Help in the Choice of Automated or Semiautomated Immunoassays for Serological Diagnosis of Toxoplasmosis: Evaluation of Nine Immunoassays by the French National Reference Center for Toxoplasmosis.

Toxoplasmosis, a benign infection, is asymptomatic or paucisymptomatic in over 80% of cases, except in immunocompetent patients suffering from ocular toxoplasmosis or in immunocompromised patients with opportunistic or congenital toxoplasmosis. Diagnosis is based mainly on serology testing. Thus, we compared the performance of the nine most commonly used commercial automated or semiautomated immunoassays for IgG and IgM Toxoplasma gondii antibody detection, that is, the Advia Centaur, Architect, AxSYM, Elecsys, Enzygnost, Liaison, Platelia, VIDAS, and VIDIA assays. The assays were conducted on four panels of serum samples derived during routine testing from patients with an interfering disease and who exhibited a low IgG antibody level in one of two clinical settings, namely, acute or chronic toxoplasmosis. As a result, IgG sensitivities ranged from 97.1% to 100%, and IgG specificities ranged from 99.5% to 100%. For IgG quantification, strong differences in IgG titers (expressed in IU/ml) were noted depending on the assay used. IgM sensitivities ranged from 65% to 97.9%, and IgM specificities ranged from 92.6% to 100%. For defining the best serological strategies to be implemented, it appears crucial to compare the diagnostic performance of the different tests with respect to their specificity and sensitivity in detecting the presence of IgG and IgM antibodies.

Serological diagnosis of Toxoplasma gondii infection: Recommendations from the French National Reference Center for Toxoplasmosis.

Toxoplasmosis manifests no clinical signs in 80% of cases in immunocompetent patient, causing immunization characterized by the persistence of cysts, particularly in brain, muscles, and retina. Assessing the serological status, based on testing for serum toxoplasma IgG and IgM antibodies, is essential in cases that are increasingly at risk for the more severe disease forms, such as congenital or ocular toxoplasmosis. This disease also exposes immunosuppressed patients to reactivation, which can lead to more widespread forms and increased mortality. By interpreting the serological results, we can estimate the risk of contamination or reactivation and define appropriate prophylactic and preventive measures, such as hygienic and dietetic, therapeutic, biological, and clinical follow-up, according to the clinical context. We hereby propose practical approaches based on serological data, resulting from a consensus of a group of experts from the French National Reference Center Network for Toxoplasmosis, according to both routine and specific clinical situations.

[Severe congenital toxoplasmosis secondary to toxoplasma reactivation in an HIV-infected mother]. / Toxoplasmose congénitale sévère secondaire à une réactivation toxoplasmique chez une mère infectée par le VIH.

Congenital toxoplasmosis is a potentially serious fetal infection associated with maternal seroconversion or a reactivation of toxoplasmosis during pregnancy. We report the case of congenital toxoplasmosis with severe neurological injury with normal prenatal obstetric ultrasounds in a mother infected with HIV at the AIDS stage and previously immunized against toxoplasmosis.

Toxoplasma seroconversion with negative or transient immunoglobulin M in pregnant women: myth or reality? A French multicenter retrospective study.

Classically, Toxoplasma infection is associated with high levels of specific IgM antibody and a rise in specific IgG levels 1 to 3 weeks later. Atypical IgG seroconversion, without IgM detection or with transient IgM levels, has been described during serologic follow-up of seronegative pregnant women and raises difficulties in interpreting the results. To evaluate the frequency and the characteristics of these atypical cases of seroconversion, an investigation was conducted within the French National Reference Center for Toxoplasmosis, from which 26 cases collected from 12 laboratories belonging to the network were identified. The aim of this work was to retrospectively analyze the results of serologic testing, the treatments administered, and the results of prenatal and postnatal follow-up for these women. In each case, IgG antibodies were detected using both screening and confirmatory tests. IgM antibodies were not detected in 15 cases, and the levels were equivocal or low-positive in 11 cases. The IgG avidity results were low in 16 cases and high in one case. Most of the pregnant women (22/26) were treated with spiramycin from the time that IgG antibodies appeared until delivery. Amniotic fluid was analyzed for Toxoplasma gondii DNA by PCR in 11/26 cases, and the results were negative in all cases. Congenital toxoplasmosis was ruled out in 12/26 newborns. There was no abnormality observed at birth for 10 newborns and no information available for 4 newborns. In conclusion, when the interpretation of serological results is so difficult, it seems cautious to initiate treatment by spiramycin and to follow the pregnant women and their newborns.

Comparison of four commercially available avidity tests for Toxoplasma gondii-specific IgG antibodies.

Toxoplasma infection in pregnant women may cause congenital toxoplasmosis. Diagnosis of infection is based on serological tests aimed at detecting IgM and IgG antibodies against Toxoplasma gondii. However, IgM antibodies are not an accurate marker for discriminating between acute and latent infection. Detection of residual or persistent IgM may occur months or even years after primary infection, while the IgG avidity test is a rapid means of identifying latent infections in pregnant women who exhibit both IgG and IgM anti-Toxoplasma antibodies on initial testing during pregnancy. In this study, we assessed and compared the performances of four commercially available Toxoplasma IgG avidity tests in immunocompetent and immunocompromised patients with acute and latent toxoplasmosis. The positive predictive value of high avidity to confirm latent toxoplasmosis was 100% for all the assays, indicating that high avidity is a hallmark of latent infection. However, the negative predictive value of high avidity ranged from 99.2% (bioMérieux) to 95.3% (Abbott), indicating that acute toxoplasmosis could not be reliably diagnosed based on low IgG avidity alone. Thus, the avidity test provides a rapid means for identifying latent Toxoplasma infection in immunocompetent pregnant women presenting both IgG and IgM anti-Toxoplasma antibodies on initial testing. In terms of cost-effectiveness, avidity testing is a powerful tool that optimizes screening and follow-up of pregnant women while minimizing the costs of screening by avoiding subsequent costly maternal and fetal investigation and unnecessary treatment. The cheapest assay, Vidas Toxo IgG Avidity, also had the best performance for the diagnosis of latent toxoplasmosis.

Black grain mycetoma caused by Leptosphaeria tompkinsii.

Leptosphaeria tompkinsii is a dematiaceous fungus which is rarely reported as an agent of black-grain mycetoma. We present a case involving a mycetoma of the hand of a former farmer from Mali, West Africa, who has been a resident in France for 27 years. The patient was successfully treated with surgery and the use of oral itraconazole for 6 months. Species identification was based on sexual reproductive structures observed on potato-carrot agar media and the use of internal transcribed spacer sequencing.

[Imported malaria in 2000 in 2 northern Paris hospitals]. / Le paludisme d'importation en 2000 dans deux hôpitaux du nord de la région parisienne.

The number of travellers in malaria striken areas increases each year (2). The risk of infection is high in Sub-Saharan Africa, but appropriate chemoprophylaxis can reduce the morbidity and mortality rate of malaria. Half of the samples of malaria cases received by the National reference centre of malaria chemosensibility (CNRCP) for chemosensibility analysis came from two hospitals in the north of Paris: Bichat Claude Bernard in Paris and Delafontaine in Saint-Denis. In 2000, quite all the malaria cases (n = 387) observed at the Bichat and Delafontaine Hospitals came from Africa (99%). Plasmodium falciparum remains the most represented (87.6%) species, with an average parasitic density of 0.3%. Patients with P falciparum came for medical advice on the tenth day after return (median, extremes 0-174 days). More than half of the patients (58%) did not take any medication for chemoprophylaxis and even if they took some, it was irregular or inappropriate. The most used drug chemoprophylaxis is the association of chloroquine and proguanil or Savarine. In 15% of the cases, the travellers took chloroquine as a prophylaxis and 4% other medicine not recommended by the French authorities. An average of 43.7% of these travellers took inappropriate chemoprophylaxis. In total, 27 chemoprophylaxis failures are reported. Some patients (22%) have already taken self treatment which was readjusted during admission at hospital. The first treatment of malaria in 2000 was monotherapy with quinine (P. falciparum) and chloroquine (P. ovale, malariae, vivax). The treatment associations in case of suspicious resistance were quinine + doxycycline and atovaquone + proguanil. Treatment failure was infrequent and resulted above all from a bad observance. More information should be given to travellers as well as doctors about recommendations and treatments.

Profile and evolution of the chemosusceptibility of falciparum malaria imported into France in 2000.

In 2000, the chemosusceptibility of imported malaria was stable in France. All countries of infection considered, the bi-resistance to chloroquine and cycloguanil has not changed from 1996 to 2000. The monotherapy using quinine or mefloquine remains the first-line treatment to falciparum malaria. Resistance to these two antimalarials is rare in Africa and has not evolved over the past 15 years.

[Resistance to chloroquine and cycloguanil of Plasmodium falciparum in patients arriving in France after travel in Africa without chemoprophylaxis]. / Résistance à la chloroquine et au cycloguanil de Plasmodium falciparum chez des patients arrivant en France après un voyage en Afrique sans chimioprophylaxie.

The in vitro susceptibility of chloroquine and the genomic profile of dihydrofolate reductase (DHFR) codon 108 was determined against african isolates of P. falciparum (Pf) from imported malaria cases without previous drug intake by an isotopic microtest or PCR + RFLP. Pf resistance to chloroquine or to the DHFR inhibitor was present in 49% and 46% of isolates, respectively. Pf drug resistance was more frequent in permanent than in seasonal malarial transmission areas and chloroquine plus DHFR resistance reached 28% in years 1995-97. Updating the guidelines for the prevention of malaria in travellers to Africa is necessary.