easy, rapid, sensitive, precise and quantitative assay for detecting Tox antibodies in human blood samples.

Systematic Review and Meta-Analysis of Congenital Toxoplasmosis Diagnosis: Advances and Challenges

Objective

To understand how congenital toxoplasmosis (CT) diagnosis has evolved over the years, we performed a systematic review and meta-analysis to summarize the kind of analysis that has been employed for CT diagnosis.

Methods

PubMed and Lilacs databases were used in order to access the kind of analysis that has been employed for CT diagnosis in several samples. Our search combined the following combining terms: "congenital toxoplasmosis" or "gestational toxoplasmosis" and "diagnosis" and "blood," "serum," "amniotic fluid," "placenta," or "colostrum." We extracted data on true positive, true negative, false positive, and false negative to generate pooled sensitivity, specificity, and diagnostic odds ratio (DOR). Random-effects models using MetaDTA were used for analysis.

Results

Sixty-five articles were included in the study aiming for comparisons (75.4%), diagnosis performance (52.3%), diagnosis improvement (32.3%), or to distinguish acute/chronic infection phases (36.9%). Amniotic fluid (AF) and placenta were used in 36.9% and 10.8% of articles, respectively, targeting parasites and/or T. gondii DNA. Blood was used in 86% of articles for enzymatic assays. Colostrum was used in one article to search for antibodies. In meta-analysis, PCR in AF showed the best performance for CT diagnosis based on the highest summary sensitivity (85.1%) and specificity (99.7%) added to lower magnitude heterogeneity.

Conclusion

Most of the assays being researched to diagnose CT are basically the same traditional approaches available for clinical purposes. The range in diagnostic performance and the challenges imposed by CT diagnosis indicate the need to better explore pregnancy samples in search of new possibilities for diagnostic tools. Exploring immunological markers and using bioinformatics tools and T. gondii recombinant antigens should address the research needed for a new generation of diagnostic tools to face these challenges.

Could PLATELIA Toxo IgM be the new gold standard for the serological diagnosis of congenital toxoplasmosis: a French multicenter study

To assess the performance of PLATELIA Toxo IgM (Bio-Rad) and Toxo ISAGA (BioMérieux) to detect anti-Toxoplasma IgM in infants at risk of congenital toxoplasmosis, a retrospective multicenter study was conducted comparing serological results obtained in the framework of routine diagnosis work-up for congenital toxoplasmosis. All infants born to mothers infected with T. gondii during pregnancy from 2010 to 2020 with at least 6 months of serological follow-up were included (n = 1,010). One thousand ten cases were included, of which 250 infants (24.75%) had congenital toxoplasmosis. A total of 1039 sera were included. The concordance between the two techniques was 96%, with kappa coefficient of 0.87, showing an almost perfect agreement between ISAGA and PLATELIA. Cumulative sensitivity and specificity were 73.2% and 99.5.% and 74.8% and 100% for ISAGA and PLATELIA, respectively. The mean time to detect IgM using ISAGA and PLATELIA tests was 6.9 ± 20.1 days and 5.6 ± 14.7 days, respectively not significant (ns). Finally, the sensitivity of ISAGA and PLATELIA to detect IgM antibodies in infected neonates at 5 days of life was 62% and 64%, respectively. Performances of PLATELIA Toxo IgM assay were comparable to the gold standard ISAGA. This enzyme-linked immunosorbent assay is suitable for routine serology for the diagnosis of congenital toxoplasmosis in newborns. IMPORTANCE This study will help clinical microbiologists to chose an alternative serological method for the neonatal diagnosis of congenital toxoplasmosis, once the gold standard technique ISAGA will be withdrawn next year.

Comparative performance of ISAGA IgM and ELISA assays for the diagnosis of maternal and congenital Toxoplasma infections: which technique could replace ISAGA IgM?

The ISAGA immunocapture test for the detection of anti-Toxoplasma immunoglobulin M is a manual technique known for its excellent sensitivity and specificity. The purpose of this retrospective, multicenter study was to compare the performances and agreement between ISAGA and other IgM detection techniques before cessation of ISAGA production. The analytic performance of the different tests was evaluated using 1,341 serum samples from adults with positive IgM and negative IgG to Toxoplasma gondii, and 1,206 sera from neonates born to mothers with seroconversion. The agreement between the tests was evaluated on 13,506 adult and 5,795 child serum samples. The sensitivity of Toxo-ISAGA IgM® (adults 98.7%, neonates 63.1%) was similar to that of Platelia Toxo IgM® (adults 94.4%, neonates 64.6%), and significantly higher than Liaison Toxo IgM® (adults 90.6%), Architect/Alinity Toxo IgM® (adults 95.7%, neonates 48.6%), and Vidas Toxo IgM® (adults 81.8%, neonates 17.5%). However, the specificities varied between 24.4% (Platelia Toxo IgM®) and 95.2% (Liaison Toxo IgM®) in adults and were >95% for all tests in neonates. An analysis of the kappa coefficients showed better agreement between ISAGA IgM® and the other tests in children (0.75-0.83%) than in adults (0.11-0.53%). We conclude that, in the absence of Toxo-ISAGA IgM®, the association of a very sensitive technique (Platelia Toxo IgM® or Architect/Alinity Toxo IgM®) and a very specific technique (Vidas Toxo IgM® or Liaison Toxo IgM®) is recommended for IgM detection in adult sera. For neonates, Platelia Toxo IgM® appeared to be the best alternative to replace Toxo-ISAGA IgM®.

Diagnosis of Congenital Toxoplasmosis: Challenges and Management Outcomes

Introduction Congenital toxoplasmosis (CT), despite being mostly subclinical at birth, can cause disabling disease in the fetus and lead to long-term sequelae. It is an important cause of chorioretinitis in infants and adolescents. Data on postnatal treatment are controversial, and there is a lack of universal guidelines. Methods A cross-sectional study of newborns with suspected CT was conducted between January 2007 and December 2021. Results Seventy-one patients with suspected CT were included. During pregnancy, 64 (90.1%) of the mothers underwent therapy, of which 59 (83.1%) with spiramycin. Amniocentesis identified one positive polymerase chain reaction assay. Most newborns were asymptomatic with normal laboratory, ophthalmological, and hearing screening. There was one case of hyperproteinorrachia. Fifty-seven patients (80.3%) started treatment: 42 (73.7%) with spiramycin, seven (12.3%) with pyrimethamine, sulfadiazine, and folinic acid (P+S+FA), and eight (14%) with P+S+FA intercalated with spiramycin. Adverse effects were found in 11 (19.3%) cases, mainly neutropenia. After investigation, we found three confirmed CT cases corresponding to 4.2% of suspected cases and an incidence of 0.4 per 10,000 births. All had normal clinical and laboratory exams in the neonatal period and started P+S+FA, fulfilling 12 months of therapy. During the follow-up, all presented normal psychomotor development without any long-term sequelae. Conclusion The lower incidence in our study, compared to the incidence in Europe, may be related to the decline in the prevalence of toxoplasmosis as well as the effectiveness of measures to prevent primary infection and a well-established program of antenatal screening, followed by the early initiation of treatment during pregnancy to prevent vertical transmission.

Contribution of serology in congenital toxoplasmosis diagnosis: results from a 10-year French retrospective study

This study aimed to evaluate different serological strategies for the postnatal diagnosis of congenital toxoplasmosis (CT) and establish a biological algorithm for CT diagnosis. The study analyzed serological data of immunoglobulins M, A, and G (IgM, IgA, IgG) performed by immunoenzymatic and compared immunological profile (CIP) assays in 668 newborns with CT diagnosis across four testing periods: P1 (D0- D10), P2 (D11-D35), P3 (D36-D45), and P4 (>D45). Forty-nine percent of the 668 CT cases were diagnosed during P1 and 34%, 4%, and 12% during P2, P3, and P4, respectively. CIP assays detected neosynthetized IgMs/IgGs in 98% of CT cases diagnosed during P1, while IgMs and IgAs were detected in 90% and 57% of CT cases diagnosed during P2 and in 88% and 67% of diagnoses made during P3, respectively. Detection of neosynthesized IgMs/IgGs, IgMs, and IgAs by immunoassay contributed to CT diagnosis in 81%, 77%, and 60% of cases, respectively. In total, 46% of serum samples were positive for all three parameters, 27% for two, and 27% for one of the three. The study recommends using the CIP assay as standard during P1 for CT diagnosis and IgM and IgA immunoassays after P1. A clinical and biological follow-up in a specialized center with a close collaboration between biologists and clinicians is highly recommended to increase the chances of early diagnosis. Overall, this study provides useful information for the development of a biological algorithm for CT diagnosis, which can aid in early detection and appropriate treatment of this disease.

Congenital Toxoplasmosis Diagnosis: Current Approaches and New Insights

PURPOSE

The aim of this study is to describe and discuss current disadvantages in congenital toxoplasmosis (CT) diagnosis, and what can be improved or changed through new perspectives and technological advances.

METHODS

We used Pubmed, Cochrane, and EBSCO databases to research publications from 10 years to date describing current diagnostic methods for CT. The keywords used for this Mini-Review were Toxoplasma gondii, congenital toxoplasmosis, diagnosis, and prospects using Boolean operators such as AND, OR, identifying scientific publications highlighting the importance of implementing new diagnostic methods.

RESULTS

Current diagnosis methods have several disadvantages, i.e., time-consuming, low sensitivity or specificity, and non-cost effective, that bring up the necessity of improving or developing new approaches. Recombinant proteins can help improve specificity by generating tests that use circulating strains in a specific geographical region, SAG1 and BAG1, as they are expressed during a particular stage of the disease (acute or chronic, respectively), for its use in serological diagnoses, such as capture ELISA and immunochromatography. Point of Care (POC) tests are methods performed at the patient care site, which leads to rapid patient treatment; despite the advantages, several improvements and perspectives are necessary to be implemented globally.

CONCLUSIONS

Although already established diagnosis methods for CT may be sufficient in some regions, there is still a persistent demand to develop tests with higher throughput, cost, and time reduction in developing countries, where prevalence is high. New approaches in CT diagnosis, such as recombinant proteins, capture ELISA, immunochromatography, and POC tests methods, can increase performance in terms of specificity and sensitivity simplifying diagnostic tests' requirements.

Real-time PCR in the diagnosis of congenital toxoplasmosis

The diagnosis of congenital toxoplasmosis presents limitations and therefore new options are necessary. The analysis of amniotic fluid by real-time PCR has already proved effective for confirmation of fetal infection. However, its performance in other biological samples is not clear yet. The aim of this study is to better understand the role of real-time PCR in the blood of the mother and newborn as well as in the amniotic fluid and placenta in the diagnosis of congenital toxoplasmosis. This is a descriptive cohort study of pregnant women with toxoplasmosis followed up in Rio de Janeiro, Brazil. Real-time PCR was performed in samples of maternal blood, amniotic fluid, placenta, and blood of newborns. In addition, histopathological examination of placentas was performed, and data collected from babies were collected. 116 pregnant women were followed up and 298 samples were analyzed. One (0.9%) pregnant woman presented positive PCR in the blood, 3 (3.5%) in the amniotic fluid, 1 (2.3%) in the placenta and no newborn had positive PCR in the blood. Histopathological study was suggestive of toxoplasmosis infection in 24 (49%) placentas. Six (5.2%) newborns were diagnosed with congenital toxoplasmosis, and only cases with positive PCR in the amniotic fluid had correlation of the PCR result with the diagnosis of congenital infection. Both maternal and blood samples of newborns and placenta did not prove to be promising in the diagnosis of congenital toxoplasmosis. Further studies are needed to evaluate the real role of molecular diagnosis in other biological materials rather than the amniotic fluid.

Toxoplasmosis Screening during Pregnancy in a Romanian Infectious Diseases Tertiary Center: Results of a 15 Years Follow-Up Program

Maternal infection with Toxoplasma gondii during pregnancy may have serious consequences for the fetus. In Romania, screening for toxoplasmosis is included in the first antenatal visit. A retrospective study was performed on all toxoplasmosis antenatal screening patients between May 2008 and February 2023. Twenty-seven thousand one hundred sixty-nine (27,169) pregnant women presented for prenatal screening once (22,858) or several times: during the same pregnancy (209) or during multiple pregnancies (4102). Thirty-one thousand six hundred fifty-eight (31,658) tests for IgM and IgG antibodies were performed. Nine thousand eighty-three (9083) tests (28.69%), corresponding to 7911 women (29.12%), were positive for IgG antibodies. The seroprevalence increased with patients' age, decreased in time intervals, and was more frequently associated with rural residence. At risk for acquiring the infection during the pregnancy were women with negative anti-Toxoplasma IgG antibodies (70.88%), but only 0.9% of them presented for rescreening during the same pregnancy. Acute Toxoplasma infection (ATI) was suspected in 44 patients (0.16%) due to IgG seroconversion and/or low or borderline IgG avidity. A questionnaire follow-up interview was performed, and no congenital toxoplasmosis was identified in children born from mothers with probable ATI. Our study demonstrates poor compliance with the screening program in the Romanian population.

A zirconia-based column chromatography system optimized for the purification of IgM from hybridoma culture supernatants

By using EDTPA-modified zirconia particles that selectively adsorb immunoglobulins in a column, we developed a chromatography separation system for efficient concentrating and purifying of IgM from hybridoma culture supernatants. Hybridoma culture supernatants containing IgMs were diluted 3-fold with 10 mM phosphate buffer (pH 7.0) and passed through the column. During this process, zirconia particles selectively adsorbed these IgMs, and most of the contaminating proteins flowed out into the flow-through. The adsorbed IgMs were easily eluted with a small volume of 400 mM phosphate buffer (pH 8.0), and high-concentration IgM solutions were prepared. Subsequent simple processing using a Capto™ Core 400 cartridge column provided highly purified IgM. The operation is easy, and the activity of IgM is maintained because the purification process is performed using only neutral ranges of phosphate buffers. Here, we showed that anti-globoside and anti-CDw75 IgM purified by this method can be used to stain cervical cancer and Burkitt lymphoma cells that specifically express these respective tumor-associated carbohydrate antigens.

Diagnosis of Congenital Toxoplasmosis: Performance of Four IgG and IgM Automated Assays at Birth in a Tricentric Evaluation

For postnatal diagnosis of congenital toxoplasmosis (CT), the gold standard for the detection of anti- Toxoplasma IgM in newborns relies on the immunosorbent agglutination assay (ISAGA), which is manufactured from whole Toxoplasma parasites that become difficult to maintain. For IgG, only the Platelia assay provides a validated assay for cord blood according to the manufacturer, allowing its use in this context.

Diagnosis of Congenital Toxoplasmosis: No Benefit of IgA Antibody Detection by Platelia ELISA in a Tricentric Evaluation

The diagnostic accuracy of a commercial Toxoplasma gondii IgA antibody enzyme-linked immunosorbent assay (ELISA) was evaluated in the context of routine practice on 289 newborns with congenital toxoplasmosis (CT) and 220 healthy controls. The performance of this assay was compared to that of the current gold-standard test for anti- Toxoplasma IgM detection, an immunosorbent agglutination assay (ISAGA).

Comparative Performance of Recombinant GRA6, GRA7, and GRA14 for the Serodetection of T. gondii Infection and Analysis of IgG Subclasses in Human Sera from the Philippines

Highly specific and sensitive diagnostic methods are vital for the effective control and treatment of toxoplasmosis. Routine diagnosis is primarily serological because T. gondii infections stimulate persistently high IgG antibody responses. The sensitivity and specificity of methods are crucial factors for the proper diagnosis of toxoplasmosis, primarily dependent on the antigens used in different assays. In the present study, we compared the serodiagnostic performances of three recombinant dense granule antigens, namely, the GRA6, GRA7, and GRA14, to detect IgG antibodies against T. gondii in human sera from the Philippines. Moreover, we evaluated the IgG1, IgG2, IgG3, and IgG4 responses against the different recombinant antigens, which has not been performed previously. Our results revealed that the TgGRA7 has consistently displayed superior diagnostic capability, while TgGRA6 can be a satisfactory alternative antigen among the GRA proteins. Furthermore, IgG1 is the predominant subclass stimulated by the different recombinant antigens. This study's results provide options to researchers and manufacturers to choose recombinant antigens suitable for their purpose.

Efficiency of a Single well IgG, IgM and IgA Anti T. gondii Fluorimetric Assay for Pre-natal Screening for Congenital Toxoplasmosis

Toxoplasmosis, worldwide protozoan disease, is usually benign, except when acute disease occurs in pregnant women, resulting in fetal infection with deaths or high morbidity after birth. Treatment blocks fetal infection or damage after infection, imposing a quick and effective diagnosis. Maternal infection is mostly asymptomatic thus regular serology are the main tool for detect seroconversion and acute infection in prenatal care. Screening test for specific anti T. gondii IgG, IgM and IgA must be quick, cheaper and available for the prenatal care. Fluorescent solid phase assays appears as a good alternative as they allow one well detection of IgG and IgM aside to allow high throughput in 384 wells. Here, we standardize and analyze a single well anti-T. gondii IgG, IgM and IgA immunosorbent fluorescent assay in a large sample of a public hospital. We construct conjugates for each immunoglobulin with specific fluorophores, which allows concomitant detection in a microplate fluorimeter, with stability and reproducibility, allowing cheaper 384 wells use. Tested in our 600 mother samples from a large public hospital, they presented the same reactivity as standard routine tests, but with adequate IgM and IgA screening, as adequately standardized in house ELISA, while the design of most commercial assays give false positive results. The few TFISA positive IgG, IgM and IgA samples also had low avidity IgG, confirming recent infection. TFISA will help a screening toxoplasmosis in pregnancy program in large cities, with , allowing testing large numbers of samples at low cost and must be considered for other serological purposes.

Congenital Toxoplasmosis: The State of the Art

Infection with the protozoan parasite Toxoplasma gondii occurs worldwide and usually causes no symptoms. However, a primary infection of pregnant women, may infect the fetus by transplacental transmission. The risk of mother-to-child transmission depends on week of pregnancy at the time of maternal infection: it is low in the first trimester, may reach 90% in the last days of pregnancy. Inversely, however, fetal disease is more severe when infection occurs early in pregnancy than later. Systematic serologic testing in pregnant women who have no antibodies at the beginning of pregnancy, can accurately reveal active maternal infection. Therefore, the risk of fetal infection should be assessed and preventive treatment with spiramycin must be introduced as soon as possible to reduce the risk of mother-to-child transmission, and the severity of fetal infection. When maternal infection is confirmed, prenatal diagnosis with Polymerase Chain Reaction (PCR) on amniotic fluid is recommended. If fetal infection is certain, the maternal treatment is changed to a combination of pyrimethamine-sulfonamide and folinic acid. Congenitally infected newborns are usually asymptomatic at birth, but at risk for tardive sequelae, such as blindness. When congenital infection is evident, disease include retinochoroiditis, cerebral calcifications, hydrocephalus, neurocognitive impairment. The diagnosis of congenital infection must be confirmed at birth and management, specific therapy, and follow-up with multidisciplinary counseling, must be guaranteed.

Evaluation of Toxoplasma gondii recombinant antigens for early diagnosis of congenital toxoplasmosis

The performance of Toxoplasma rGra8, rMic1, and the chimeric rGra4-Gra7 antigens for early congenital toxoplasmosis (CT) diagnosis was evaluated. Sera from CT patients showed high IgG reactivity to rMic1, rGra8, and rGra4-Gra7. The seroreactivity of samples from uninfected infants was lost within 2 months of age.

Identification of Oocyst-Driven Toxoplasma gondii Infections in Humans and Animals through Stage-Specific Serology-Current Status and Future Perspectives

The apicomplexan zoonotic parasite Toxoplasma gondii has three infective stages: sporozoites in sporulated oocysts, which are shed in unsporulated form into the environment by infected felids; tissue cysts containing bradyzoites, and fast replicating tachyzoites that are responsible for acute toxoplasmosis. The contribution of oocysts to infections in both humans and animals is understudied despite being highly relevant. Only a few diagnostic antigens have been described to be capable of discriminating which parasite stage has caused an infection. Here we provide an extensive overview of the antigens and serological assays used to detect oocyst-driven infections in humans and animals according to the literature. In addition, we critically discuss the possibility to exploit the increasing knowledge of the T. gondii genome and the various 'omics datasets available, by applying predictive algorithms, for the identification of new oocyst-specific proteins for diagnostic purposes. Finally, we propose a workflow for how such antigens and assays based on them should be evaluated to ensure reproducible and robust results.

Geo-climatic factors and prevalence of chronic toxoplasmosis in pregnant women: A meta-analysis and meta-regression

In this study, we evaluated the effects of geo-climatic parameters and other potential risk factors on the prevalence of chronic toxoplasmosis (CT) in pregnant women. We searched PubMed/MEDLINE, Web of Science, EMBASE, Scopus, and SciELO databases for seroepidemiological studies published between January 1988, and February 2021. We performed meta-analysis and meta-regression by using a random effect model to synthesize data. A total of 360 eligible datasets, including 1,289,605 pregnant women from 94 countries, were included in this study. The highest and lowest prevalence rates were estimated for latitudes of 0-10° (49.4%) and ≥50° (26.8%); and for the longitude of 80-90° (44.2%) and 110-120° (7.8%), respectively. Concerning climatic parameters, the highest and lowest prevalence rates were estimated in regions with the mean relative humidities of >80% (46.6%) and <40% (27.0); annual precipitation between 1000 and 1500 mm (39.2%) and 250-500 mm (26.8%); and mean annual temperature of 20-30 °C (36.5%), and <7 °C (24.9%), respectively. Meta-regression analyses indicated significant increasing trends in prevalence of CT in pregnant women with decrease in geographical latitude (coefficient, = -0.0035), and geographical longitudes (C = -0.0017). While it was positively associated (P < 0.01) with the mean environmental temperature (C = 0.0047), annual precipitation (C = 0.000064), and mean relative humidity (C = 0.002). Our results highlighted various effects of environmental parameters on the prevalence of CT. Therefore, different regions in the world may benefit from different types of interventions, and thus, novel preventive measures in a region should be developed according to local climate, agricultural activities and people culture.

Late Diagnosis of Congenital Toxoplasmosis with Macrocephaly in Dizygotic Twins after Incidental Detection of Leukocoria: A Case Report

Untreated congenital toxoplasmosis remains an important cause of neurologic and ocular disease worldwide. However, congenitally infected infants may not have signs and symptoms their physicians recognize, leading to delayed diagnosis and missed opportunities for treatment. We describe a pair of twins diagnosed with congenital toxoplasmosis at 11 months of age following incidental detection of leukocoria in one twin.

Coordinated action of multiple transporters in the acquisition of essential cationic amino acids by the intracellular parasite Toxoplasma gondii

Intracellular parasites of the phylum Apicomplexa are dependent on the scavenging of essential amino acids from their hosts. We previously identified a large family of apicomplexan-specific plasma membrane-localized amino acid transporters, the ApiATs, and showed that the Toxoplasma gondii transporter TgApiAT1 functions in the selective uptake of arginine. TgApiAT1 is essential for parasite virulence, but dispensable for parasite growth in medium containing high concentrations of arginine, indicating the presence of at least one other arginine transporter. Here we identify TgApiAT6-1 as the second arginine transporter. Using a combination of parasite assays and heterologous characterisation of TgApiAT6-1 in Xenopus laevis oocytes, we demonstrate that TgApiAT6-1 is a general cationic amino acid transporter that mediates both the high-affinity uptake of lysine and the low-affinity uptake of arginine. TgApiAT6-1 is the primary lysine transporter in the disease-causing tachyzoite stage of T. gondii and is essential for parasite proliferation. We demonstrate that the uptake of cationic amino acids by TgApiAT6-1 is ‘trans-stimulated’ by cationic and neutral amino acids and is likely promoted by an inwardly negative membrane potential. These findings demonstrate that T. gondii has evolved overlapping transport mechanisms for the uptake of essential cationic amino acids, and we draw together our findings into a comprehensive model that highlights the finely-tuned, regulated processes that mediate cationic amino acid scavenging by these intracellular parasites.

The causative agent of toxoplasmosis, Toxoplasma gondii, is a versatile intracellular parasite that can proliferate within nucleated cells of warm-blooded organisms. In order to survive, T. gondii parasites must scavenge the cationic amino acids lysine and arginine from their hosts. In a previous study, we demonstrated that a plasma membrane-localized protein called TgApiAT1 facilitates the uptake of arginine into the parasite. We found that parasites lacking TgApiAT1 could proliferate when cultured in medium containing high concentrations of arginine, suggesting the existence of an additional uptake pathway for arginine. In the present study, we demonstrate that this second uptake pathway is mediated by TgApiAT6-1, a protein belonging to the same solute transporter family as TgApiAT1. We show that TgApiAT6-1 is the major lysine transporter of the parasite, and that it is critical for parasite proliferation. Furthermore, we demonstrate that TgApiAT6-1 can transport arginine into parasites under conditions in which arginine concentrations are high and lysine concentrations are comparatively lower. These data support a model for the finely-tuned acquisition of essential cationic amino acids that involves multiple transporters, and which likely contributes to these parasites being able to survive and proliferate within a wide variety of host cell types.

Toxoplasma gondii infection and spontaneous abortion: A systematic review and meta-analysis

Toxoplasmosis is one of the most common parasitic infections in humans, which is caused by Toxoplasma gondii. It is usually asymptomatic but primary infection in a pregnant woman can cause severe consequences in the fetus such as miscarriage. This study aimed to estimate the global prevalence of T. gondii infection in women with spontaneous abortion. It also evaluates the possible relationship between recent Toxoplasma infection and miscarriage. Five electronic databases were reviewed. We used the random effects model and 95% confidence intervals(CI) to determine the overall prevalence and odds ratio (OR). Heterogeneity was calculated using Cochran's Q test and I² statistic. The included studies were divided into three sub-groups based on antibody class against T. gondii and the existence of parasite DNA. Based on PCR, the pooled random-effects estimates that the prevalence of T. gondii infection in women with abortion was 10% (95% CI 7-14%). The pooled random effect favored a statistically significant increased risk of latent Toxoplasma infection [OR = 1.84; 95% CI: 1.41-2.40, P < 0.001] and recent infection [OR = 3.72; 95% CI: 2.21-6.26, P < 0.001] in women with spontaneous abortions. In recent infections, significant pooled ORs of positive association were observed in women with miscarriage [OR = 4.2; 95% CI: 2.04-8.85; χ2 = 17.2; I² = 42.0%, P = 0.07]. This study demonstrates that recent T. gondii infection is associated with an elevated risk of spontaneous abortion. Further studies concerning all risk factors related to toxoplasmosis, and undertaking confirmatory tests at the time of abortion should be performed to investigate the impact of T. gondii infection and spontaneous abortion.

M, Ladrón De Guevara M, Guzmán G, de la Guardia V, García A, Lucero MF, Wong D, Mcleod R, Soberon M, Caballero E. Z. Epidemiological Aspects of Maternal and Congenital Toxoplasmosis in Panama

In Panama, epidemiological data on congenital toxoplasmosis are limited, making it difficult to understand the scope of clinical manifestations in the population and factors that may increase the risk of infection. This study provides insight into the epidemiological situation of maternal and congenital toxoplasmosis in Panama and contributing information on the burden of this disease in Central America. Blood samples were collected from 2326 pregnant women and used for the detection of anti-T. gondii antibodies. A high seroprevalence (44.41%) was observed for T. gondii infection in pregnant women from different regions of Panama, with an estimated incidence rate of congenital toxoplasmosis of 3.8 cases per 1000 live births. The main risk factors associated with T. gondii infection using bivariate statistical analysis were an elementary level education and maternal age range of 34-45 years. Multivariate statistical analyses revealed that in some regions (San Miguelito, North and West regions), the number of positive cases correlated with the presence of pets, stray dogs and the consumption of poultry. In other regions (East and Metropolitan regions), the absence of pets was considered a protective factor associated with negative cases, while the presence of stray cats and the age range of 25-34 years did not represent any risk in these regions.

Identification of Biomarkers for Diagnosis and Prognosis of Congenital and Acute Toxoplasmosis

BACKGROUND

The diagnosis of congenital toxoplasmosis can be inconclusive in many cases. Despite the several serological tests developed, the literature on biomarkers that can assist in the diagnosis of congenital an acute toxoplasmosis is limited. The objective of this study was to analyze the immunoreactive profile of Toxoplasma gondii protein bands with the potential to be biomarkers for diagnosis and prognosis of congenital and acute toxoplasmosis.

METHODS

Peripheral blood samples from women of childbearing age and/or pregnant women diagnosed with acquired toxoplasmosis as well as from congenitally infected children were selected and submitted to immunoblotting for analysis of the immunoreactive bands profile by immunoglobulin G (IgG) antibodies.

RESULTS

When comparing the immunoreactive bands profile for antibodies present in samples from different groups and subgroups, the 150, 18.5, and 16.96-kDa bands were more immunoreactive with the antibodies present in serum samples from the acquired infection group. The 343, 189, 150, 75, and 42-kDa bands showed more chance to be detected by the symptomatic congenital infection subgroup samples, while the 61, 50, and 16.96-kDa bands were significantly immunoreactive with the acute infection subgroup samples.

CONCLUSIONS

The identification of these potential biomarkers can assist in early diagnosis and treatment of congenital toxoplasmosis.

The Role of microRNAs in the Infection by T. gondii in Humans

MicroRNAs are molecules belonging to an evolutionarily conserved family of small non-coding RNAs, which act on post-transcriptional gene regulation, causing messenger RNA (mRNA) degradation or inhibiting mRNA translation into proteins. These molecules represent potential biomarkers for diagnosis, non-invasive prognosis, and monitoring the development of the disease. Moreover, they may provide additional information on the pathophysiology of parasitic infections and guide strategies for treatment. The Apicomplexan parasite Toxoplasma gondii modifies the levels of microRNAs and mRNAs in infected host cells by modulating the innate and adaptive immune responses, facilitating its survival within the host. Some studies have shown that microRNAs are promising molecular markers for developing diagnostic tools for human toxoplasmosis. MicroRNAs can be detected in human specimens collected using non-invasive procedures. changes in the circulating host microRNAs have been associated with T. gondii infection in mice and ocular toxoplasmosis in humans. Besides, microRNAs can be amplified from samples using sensitive and molecular-specific approaches such as real-time PCR. This review presents recent findings of the role that microRNAs play during T. gondii infection and discuss their potential use of these small nuclei acid molecules to different approaches such as laboratory diagnosis, modulation of cell and tissue infected as other potential applications in human toxoplasmosis.

Immunodiagnosis and molecular validation of Toxoplasma gondii-recombinant dense granular (GRA) 5 protein for the detection of toxoplasmosis in hemodialysis patients

Toxoplasmosis causes serious complications in immunocompromised and pregnant women. Serological tests for the detection of toxoplasmosis are often designed from parasitic tachyzoites antigens. The process of producing these antigens is very difficult. The purpose of this study was evaluation of T. gondii-rGRA5 for the immunodiagnosis and molecular detection of Toxoplasma infection using enzyme-linked immunosorbent assay (ELISA) and LAMP methods in hemodialysis patients. The GRA5 gene was successfully expressed and purified by affinity chromatography assay and evaluated by western blot. Then it was used to design an ELISA assay. A total of 260 samples were tested for anti-Toxoplasma IgG and IgM antibodies using a commercial ELISA kit and designed ELISA kit. Finally, the LAMP method was used to evaluate the precision and reliability of the results obtained by commercial and designed ELISA kits. The consistency of the results of two methods was analyzed using the Kappa coefficient of agreement. The rGRA5 revealed higher immunoreactivity with 1:100 dilution of sera from toxoplasmosis patients. The specificity and sensitivity of the assay were 93% and 96%, respectively. According to the Kappa coefficient, there was a substantial correlation between the results of ELISA and LAMP based on rGRA5 (≈98%, p < 0.001). Also it showed that rGRA5 protein can be used as an antigenic protein for designing sero-diagnostic tests to identify Toxoplasma infection especially in hemodialysis patients.

A First Report on Experience in Managing Infants with Congenital Toxoplasmosis in Ethiopia: Case Reports and a Review of Evaluation and Treatment

Background. Congenital toxoplasmosis is a major sequela of untreated primary maternal infection. With or without symptoms, untreated infections eventually lead to multiple neurologic complications. Despite the high Toxoplasma gondii seroprevalence in the Ethiopian population, there are no reports of newborns diagnosed and treated for congenital toxoplasmosis. Presentation of Cases. The clinical presentation, evaluation, and management of three infants with congenital toxoplasmosis are described. Two were symptomatic at birth. All three had confirmed diagnoses using Toxoplasma serologic tests. Two completed their treatment with one infant developing complications of strabismus and seizure disorder. Discussion and Conclusions. There is little experience in managing congenital toxoplasmosis in Ethiopia due to constraints in diagnostics and therapy. The description of this first such report underscores the need for risk assessment and evaluation during antenatal care to obtain favorable fetal outcomes.

Bilateral ocular involvement in congenital toxoplasmosis: A case report and literature review

We report a case of neuro-ophthalmological complications of congenital toxoplasmosis, a parasitic infection caused by Toxoplasma gondi. Its congenital form occurs either as a primary infection or as reactivation of the same due to immunosuppression during pregnancy. With an incidence rate of 1.5/1000 live births, this disease is an important cause of visual loss from chorio-retinal lesions in >82%. Recent studies have shown that treatment given in utero and in the first year of life can reduce ophthalmological complications.

Maternal Anti-Toxoplasma Treatment during Pregnancy Is Associated with Reduced Sensitivity of Diagnostic Tests for Congenital Infection in the Neonate

Neonatal diagnosis of congenital toxoplasmosis is based on a combination of serological and molecular tests. Maternal screening and treatment differ according to national policies and may impact the sensitivity of diagnostic methods in infants at birth. In this multicenter study, 115 neonates born to 61 treated (53%) and 54 (47%) untreated women were retrospectively included in three centers (France, Serbia, and the United States) to assess the impact of maternal anti-Toxoplasma treatment on the performance of neonatal workup at birth (neosynthesized anti-Toxoplasma IgM, IgA, and IgG and quantitative PCR [qPCR]) using univariate and multivariate approaches. Independently of the time of maternal seroconversion, the serological techniques were impacted differently by maternal treatment. The detection of IgM by immunosorbent agglutination assay (ISAGA) and Western blotting (WB) dropped from 90.7% and 88.2% in untreated neonates to 53.3% and 51.9% in treated neonates (P < 0.05), whereas IgM enzyme-linked immunosorbent assay (ELISA) and IgA ISAGA were not significantly affected by maternal treatment. A 2-fold reduction in the sensitivity of neosynthesized IgG by WB was also observed in the case of treatment during pregnancy (37.7% versus 82.3%). Interestingly, the effect of treatment was shown to be duration dependent, especially for IgM detection, when the treatment course exceeded 8 weeks, whatever the therapy. The sensitivity of Toxoplasma PCR in blood was also lowered by maternal treatment from 39.1% to 23.2%. These results highlight that anti-Toxoplasma therapy during pregnancy may set back biological evidence of neonatal infection at birth and underline the need for a careful serological follow-up of infants with normal workup.

Putative biomarkers for early diagnosis and prognosis of congenital ocular toxoplasmosis

In the present study we have evaluated the performance of several immunological biomarkers for early diagnosis and prognosis of congenital toxoplasmosis. Our results showed that ex vivo serum levels of CXCL9, and the frequencies of circulating CD4⁺CD25⁺ T-cells and T. gondii-specific IFN-γ⁺CD4⁺ T-cells measured 30–45 days after birth presented high accuracy to distinguish T. gondii-infected infants from healthy age-matched controls (Global Accuracy/AUC = 0.9; 0.9 and 0.8, respectively). Of note was the enhanced performance (Accuracy = 96%) achieved by using a combined stepwise analysis of CD4⁺CD25⁺ T-cells and CXCL9. In addition, high global accuracy (AUC = 0.9) with elevated sensitivity (Se = 98%) was also reached by using the total frequency of in vitro IFN-γ-producing T. gondii-specific T-cells (∑ IFN-γ⁺ CD4⁺ & CD8⁺) as a biomarker of congenital toxoplasmosis. Furthermore, the analysis of in vitro T. gondii-specific IL5⁺CD4⁺ T-cells and IFN-γ⁺NK-cells displayed a high accuracy for early prognosis of ocular lesion in infant with congenital toxoplasmosis (Global Accuracy/AUC = 0.8 and 0.9, respectively). Together, these findings support the relevance of employing the elements of the cell-mediated immune response as biomarkers with potential to endorse early diagnosis and prognosis of congenital ocular toxoplasmosis to contribute for a precise clinical management and effective therapeutic intervention.

Asymmetric eye size in an infant

Toxoplasmosis is an uncommon congenital infection in Canada, but one with potentially severe clinical manifestations, including fetal death. Neurologic and ocular manifestations are frequent in untreated disease; however, small eye size (microphthalmia) is a rare finding. This finding may be a marker of severe ocular disease. As universal screening does not occur in Canada, clinicians' early recognition is imperative, particularly given the lack of risk factors in many patients and the benefit that treatment may have even in initially asymptomatic disease. Here, we report a case of congenital toxoplasmosis and review the diagnostics and treatment of the infection.

Fifteen-minute consultation: Management of the infant born to a mother with toxoplasmosis in pregnancy

Congenital toxoplasmosis occurs following transplacental transfer of Toxoplasma gondii Irrespective of symptom status at birth, infants with congenital infection may develop serious long-term sequelae, including learning disability, seizures, hydrocephalus, motor and hearing deficits, chorioretinitis and retinal scarring with impaired vision. Timely diagnosis facilitates early initiation of therapy, aimed at prevention or amelioration of adverse clinical consequences. Diagnosis can be difficult, however, since acutely infected mothers are often asymptomatic and laboratory testing can be complex. Moreover, any decision to start treatment in the newborn must include careful consideration of the benefits and risks. This paper outlines a structured approach for managing an infant born to a woman with possible or confirmed T. gondii infection during pregnancy, including key aspects of the antenatal history, interpretation and timing of investigations, treatment and appropriate follow-up. Our recommendations are based on current evidence in the literature, consensus from two UK paediatric infectious disease centres and the UK specialist Toxoplasma Reference Unit.

Age-related changes in cerebral congenital toxoplasmosis: Histopathological and immunohistochemical evaluation

Congenital toxoplasmosis is a widespread worldwide disease producing varying degrees of damage to the fetus including ocular and neurological impairment. However, the underlying mechanisms are not yet clear. Therefore, the current study aimed to investigate the progress of congenital cerebral toxoplasmosis in experimentally infected offspring animal model at different age groups till become adults. To fulfill this aim, the offspring of Me49 T. gondii infected pregnant mice were divided into groups; embryo, infant, young and adult phases. Blood and brain samples were collected for further hormonal and histopathological studies and immunohistochemical staining of glial fibrillary acidic protein (GFAP) and synaptophysin (SYN). Our results showed several encephalitic changes in the infected groups ranging from gliosis to reduced cortical cell number and fibrinoid degeneration of the brain. We showed increased expression of GFAP and SYN indicating activation of astrocytes and modification of the synaptic function, respectively. These changes started intrauterine following congenital infection and increased progressively afterward. Moreover, infected mice had elevated corticosterone levels. In conclusion, the current study provided new evidences for the cellular changes especially in the infected embryo and highlighted the role of GFAP and SYN that may be used as indicators for T. gondii-related neuropathy.

Toxoplasmosis in Germany

BACKGROUND

With approximately 30% of the world population infected, Toxoplasma gondii is one of the most widespread pathogenic parasites in both humans and animals and a major problem for health economics in many countries.

METHODS

This review is based on the findings of individual studies, meta-analyses, and Cochrane Reviews retrieved by a selective literature survey of the Medline and Google Scholar databases.

RESULTS

Current data indicate a high rate of Toxoplasma gondii infection in Germany, ranging from 20% to 77% depending on age (95% confidence interval for 18- to 29-year-olds [17.0; 23.1]; for 70- to 79-year-olds [72.7; 80.5]). Male sex, caring for a cat, and a body mass index of 30 or more are independent risk factors for seroconversion. Postnatally acquired (food-related) infec- tion is predominant, but maternal-to-fetal transmission still plays an important role. While most infections are asymptomatic, congenital toxoplasmosis and reactivated Toxoplasma encephalitis in immunosuppressed persons (transplant recipients and others) are sources of considerable morbidity. Toxoplasma gondii infection of the retina is the most common cause of infectious uveitis in Germany. The diagnosis and treatment of this type of parasitic infection are particular to the specific organs involved in the individual patient.

CONCLUSION

Desirable steps for the near future include development of an effective treatment for the cystic stage and identifica- tion of biomarkers to assess the risk of reactivation and predict the disease course.

Review on the Current Trends of Toxoplasmosis Serodiagnosis in Humans

Toxoplasmosis is a widely distributed zoonotic infection caused by the obligate intracellular apicomplexan parasite Toxoplasma gondii. It is mainly transmitted through the ingestion of oocysts shed by an infected cat acting as its definitive host. The key to effective control and treatment of toxoplasmosis is prompt and accurate detection of T. gondii infection. Several laboratory diagnostic methods have been established, including the most commonly used serological assays such as the dye test (DT), direct or modified agglutination test (DAT/MAT), indirect hemagglutination test (IHA), latex agglutination test (LAT), indirect immunofluorescent test (IFAT), enzyme-linked immunosorbent assays (ELISA), immunochromatographic tests (ICT), and the western blot. Nonetheless, creating specific and reliable approaches for serodiagnosis of T. gondii infection, and differentiating between acute and chronic phases of infection remains a challenge. This review provides information on the current trends in the serodiagnosis of human toxoplasmosis. It highlights the advantages of the use of recombinant proteins for serological testing and provides insight into the possible future direction of these methods.

Serological diagnosis of Toxoplasma gondii: analysis of false-positive IgG results and implications

BACKGROUND

Primary infection by Toxoplasma gondii in pregnant women can result in serious outcomes for the foetus. A false-positive IgG result during pregnancy can lead to a misdiagnosis of past infection and to stopping preventive measures. We collected 189 sera with positive Architect® Toxo IgG assay (Abbott Laboratories) and negative IgG results with at least two other serological tests, in order to find an explanation for the suspected false-positive IgG results. We used the recomLine Toxoplasma IgG® immunoblot (Mikrogen Diagnostik) to search for specific antigenic reactivities of the sera, and the LDBio Toxo II IgG® immunoblot (LDBio Diagnostics) as a confirmatory test.

RESULTS

The bands GRA8 and/or GRA7 were positive for 148 samples (78.3%). GRA8 was the most frequent band, appearing in 133 patterns (70.4%), whereas GRA7 was present for 49 samples (25.9%). Of the 81 samples tested with LDBio®, 23 (28.4%) turned out to be positive. Of the 58 negative LDBio® tests (71.6%) (real false-positive Architect® IgG), 23 samples (39.6%) did not show either a GRA8 or p30 band by recomLine®. Their false positivity with Architect® remains unexplained since Abbott uses these two recombinant antigens for their assay.

CONCLUSIONS

The Architect® IgG false positivity for T. gondii seems to be due to reactivity against GRA8 for the majority of the sera and GRA7 to a lesser extent. The hypothesis of past contact with parasites genetically close to T. gondii such as Hammondia hammondi or Neospora caninum seems promising and should be assessed further.

How to estimate time of infection with Toxoplasma gondii in pregnant women. Use of specific IgG and IgM kinetics by 7 techniques on 691 sera

A difficulty when detecting both anti-Toxoplasma gondii-specific IgG and IgM in pregnant women is estimating the date of infection. The aim of this study was to compare the anti-Toxoplasma-specific immunoglobulin kinetics of 7 serological techniques to date the infection and to draw kinetic curves that are easy to use on a daily basis. IgG and IgM antibodies were measured on 691 sera samples. IgM appeared a few days, less than 1 week, after the beginning of the infection. Then, the levels of IgM reached a peak at approximately 3, 4, and 5 weeks with Toxo-ISAGA® IgM, IgM homemade indirect immunofluorescence assays, and Vidas Toxo® IgM, respectively. Furthermore, the Architect Toxo® IgG titers were higher than those of the Vidas Toxo® IgG results in recent infection (less than 6 months). This study provides new average IgM and IgG curves that can help to determine the approximate date of infection.

Congenital Toxoplasmosis Presenting as Eosinophilic Encephalomyelitis With Spinal Cord Hemorrhage

A 4-week-old male neonate with a history of intermittent hypothermia in the newborn nursery presented with an acute onset of bilateral lower extremity paralysis and areflexia. Extensive workup demonstrated eosinophilic encephalomyelitis and multifocal hemorrhages of the brain and spinal cord. Funduscopic examination revealed bilateral chorioretinitis with macular scarring. The laboratory values were notable for peripheral eosinophilia and cerebrospinal fluid eosinophilic pleocytosis (28 white blood cells/µL, 28% eosinophils), markedly elevated protein (1214 mg/dL), and hypoglycorrhachia (20 mg/dL). Toxoplasma gondii immunoglobulin M (IgM) test result was positive. Reference testing obtained at the Palo Alto Medical Foundation Toxoplasma Serology Laboratory confirmed the diagnosis of congenital toxoplasmosis in the infant with a positive immunoglobulin G (IgG) dye test result, immunoglobulin A enzyme-linked immunosorbent assay, and IgM immunosorbent agglutination assay. The diagnosis of an infection acquired during gestation in the mother was established by a positive maternal IgG dye test result, IgM enzyme-linked immunosorbent assay, immunoglobulin A, immunoglobulin E, and low IgG avidity. At 6-month follow-up, the infant had marginal improvement in his retinal lesions and residual paraplegia with hyperreflexia and clonus of the lower extremities. A repeat MRI demonstrated interval development of encephalomalacia with suspected cortical laminar necrosis and spinal cord atrophy in the areas of previous hemorrhage. Clinicians should be aware of this severe spectrum of congenital toxoplasmosis disease and should remain vigilant for subtler signs that may prompt earlier testing, diagnosis, and treatment.

Global prevalence of latent toxoplasmosis in pregnant women: a systematic review and meta-analysis

BACKGROUND

Toxoplasma gondii infection, if acquired as an acute infection during pregnancy, can have substantial adverse effects on mothers, fetuses and newborns. Latent toxoplasmosis also causes a variety of pathologies and has been linked to adverse effects on pregnancy.

OBJECTIVE

Here, we present results of a comprehensive systematic review and meta-analysis of the global prevalence of latent toxoplasmosis in pregnant women.

DATA SOURCE

We searched PubMed, EMBASE, Web of Science, SciELO and Scopus databases for relevant studies that were published between 1 January 1988 and 20 July 2019.

STUDY ELIGIBILITY CRITERIA

All population-based, cross-sectional and longitudinal studies reporting the prevalence of latent toxoplasmosis in healthy pregnant women were considered for inclusion.

PARTICIPANTS

Pregnant women who were tested for prevalence of latent toxoplasmosis.

INTERVENTIONS

There were no interventions.

METHOD

We used a random effects model to calculate pooled prevalence estimates with 95% confidence intervals (CIs). We grouped prevalence data according to the geographic regions defined by the World Health Organization (WHO). Multiple subgroup and meta-regression analyses were performed.

RESULTS

In total, 311 studies with 320 relevant data sets representing 1 148 677 pregnant women from 91 countries were eligible for inclusion in the meta-analysis. The global prevalence of latent toxoplasmosis in pregnant women was estimated at 33.8% (95% CI, 31.8-35.9%; 345 870/1 148 677). South America had the highest pooled prevalence (56.2%; 50.5-62.8%) of latent toxoplasmosis in pregnant women, whereas the Western Pacific region had the lowest prevalence (11.8%; 8.1-16.0%). A significantly higher prevalence of latent toxoplasmosis was associated with countries with low income and low human development indices (p < 0.001).

CONCLUSION

Our results indicate a high level of latent toxoplasmosis in pregnant women, especially in some low- and middle-income countries of Africa and South America, although the local prevalence varied markedly. These results suggest a need for improved prevention and control efforts to reduce the health risks to women and newborns.

Acute Toxoplasma infection in pregnant women worldwide: A systematic review and meta-analysis

BACKGROUND

Acute Toxoplasma infection (ATI) during pregnancy, if left untreated, can cause severe adverse outcomes for the fetus and newborn. Here, we undertook a meta-analysis to estimate the worldwide prevalence of ATI in pregnant women.

METHODS

We searched international databases for studies published between January 1988 and November 2018. We included population-based cross-sectional and prospective cohort studies that reported the prevalence of ATI in pregnant women. Data were synthesized using a random effect model to calculate the overall prevalence of ATI (with a 95% CI) in six WHO regions and globally. We also performed linear meta-regression analyses to investigate associations of maternal, socio-demographic, geographical and climate parameters with the prevalence of ATI.

RESULTS

In total, 217 studies comprising 902,228 pregnant women across 74 countries were included in the meta-analysis. The overall prevalence of ATI in pregnant women globally was 1.1% (95% CI: 0.9-1.2%). In studies where more strict criteria for ATI were used, the overall prevalence was 0.6% (95% CI: 0.4-0.7%). The prevalence was highest in the Eastern Mediterranean region (2.5%; 95%CI: 1.7-3.4%) and lowest in the European region (0.5%; 95% CI: 0.4-0.7%). A significantly higher prevalence of ATI was found in countries with lower income levels (P = 0.027), lower human development indices (P = 0.04), higher temperatures (P = 0.02) and lower latitudes (P = 0.005) and longitudes (P = 0.02).

CONCLUSIONS

The risk of acquiring ATI during gestation is clinically important and preventive measures to avoid exposure of pregnant women to Toxoplasma infection should be strictly applied.

Live Attenuated Pru:Δcdpk2 Strain of Toxoplasma gondii Protects Against Acute, Chronic, and Congenital Toxoplasmosis

Background

The threat of Toxoplasma gondii infection in immunocompromised individuals and pregnant women necessitates the development of a safe and effective vaccine. Here, we examined the immune protection conferred by a live attenuated strain of T. gondii.

Methods

We tested the efficacy of intraperitoneal vaccination using 500 Ca2+-dependent protein kinase 2 (cdpk2)-deficient tachyzoites of T. gondii Pru strain against acute, chronic, and congenital toxoplasmosis in mice. The kinetics of antibody response, cytokines, and other quantifiable correlates of protection against T. gondii infection were determined.

Results

Vaccination with Pru:Δcdpk2 induced a high level of anti-T. gondii immunoglobulin G titer, type 1 T-helper (Th1) response at 28 days postvaccination, and a mixed Th1/type 2 T-helper response at 70 days postvaccination. All vaccinated mice survived a heterologous challenge with 1000 tachyzoites of RH or ToxoDB#9 (PYS or TgC7) strains. Also, vaccination protected against homologous infection with 20 T. gondii Pru cysts, and improved pregnancy outcome by reducing parasite cyst load in the brain, maintaining litter size and body weight of pups born to vaccinated dams challenged with 10 Pru cysts compared to pups born to unvaccinated dams.

Conclusions

The use of T. gondii Pru:Δcdpk2 mutant strain represents a promising approach to protection against acute, chronic, and congenital toxoplasmosis in mice.

Enhancing the detection of Toxoplasma gondii via an anti-SAG1 scFv-alkaline phosphatase immunoconjugate

The purpose of this study was to implement a fluorometric method for enhancing the detection sensitivity of Toxoplasma gondii in biological fluids. To address this challenge, we designed and produced a recombinant immunoconjugate tool based on a single-chain antibody fragment anti-T. gondii SAG1 antigen (scFvSG15) genetically fused to the bacterial alkaline phosphatase (AP) using 4-methyl-umbelliferyl-phosphate as fluorogenic substrate. The anti-SAG1 scFv-AP conjugate was fully bifunctional and was used successfully in different assays including immunoblot, fluorometric ELISA and direct immunofluorescence. The fluorometric immunoassay afforded an extremely low detection limit (1 tachyzoite/well), which was in agreement with the real-time PCR control test. The immunofluorescence imaging has provided captivating visual evidence of T. gondii detection. These results strongly suggest that the recombinant anti-SAG1-AP conjugate generated here might serve as useful and highly sensitive immunoassay probe to direct detect T. gondii in a one-step procedure, opening up new perspectives for diagnosis of toxoplasmosis.

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.

Detection of Anti-Toxoplasma gondii Antibodies in Human Sera Using Synthetic Glycosylphosphatidylinositol Glycans on a Bead-Based Multiplex Assay

Toxoplasmosis, while often an asymptomatic parasitic disease in healthy individuals, can cause severe complications in immunocompromised persons and during pregnancy. The most common method to diagnose Toxoplasma gondii infections is the serological determination of antibodies directed against parasite protein antigens. Here we report the use of a bead-based multiplex assay containing a synthetic phosphoglycan portion of the Toxoplasma gondii glycosylphosphatidylinositol (GPI1) for the detection of GPI1-specific antibodies in human sera. The glycan was conjugated to beads at the lipid site to retain its natural orientation and its immunogenic groups. We compared the response against GPI1 with that against the protein antigen SAG1, a common component of commercial serological assays, via the detection of parasite-specific human IgG and IgM antibodies, respectively. The GPI1-based test is in excellent agreement with the results for the commercial ELISA, as the ROC analysis of the GPI1 test shows 97% specificity and 98% sensitivity for the assay. GPI1 was a more reliable predictor for a parasite-specific IgM response compared to SAG1, indicating that a bead-based multiplex assay using GPI1 in combination with SAG1 may strengthen Toxoplasma gondii serology, in particular in seroepidemiological studies.

Infections in pregnancy

Infections in pregnancy represent a challenging and often underappreciated area of concern for many specialists and general practitioners and can cause serious sequelae. Antenatal status should be highlighted on pathology request forms, as this serves to alert the laboratory of the need to store serum for an extended period. Prior antenatal specimens can be forwarded to other laboratories to enable testing in parallel with the more recent sample. Women with a confirmed, potentially vertically transmissible infection should be referred to a specialist with expertise in the management of perinatal infections. Cytomegalovirus infection is the most common congenital infection. Women who care for young children are at greater risk of exposure to the virus. Preventive steps including hand hygiene and avoiding contact with children's urine, mucous and saliva are recommended for all pregnant women. The incidence of parvovirus B19 infection in pregnancy is unknown. This infection is highly contagious and may result in fetal loss; particularly in the first half of pregnancy, pregnant women should avoid contact with adults or children who may have an infection.

Performance of a Multiplex Nested Polymerase Chain Reaction in Detecting 7 Pathogens Containing DNA in Their Genomes Associated With Congenital Infections

CONTEXT.—

Infections are the leading cause of perinatal and infant mortality in low-income and low-resource countries, which have a higher prevalence of infections. Definitive diagnosis of congenital and perinatal infections is largely dependent upon the results of laboratory tests.

OBJECTIVE.—

To develop a multiplex nested polymerase chain reaction (PCR) technique for the simultaneous detection of 7 pathogens containing DNA in their genomes in suspected cases of congenital infection.

DESIGN.—

Eligible participants were pregnant women with positive immunoglobulin M antibodies raised to one of the pathogens in the prenatal serologic screening, associated or not with fetal ultrasound abnormalities or positive fetal serology. Neonates whose mothers did not attend prenatal care were included when they presented with symptomatology and laboratory parameters suggestive of infection. The detection rate of the multiplex nested PCR was compared with maternal, fetal, and neonatal serology, as well as placental immunohistochemistry and noncommercial amplifications.

RESULTS.—

Of 161 suspected cases, the multiplex nested PCR detected 60 (37.3%), whereas the tests available in hospital laboratories detected 13 of 60 (21.7%) of the cases detected by the multiplex nested PCR, demonstrating a 4.6 times higher detection rate for the multiplex nested PCR (Fisher exact test, P < .001). Positive amplifications were to Toxoplasma gondii (32 cases), cytomegalovirus (14 cases), parvovirus B19 (5 cases), and adenovirus (5 cases). In 4 cases, 2 pathogens were simultaneously detected. All types of biological matrices were suitable for amplification. Sequencing of multiplex nested PCR products confirmed the molecular findings.

CONCLUSIONS.—

The multiplex nested PCR significantly increased the number of diagnosed congenital infections. Given the scarcity of DNA recovered from amniotic fluid and some neonatal samples, this multiplex nested PCR allows the simultaneous detection of 7 pathogens associated with congenital infections in a reliable, faster, cost-effective, and more sensitive way.