Hervé Pelloux

Toxoplasma gondii infection is usually asymptomatic in immunocompetent individuals. However, primary infection during pregnancy can lead to severe fetal manifestations. Consequently, accurate diagnosis of maternal infection is essential for prompt treatment. Currently, diagnosis mainly relies on detection of anti- T . gondii specific IgM and IgG in serum. If detection of IgM can be indicative of acute infection, it may also reflect the presence of persistent or non-specific antibodies. The Toxo-ISAGA IgM assay (bioMérieux, France), formerly considered a gold standard for anti- T . gondii IgM detection, was discontinued in 2024. New and reliable assays are, therefore, needed to support risk assessment and clinical decision-making, particularly in maternal and neonatal settings. A new generation of the VIDAS TOXO IgM assay (bioMérieux, France), one of the most commonly used commercially available assays for the detection of anti- T. gondii specific IgM in serum, has recently been developed: the VIDAS TXMN assay (reference 424641). This study aimed at evaluating its clinical performance. A retro-prospective study was conducted in two French clinical parasitology–mycology laboratories in 2024. Performance was determined on 1,275 single sera from patients with recent or chronic postnatal Toxoplasma infection and non-infected patients and on serial serum samples from both women who seroconverted during pregnancy and neonates with and without congenital Toxoplasma infection. In addition, qualitative results were compared to those obtained with frequently used commercially available comparators and ISAGA. Sensitivity and specificity of the VIDAS TXMN assay were 98.77 (95% confidence interval [CI]: 93.31–99.97%) and 100.00% (95% CI: 99.59–100.00%), respectively. It allowed earlier detection of IgM than the previous generation assay both in pregnant women and in newborns from mothers who seroconverted during pregnancy. In addition, agreements with the Architect Toxo IgM (Abbott Diagnostics), Platelia Toxo IgM (Bio-Rad), and Toxo-ISAGA (bioMérieux) were almost perfect (Cohen’s kappa > 0.85). The new VIDAS TXMN assay improved the detection of anti- T. gondii -specific IgM in serum compared to the previous generation and displayed high agreement with commercially available comparators and ISAGA. It, therefore, appears to reliably contribute to the diagnosis of maternal and congenital toxoplasmosis. IMPORTANCE: Toxoplasma gondii is an ubiquitous parasite, which can cause severe fetal damage when first contracted in a pregnant woman. Serology—and particularly the detection of anti- T. gondii -specific IgM antibodies—plays a key role in diagnosing recent infections and, therefore, contributes to appropriate management of pregnant women and newborns. Commercial availability of anti- T. gondii -specific IgM assays has recently evolved, with the discontinuation of the Toxo-ISAGA IgM assay (bioMérieux, France) as a gold standard and the marketing of a new version of the VIDAS TOXO IgM assay (bioMérieux, France). This study first establishes the performance of this new assay for diagnosing maternal and congenital infections, with a direct comparison with other commonly used commercial assays. This evaluation is essential for ensuring reliable diagnosis and supporting clinical decision-making, particularly in maternal and neonatal settings.

The diagnosis of congenital toxoplasmosis or disseminated toxoplasmosis in immunocompromised patients nowadays relies on molecular tools, in particular real-time PCR. There are many reagents on the market, and their evaluation by independent experts provides valuable information to medical biologists who are looking for a high-performance kit among the different references. Under the aegis of the French National Reference Center for Toxoplasmosis, we report here a multicenter evaluation of the analytical and clinical performances of the “quanty TOXO (RH region)” PCR assay manufactured by Clonit. The kit showed good analytical performance, as indicated by the results of serial dilution tests and external quality control samples. PCR efficiencies varied from 95% to 105%; linearity zone extended over four log units ( R ² >0.99), and limit of detection varied from <1 parasite/mL to between 1 and 5 parasites/mL, i.e., from <0.08 parasite/PCR to between 0.2 and 1 parasite/PCR, depending on the center. Based on 141 cryopreserved DNAs from a large range of clinical specimens, we determined a clinical sensitivity of 94.7% (71/75; 95% confidence interval [CI]: 87.1%–97.9%) and a clinical specificity of 100% (66/66; 95% CI: 94.5%–100%). Four false negative results were detected despite amplification carried out in duplicate. Overall, the “quanty TOXO (RH region)” PCR assay demonstrated satisfactory analytical and clinical performances for the diagnosis of toxoplasmosis, even using extraction and amplification techniques or biological matrices not validated by the manufacturer. IMPORTANCE: Due to its speed and accuracy, PCR is now the gold standard for diagnosing congenital and disseminated toxoplasmosis. High-performance molecular testing is essential, especially for immunocompromised patients and congenital infections, to initiate early treatment. This diagnostic approach increasingly relies on commercial assays. However, commercially available kits do not guarantee performance. In this study, conducted by the French National Reference Center for Toxoplasmosis, we performed an independent multicenter evaluation of the “quanty TOXO (RH region)” PCR assay manufactured by Clonit. Our results showed that this kit delivered satisfactory results for routine diagnostic use. However, among the 141 clinical samples tested, four false negative results were noted, corresponding to specimens with low parasitic load.

The high sensitivity of the automated tests used for Toxoplasma gondii serology can yield false-positive IgM results due to aspecific reactions. On the other hand, specific therapy can delay IgG production and, therefore, the diagnosis of seroconversion. There is a need for confirmation tests to early detect seroconversions during pregnancy. We conducted a multicentre study to evaluate the diagnostic accuracy of the Toxo II IgG and a new, not yet commercialised Toxo II IgM western blot (WB) (LDBio diagnostics Lyon France) on 229 sera corresponding to 93 patients with seroconversions and 158 sera corresponding to 68 patients with nonspecific IgM. Sensitivity was 97.8% for IgM WB and 98.9% for IgG WB. Specificity was 89.7% and 100%, respectively. The concordance between IgM and IgG Toxo WB with the final diagnosis was very good, K = 0.89 and K = 0.99, respectively. In 5 cases (5.4%), the appearance of IgM, and in 55 cases (59.1%), the appearance of IgG was recorded by WB earlier than by traditional tests. In 10 cases (10.8%), IgM was detected after the traditional tests and in 2 cases (2.2%) for IgG. The association of IgG and IgM WB on the same sample not only detected all seroconversions but also correctly identified most of the false-positive results.

Sleepiness is the main clinical expression of obstructive sleep apnea (OSA) syndrome resulting from upper airway collapse. Recent studies have discussed the fact that the presence of T. gondii cysts in the brain and the resulting biochemical and immunological mechanisms could be linked to neurobehavioral disorders. The aim of the present study was to explore the potential impact of chronic toxoplasmosis on sleepiness and on obstructive sleep apnea (OSA) severity in OSA obese patients. A case control study on obese patients screened for OSA was performed. According to the sleep disorder and matched based on gender, age and body mass index (BMI), two groups of obese patients were selected from our sample collection database. All patients were tested for toxoplasmosis serological status measuring anti-Toxoplasma IgG and IgM levels. Univariable and multivariable logistic regression models were performed to assess the impact of chronic toxoplasmosis on sleepiness and OSA severity. 107 obese patients suffering from OSA were included in the study (median age: 53.3 years Interquartile range (IQR): [41.9–59.9]; median BMI: 39.4 kg/m² IQR: [35.5–44.1], apnea-hypopnea index = 27.5 events/h [10.7–49.9]). Chronic toxoplasmosis was present in 63.4% and 70.7% of patients with or without sleepiness (p = 0.48), respectively and was not associated either to sleepiness (OR: 0.76, 95% CI: [0.52; 2.33], p = 0.64) or OSA severity (OR = 1.75, 95% CI: [0.51; 5.98] p = 0.37). Although chronic Toxoplasma infection in immunocompetent humans has been associated to several behavioral disorders or pathologies in recent literature, we demonstrate here that chronic toxoplasmosis is not associated to sleepiness and to sleep apnea syndrome severity in obese patients suspected of sleep apnea syndrome.

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. 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) 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). 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. The prototype performed comparably to the ARCHITECT^® and VIDAS^® Toxo IgM assays for the diagnosis of maternal and congenital toxoplasmosis.

We aimed to evaluate the usefulness of biological investigations in cases of eosinophilia in our area (French Alps). We retrospectively included all adult patients attending the infectious disease and internal medicine units between 2009 and 2015 with eosinophilia ≥1 G/l. We identified 298 cases (129 women and 169 men). In 139 patients, eosinophilia had not been addressed. In the 159 others, the cause of eosinophilia was identified in 118 (74.2%). The main identified causes at the time were drug reactions (24.5%, mostly β-lactams and allopurinol), infectious diseases (17.0%), vasculitis (8.2%), autoimmune diseases (6.9%), and malignant diseases (6.2%). In patients with a skin rash, eosinophilia was significantly more often investigated, and a diagnosis significantly more often made. Helminthosis were mainly diagnosed in tropical travelers (18/24) excepting toxocariasis (3 non-travelers). Stool examination for helminthosis was positive in 5/76 patients (6.6%) (all tropical travelers); 391 helminth serologies were performed in 91 patients, with 7.9% being positive (all but 3 positive cases were travelers). Anti-neutrophil cytoplasmic antibodies (ANCA) were positive in 26/112 patients (23.2%), with 9 cases of vasculitis identified. Drug-related eosinophilia is the main etiology. Search for helminthosis is not recommended among non-travelers (excepting toxocariasis). ANCA should be performed early so as not to overlook vasculitis.

Transplantation activity is increasing, leading to a growing number of patients at risk for toxoplasmosis. We reviewed toxoplasmosis prevention practices, prevalence, and outcomes for hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT; heart, kidney, or liver) patients in Europe. We collected electronic data on the transplant population and prevention guidelines/regulations and clinical data on toxoplasmosis cases diagnosed during 2010–2014. Serologic pretransplant screening of allo-hematopoietic stem cell donors was performed in 80% of countries, screening of organ donors in 100%. SOT recipients were systematically screened in 6 countries. Targeted anti-Toxoplasma chemoprophylaxis was heterogeneous. A total of 87 toxoplasmosis cases were recorded (58 allo-HSCTs, 29 SOTs). The 6-month survival rate was lower among Toxoplasma-seropositive recipients and among allo-hematopoietic stem cell and liver recipients. Chemoprophylaxis improved outcomes for SOT recipients. Toxoplasmosis remains associated with high mortality rates among transplant recipients. Guidelines are urgently needed to standardize prophylactic regimens and optimize patient management.