Spinal cord toxoplasmosis in a young immunocompetent patient.

We report a case of spinal cord toxoplasmosis occurring as a primary infection in a 31-year-old immunocompetent man. Exhaustive immunologic and genetic investigations did not identify any immunodeficiency. The causative agent was a typical type 2 strain. In cases of spinal cord lesions, toxoplasmosis should be considered, even in an immunocompetent patient.

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.

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.

[Management of ocular toxoplasmosis in France: Results of a modified Delphi study]. / Prise en charge de la toxoplasmose oculaire en France : résultats d'une étude Delphi modifiée.

OBJECTIVE: To evaluate diagnostic and therapeutic practices and then establish a consensus on the management of ocular toxoplasmosis in France through a Delphi study. MATERIALS AND METHODS: Twenty-three French experts in ocular toxoplasmosis were invited to respond to a modified Delphi study conducted online, in the form of two questionnaires, in an attempt to establish a consensus on the diagnosis and management of this pathology. The threshold for identical responses to reach consensus was set at 70 %. RESULTS: The responses of 19 experts out of the 23 selected were obtained on the first questionnaire and 16 experts on the second. The main elements agreed upon by the experts were to treat patients with a decrease in visual acuity or an infectious focus within the posterior pole, to treat peripheral lesions only in the presence of significant inflammation, the prescription of first-line treatment with pyrimethamine-azithromycin, the use of corticosteroid therapy after a period of 24 to 48hours, the prophylaxis of frequent recurrences (more than 2 episodes per year) with trimethoprim-sulfamethoxazole as well as the implementation of prophylactic treatment of recurrences in immunocompromised patients. On the other hand, no consensus emerged with regard to the examinations to be carried out for the etiological diagnosis (anterior chamber paracentesis, fluorescein angiography, serology, etc.), second-line treatment (in the case of failure of first-line treatment), or treatment of peripheral foci. CONCLUSION: This study lays the foundations for possible randomized scientific studies to be conducted to clarify the management of ocular toxoplasmosis, on the one hand to confirm consensual clinical practices and on the other hand to guide practices for which no formal consensus has been demonstrated.

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.

Loss of oral infectivity of tissue cysts of Toxoplasma gondii RH strain to outbred Swiss Webster mice.

We have developed a method for obtaining cysts of Toxoplasma gondii RH strain. Outbred Swiss Webster mice were infected subcutaneously (s.c.) or intraperitoneally (i.p) with 10(5) tachyzoites and given sulfadiazine 400 mg l-1 + NaHCO3 10 g l-1 in drinking water from day 1 to day 15 post-infection (p.i.). None of the mice infected i.p. survived, compared with 50% of the mice infected s.c. Cysts were detectable in the brain on day 45 p.i., and had ultrastructural features consistent with those of bradyzoites. However, these cysts were incapable of infecting mice via the oral route. In addition, immunofluorescence studies showed the persistence of P36 protein expression, indicating that the conversion to bradyzoites was incomplete.

Immune response in a murine model of congenital toxoplasmosis: increased susceptibility of pregnant mice and transplacental passage of Toxoplasma gondii are type 2-dependent.

We used a model of acquired toxoplasmosis to study the immune response in pregnant BALB/c mice (IL-4+/+) and in pregnant transgenic IL-4-deficient BALB/c mice (IL-4-/-) during acute toxoplasmosis. Female BALB/c mice were infected orally by 20 tissue cysts of the avirulent PRU strain of Toxoplasma gondii on day 11 of pregnancy. Splenocyte cultures were used to explore proliferative responses and cytokine production in vitro. Parasite loads were determined in the lungs on day 7 post-infection and in the brain on day 30 post-infection. After infection, cultured spleen cells from pregnant mice produced more IFN-gamma (a Type I cytokine) and more NO than non pregnant mice, and the Type 2 response (IL-4 and IL-10) was weak. Although this kind of immune response may be required for mice to recover from toxoplasmosis, pregnant mice were more susceptible to infection than non pregnant mice, as illustrated by a larger parasite load in lungs and brain. Pregnant IL-4-/- mice showed lower susceptibility to T. gondii infection and a lower materno-fetal transmission rate (24% vs. 53% infected fetuses) without increased production of Type I cytokines (IFN-gamma and NO). These data indicate that Type 2 response plays an important role in increasing mouse susceptibility to T. gondii infection during pregnancy and that IL-4 and pregnancy-associated substances increase the transplacental passage of T. gondii.

[Exploration of immune response in a murine model of congenital toxoplasmosis]. / Exploration de la réponse immune dans un modèle de toxoplasmose congénitale murin.

We used a model of acquired toxoplasmosis to study the immune response in pregnant BALB/c mice (IL4+/+) and in pregnant transgenic IL4-deficient BALB/c mice (IL4-/-) during acute toxoplasmosis. Female BALB/c mice were infected orally by 20 tissue cysts of the avirulent PRU strain of Toxoplasma gondii on day 11 of pregnancy. After infection, cultured spleen cells from pregnant mice produced more IFN gamma (a type 1 cytokine) and more NO than non pregnant mice, and the type 2 response (IL4 and IL10) was weak. Although this kind of immune response may be required for mice to recover from toxoplasmosis, pregnant mice were more susceptible to infection than non pregnant mice, as illustrated by a larger parasite load in lungs and brain. Pregnant IL4-/- mice showed lower susceptibility to T. gondii infection and a lower materno-fetal transmission rate (24% versus 53% infected fetus) without increased production of type 1 cytokines (IFN gamma and NO). These data indicate that type 2 response plays an important role in increasing mouse susceptibility to T. gondii infection during pregnancy and that IL4 and pregnancy-associated substances increase the transplacental passage of T. gondii. This is the first time that biased towards type 2 immune response induced by pregnancy was shown to increase susceptibility to T. gondii.

[Prevalence of toxoplasmosis in a population of pregnant women in Antananarivo (Madagascar)]. / Prévalence de la toxoplasmose dans une population de femmes enceintes à Tananarive (Madagascar).

The prevalence of Toxoplasma antibodies by ELISA was studied in Antananarivo area, in the Republic of Madagascar, among a population of 599 pregnant women. The overall prevalence is 83.5%. From the age of 19 years old, 75% of the pregnant women have already antitoxoplasma antibodies. The ethnic factor, the foods habits or the presence of a domestic cat do not seem to have an influence on prevalence of toxoplasmosis among the studied population.

[Coprological evaluation of refugees in Strasbourg between January 1986 and December 1990]. / Bilan coprologique des réfugiés à Strasbourg entre janvier 1986 et décembre 1990.

1,000 refugees living in Strasbourg have had a stoll parasitologic exam between 1986 and 1990. We have not retained results of South America and other areas of Asia subjects because of their scarce total number. Proportionally, the most numerous are the South East Asia Nationals (51.7%); followed by those from Middle East and Africa (20 and 15.5%) and more recently by those from East of Europe (5.2%). Their parasitic infestation's rate remains important (60.9%) but variable depending on their origin. Thus, people coming from Middle East and Africa are parasited mainly by protozoan, although those from South East Asia are parasited by helminths. It's interesant to notify that the prevalence of D. fragilis is ten times higher among East European people than in the common people.

[Role of systematic ophthalmological screening for congenital toxoplasmosis: epidemiological study of an Alsatian cohort from 1990 to 2011]. / Intérêt du dépistage ophtalmologique systématique de la toxoplasmose congénitale: étude d'une cohorte alsacienne entre 1990 et 2011.

INTRODUCTION: Ophthalmologic complications of congenital toxoplasmosis, such as retino-choroiditis, are particularly feared. Any child with confirmed congenital toxoplasmosis is systematically treated and followed regularly with multiple fundus examinations. The goal of our study is to describe the management and monitoring of a cohort of patients with congenital toxoplasmosis in Alsace, and the impact of this disease in terms of parental anxiety using a standardized questionnaire. MATERIALS AND METHODS: Our study recorded 35 children with congenital toxoplasmosis, born between 1990 and 2011 in Alsace. All patients were followed by an ophthalmologist. A standardized questionnaire concerning the experience of pregnancy and post-natal follow-up was administered to the parents. RESULTS: At birth, retinochoroiditis was detected in 2 of the 35 children, and only one child developed chorioretinitis detected during follow-up monitoring (follow-up ranged from 1 to 22 years). Brain abnormalities were noted in 3 children at birth; none of them have presented with chorioretinitis to this day. An average score of 15 out of 23 was found by our standardized questionnaire, reflecting significant anxiety due to congenital toxoplasmosis. DISCUSSION: Parental anxiety due to congenital toxoplasmosis is obvious, as demonstrated by our standardized questionnaire. Follow-up, directed by comprehensive pediatric examination at birth, including fundus examination, and good information on functional signs of ocular toxoplasmosis may improve screening, so as to avoid impact on visual function.

[Ocular toxoplasmosis: from pathophysiology to microbiological diagnosis]. / Toxoplasmose oculaire : de la physiopathologie au diagnostic microbiologique.

Toxoplasmosis is the most common cause of posterior uveitis in immunocompetent subjects: 30% of the world population may be affected, with wide variability. However, despite high seroprevalence, the incidence of ocular toxoplasmosis (OT) is limited to about 2% of infected patients; thus, about one million patients in France may be estimated to have active or cicatricial OT. Microbiological tools available to the clinician have considerably advanced over the last two decades, allowing the diagnosis of toxoplasmosis to be confirmed in the vast majority of suspected cases. Regardless of the route of infection (congenital or acquired), laboratory confirmation of OT plays a major role in the patient's management, particularly in atypical cases.

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.

[Development of murine models of ocular toxoplasmosis and preliminary results of ocular inflammatory transcriptome]. / Mise au point de modèles murins de toxoplasmose oculaire et premiers résultats de l'analyse du transcriptome inflammatoire.

BACKGROUND/PURPOSE: Toxoplasmosis is the most common cause of posterior uveitis in immunocompetent subjects. Taking into account the opposing needs of limiting parasite multiplication and minimizing tissue destruction, the infection imbalance most often involves CD4 and CD8 T lymphocytes that play the lead role in adaptive immunity to T. gondii. The aims of our study were to develop murine models of toxoplasmosis and to study the immune responses to the infection. METHODS: Two murine models were studied: (i) intravitreal injection of T. gondii (primary infection) and (ii) intraperitoneal inoculation at birth and reinfection by intravitreal injection. Clinical and histological data were determined. mRNA-cytokine levels were measured in ocular samples obtained from mice with toxoplasma chorioretinitis using RT-PCR. RESULTS: Intravitreal injection of T. gondii led to chorioretinitis. Primary infection was characterized by severe chorioretinitis when compared with reinfection. mRNA levels of IFN-gamma, TNF-alpha, and iNOS were increased in infected mice. DISCUSSION: TH1 cells may mitigate chorioretinitis by limiting T. gondii proliferation. Further studies are needed to explore ocular immune regulation. These primary results may open new in vivo therapeutic approaches.

Toxoplasma gondii-induced foetal resorption in mice involves interferon-gamma-induced apoptosis and spiral artery dilation at the maternofoetal interface.

The severity of congenital toxoplasmosis depends on the stage of the pregnancy at which infection takes place. Infection during the first trimester generally leads to miscarriage, through an unknown mechanism. Toxoplasma gondii infection is normally controlled by a strong Th1-type response with IFN-gamma production. To investigate the mechanisms of foetal resorption induced by T. gondii, pregnant Swiss-Webster mice were infected 1 day post coïtum with the avirulent Me49 strain. Mated recipients were examined at mid-gestation. Few parasites and no cytolytic effects were detected 10 days post coïtum in implantation sites undergoing resorption. Resorption was accompanied by haemorrhage, spiral artery dilation, hypocellularity of the decidua basalis, apoptosis of placental cells, a decline in uterine mature natural killer cell numbers, increased indoleamine 2,3-dioxygenase mRNA levels and reduced IL-15 mRNA levels. Given the role of IFN-gammaR(-/-) in non-infectious abortive processes, IFN-gammaR(-/-) mice were used to investigate its local role in T. gondii-induced foetal resorption. IFN-gammaR(-/-) mice showed 50% less foetal resorption than their wild-type counterparts, and spiral artery dilation and placental cell apoptosis were both abolished. These results strongly suggest that, at least in mice, T. gondii-induced abortion in early gestation is not due to a direct action of the parasite at the maternofoetal interface but rather to massive IFN-gamma release.

Cellular and molecular physiopathology of congenital toxoplasmosis: the dual role of IFN-gamma.

Toxoplasma gondii is one of the few pathogens that can cross the placenta. Frequency and severity of transmission vary with gestational age. While the control of acquired toxoplasmosis is already well explored, the control of materno-foetal transmission of the parasite remains almost unknown. This is partly due to the lack of an animal model to study this process. This review summarises the studies which have been undertaken and shows that the mouse is a valuable model despite obvious differences to the human case. The paramount role of the cellular immune response has been shown by several experiments. However, IFN-gamma has a dual role in this process. While its beneficial effects in the control of toxoplasmosis are well known, it also seems to have transmission-enhancing effects and can also directly harm the developing foetus. The ultimate goal of these studies is to develop a vaccine which protects both mother and foetus. Therefore, it is useful to study the mechanisms of natural resistance against transmission during a secondary infection. In this setting, the process is more complicated, involving both cellular and also humoral components of the immune system. In summary, even if the whole process is far from being elucidated, important insights have been gained so far which will help us to undertake rational vaccine research.