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PubMed1998

[Prevalence of latent toxoplasma infection in HIV infection patients].

BACKGROUND: To know the prevalence of Toxoplasma gondii latent infection in HIV-1 infected patients and to compare it with the prevalence in a group of parenteral drug users, non-infected by HIV. METHODS: We study 255 HIV-1 patients revised in our hospital in the last 6 years. The control group were 116 drug addicts non-infected by HIV followed in an educational program of deshabituation. We tested IgG anti-toxoplasma by enzymatic inmunoessay (MEIA). An IgG plasma value of 6UI/ML or more was an indicative of toxoplasma previous infection. We used Chi Square and Yatchts correction tests for the statistical analysis, settling down a significance point of 95%. RESULTS: We founded 36.7% positive IgG anti-toxoplasma in the group on HIV-1 infected patients, non drugs addicts, against 30.9% in the group of HIV-1 drug addicts patients. (OR 0.77; 0.35 < OR < 1.66). The control group showed a Toxoplasma seroprevalence of 26.7%, without statistically significant against the drug addicts HIV group (OR = 1.55; 0.93 < OREGON < 2.59). CONCLUSIONS: The seroprevalence of Toxoplasma gondii latent infection in our study was similar to the european results. We didn't found a higher prevalence in HIV-1 patients than in patients non infected by HIV-1.

Adult↗

PubMed2002

Antibiotics versus control for toxoplasma retinochoroiditis.

BACKGROUND: Acute toxoplasma retinochoroiditis causes transient symptoms of ocular discomfort and may lead to permanent visual loss. Antibiotic treatment primarily aims to reduce the risk of permanent visual loss, recurrent retinochoroiditis, and the severity and duration of acute symptoms. There is uncertainty about the effectiveness of antibiotic treatment. OBJECTIVES: The objective of this review was to compare the effects of antibiotics versus placebo or no treatment for toxoplasma retinochoroiditis. SEARCH STRATEGY: We searched the Cochrane Controlled Trials Register - CENTRAL/CCTR, which contains the Cochrane Eyes and Vision Group Specialised Register (Cochrane Library Issue 2, 2001), MEDLINE (1966 to August 2001), EMBASE (1980 to September 2001), Dissertation Abstracts (1861 to June 2001), LILACS (1982 to 1998), Pascal (1984 to March 2000), proceedings of the Association for Research in Vision and Ophthalmology (1980 to 2001), international symposia on uveitis, and reference lists of review articles. Pharmaceutical companies were contacted for unpublished trials. SELECTION CRITERIA: We included randomised controlled trials that compared any systemic antibiotic treatment against placebo or no treatment. Trials that included immunocompromised patients were excluded. DATA COLLECTION AND ANALYSIS: The primary outcomes for this review were visual acuity at least three months after treatment and risk of recurrent retinochoroiditis. Secondary outcomes were improvement in symptoms and signs of intraocular inflammation, size of lesion and adverse events. Effect measures were pooled using a random effects model. MAIN RESULTS: Three trials, which randomised a total of 173 participants, met the inclusion criteria. All trials were methodologically poor. None reported the effect of treatment on visual acuity. Two studies reported results for recurrent retinochoroiditis: one (124 participants) found a significant reduction in participants with chronic recurrent disease who were treated for 14 months: relative risk 0.28 (95% confidence interval 0.10 to 0.78); the other (20 participants) found no evidence of an effect in participants with acute toxoplasma retinochoroiditis (relative risk 1.00, 95% confidence interval 0.07 to 13.87). Two studies reported an improvement in intraocular inflammation in treated compared with untreated participants and one study reported no difference. Two studies found an increased risk of adverse events in treated participants. REVIEWER'S CONCLUSIONS: There is a lack of evidence to support routine antibiotic treatment for acute toxoplasma retinochoroiditis. There is weak evidence to suggest that long-term treatment of patients with chronic recurrent toxoplasma retinochoroiditis may reduce recurrence. Placebo controlled trials of patients with acute and chronic toxoplasma retinochoroiditis affecting any part of the retina are required to determine the effectiveness of antibiotic treatment.

Anti-Bacterial Agents↗

PubMedDate not supplied

The probability of acquiring primary Toxoplasma infection in HIV-infected patients: results of an 8-year retrospective study.

There is much hope that HIV-infected patients and AIDS patients can reckon with a prolonged survival in future. The increased survival of AIDS patients with positive Toxoplasma serology is not necessarily associated with an increased risk of developing Toxoplasma encephalitis. For HIV-infected patients with negative Toxoplasma serology, the probability of acquiring a primary Toxoplasma infection in highly endemic areas such as Germany had not been studied to date. One hundred eighty-three HIV-infected patients were followed up between 1987 and 1995 in a retrospective study. Within the cohort, 95% of the patients were male and 83% haemophiliacs. The initial (1987) and final (1995) prevalence rate of Toxoplasma antibodies was 33.3% and 36.6%, respectively. The annual rise of the primary infection rate was calculated as 0.41%. The dye test was used for the detection of Toxoplasma-specific antibodies. This assay proved to be reliable and stable during long-term observation. The rate of primary toxoplasmosis found in this long-term study was not higher than that of pregnant women in Germany. Chemoprophylactic measurements for seronegative HIV-infected patients are therefore not recommended, but regular serological screening to detect seroconverters is.

AIDS-Related Opportunistic Infections↗

PubMed1986

Antibodies to immune response gene products inhibit the IgM and IgG antibody response but not the development of resistance to Toxoplasma gondii.

We have examined the effects of a monoclonal antibody directed against immune response gene products on the appearance of antibodies and development of resistance to Toxoplasma gondii. In vivo administration of a single dose of anti-I-Ak antibody to C3H/He (H-2k) and not BALB/c (H-2d) mice suppressed both the IgM and IgG response to two different strains of Toxoplasma. Administration of anti-I-Ak antibody to mice 5 days before and 10 days after infection resulted in complete inhibition of IgM and a more pronounced inhibition of IgG response to Toxoplasma. Under these experimental conditions, development of resistance against a subsequent challenge with a virulent strain of Toxoplasma was not affected. The microbicidal and tumoricidal activities of macrophages obtained from anti-I-Ak-treated, Toxoplasma-infected mice and mice infected with Toxoplasma alone were equivalent. Mice treated with anti-I-Ak antibody demonstrated a decreased proliferative response to lipopolysaccharide, a B-cell mitogen. Enumeration of B-cell numbers in anti-I-Ak-treated mice revealed a pronounced decrease in B-cell counts.

Animals↗

PubMed2004

Toxoplasma gondii infection in animal-friendly pig production systems.

PURPOSE: Consumption of undercooked pork meat products has been considered a major risk factor for contracting toxoplasmosis in humans. Indoor farming and improved hygiene have drastically reduced Toxoplasma infections in pigs over the past decades. Whether introduction of animal-friendly production systems will lead to a reemergence of Toxoplasma infections in pigs is not yet known. Investigating this possibility was the purpose of this study. METHODS: Blood was obtained from pigs raised for slaughter and tested for Toxoplasma antibodies by using latex agglutination and indirect immunofluorescence testing, with confirmation by immunoblotting. RESULTS: None of the slaughter pigs (n = 621) from conventional farms (n = 30) were positive, whereas 38 (2.9%) of 1295 animals from animal-friendly systems tested positive (n = 33 farms; 13 [39%] farms positive). CONCLUSIONS: The following conclusions may be derived from this study: Conventionally (indoors) raised pigs are free from Toxoplasma infection, and (2) animal-friendly production systems may lead to a reemergence of Toxoplasma infections, although many of these farms remain Toxoplasma free. Slaughterhouse monitoring of pigs from animal-friendly production systems combined with on-farm prevention strategies should be applied to ensure safety for consumers of the meat products obtained from these animals.

Animal Husbandry↗

PubMed1992

Incidence of primary toxoplasma infections during pregnancy in southern Finland: a prospective cohort study.

Congenital toxoplasmosis may develop after maternal primary infection during pregnancy. Since toxoplasmosis in adults is usually asymptomatic, the only way to find the pregnancies at risk of acute toxoplasmosis (i.e. seronegative mothers) is to perform serological screening of all pregnant women. We studied toxoplasma-specific antibodies in 16,733 pregnant women in the first, second, and third trimesters over an 18-month period in the Helsinki area, with a population of 820,700. The participation rate in our study was 90.2% of all pregnancies in the area. The overall prevalence of toxoplasma seropositivity was 20.3%. The incidence of primary infection was 2.4/1000 pregnancies at risk. Our data on incidence suggest an annual occurrence of 131 cases of primary toxoplasma infections during pregnancy in Finland. Primary toxoplasma infection appears to be a significant risk to the fetus even in countries where the prevalence of toxoplasma seropositivity is low. The feasibility of mass screening for toxoplasma infections during pregnancy should be considered in order to reduce the morbidity and mortality due to congenital toxoplasmosis.

Adolescent↗

PubMed2005

[Toxoplasma encephalitis in a patient receiving cyclosporine monotherapy for Behçet disease].

We report a 44-year-old woman with toxoplasma encephalitis that occurred during cyclosporine monotherapy for Behçet disease. She had been treated with cyclosporine for 8 years. She experienced headache and, nausea, and then consciousness disturbance developed. Brain MRI showed high-signal intensity lesions on T1-weighted MRI with Gd-enhancement in the left temporoparietal lobe, right thalamus and right frontal and temporal lobes. The pathological examination of the biopsied brain specimens suggested toxoplasma encephalitis. She improved rapidly after the administration of antibiotics for toxoplasma gondii. Anti-toxoplasma specific protein antibodies were positive in the serum and CSF, supporting a diagnosis of acute toxoplasmosis. Toxoplasma encephalitis due to cyclosporine mono-therapy has not been reported yet. The measurement of anti-toxoplasma specific protein antibodies may be useful for the early, accurate diagnosis of toxoplasmosis.

Adult↗

PubMed1991

[Endogenous posterior uveitis and toxoplasma infection: a case-control study].

The present study was first carried out to evaluate the effects of toxoplasma infections on endogenous posterior uveitis in Tian in city. In this report, 118 cases of endogenous posterior uveitis and 236 clinical and health controls were studied by 1:2 pair match case-control method. The clinical controls were OPD patients without uveitis and the health controls were normal persons. The prevalence rate of toxoplasma infection in three groups were 31.4%, 11.9% and 9.3% respectively. The differences of three groups was higher significant. The odds ratio (OR) of toxoplasma infection in posterior uveitis was 3.72 (2.17-6.39). The difference of the two controlled groups was not significant. The odds ratio of toxoplasma infection in central exudative retinochoroiditis and panuveitis were 4.78 and 3.33. The toxoplasma infection was not significantly related to the optic retinitis. The results suggest that toxoplasma infection as a suspect agent of endogenous posterior uveitis.

Case-Control Studies↗

PubMed1983

Toxoplasma gondii--an environmental contaminant.

Toxoplasma gondii, the causal agent of toxoplasmosis, is a ubiquitous protozoan parasite which has the potential to infect man and all warm-blooded animals. It has as its definitive host the cat. Infections acquired by the human adult are generally subclinical. However, if acquired for the first time during pregnancy, the parasite can invade the developing foetus. Under these circumstances infection can result in abortion, stillbirth or production of live-born offspring with severe multiple organ involvement. Alternatively, offspring can be symptomless at birth but may manifest neurological and ocular sequelae of toxoplasmosis in later life. The degree of clinical involvement is thought to be dependent upon the time of acquisition of infection by the pregnant female. Recent investigations have been concerned with behavioural aspects of predator-prey relationships between cats and rodents. Since these aspects affect the spread of toxoplasmosis in the environment, they have strong epidemiological and ecological implications. Toxoplasma infection in the environment, they have strong epidemiological and ecological implications. Toxoplasma infection in mice is associated with subtle alterations in exploratory behaviour which are almost certainly maladaptive, rendering infected mice more susceptible to predation by cats. Consequently the behavioural abnormalities in mice associated with Toxoplasma infection would be of major importance for the continuation of the life-cycle of the parasite. Ingestion of Toxoplasma-infected mice leads to oocyst production in cats and this opens up the well-known pathway whereby Toxoplasma infection reaches the human species.

Animals↗

PubMed1980

Influence of chronic Toxoplasma infection on ethylnitrosourea-induced central nervous system tumors in rats.

Because prior work with mice had revealed remarkable inhibition of central nervous system (CNS) tumor by chronic Toxoplasma infection, the effect of immunomodulation produced by this obligate intracellular parasite was studied in rats which developed CNS tumors following transplacental exposure to the chemical carcinogen ethylnitrosourea. Groups of Fischer 344 rats which had been exposed to ethylnitrosourea were either uninfected or infected at 1 month of age with a virulent strain of Toxoplasma gondii. Rats were sacrificed when morbid symptoms from tumor growth developed, and neural tissue was prepared for light microscopy. Chronic Toxoplasma infection had no effect on the survival of rats or on the amount, location, or histological type of CNS tumor which developed. Although serum antibody to Toxoplasma was present in all infected rats for the duration of the experiment, there was no histological evidence in the brain of a cellular response to infection or to the presence of tumor. When these results are compared to prior experiments of CNS tumor in mice, they suggest that mechanisms of protection against Toxoplasma infection differ in mice and rats and that an inflammatory component produced by the Toxoplasma organism in the brain is a necessary prerequisite for tumor inhibition.

Animals↗

PubMed1993

Seroprevalence of Toxoplasma and cytomegalovirus in complicated pregnancies.

Anti-Toxoplasma and anti-cytomegalovirus (CMV) antibodies were sought in 200 pregnant women (100 with complicated pregnancies and 100 matched controls without any hazards) by ELISA test. Sixty-five per cent of the women with complicated pregnancies had Toxoplasma antibodies, while 51% had CMV antibodies. Toxoplasma seroprevalence alone was higher in women with intrauterine foetal death (IUFD) (80%). CMV seroprevalence alone was higher in women with premature labour (44.4%) and women with stillbirth (40%). Seroprevalence of both Toxoplasma and CMV was clearly higher in women with abortion (55.7%). Seroprevalence of Toxoplasma and CMV in the control group was 6% and 30%, respectively. These data confirm that Toxoplasma and CMV are important causes of complicated pregnancy.

Adult↗

PubMed1999

Transport and trafficking: Toxoplasma as a model for Plasmodium.

Like Plasmodium, the protozoan parasite Toxoplasma gondii is a member of the phylum Apicomplexa, and an obligate intracellular pathogen. Unlike Plasmodium, however, Toxoplasma is highly amenable to experimental manipulation in the laboratory. The development of molecular transformation protocols for T. gondii has provided both scientific precedent and practical selectable markers for Plasmodium. Beyond the feasibility of molecular biological experimentation now possible in both systems, the high frequency of stable transformation in Toxoplasma allows this parasite to be used for molecular genetic analysis. The ability to control homologous vs. non-homologous recombination in T. gondii permits gene knockouts/allelic replacements at previously cloned loci, and saturation insertional mutagenesis of the entire parasite genome (and cloning of the tagged loci). T. gondii also exhibits unusual ultrastructural clarity, facilitating cell biological analysis. The accessibility of Toxoplasma as an experimental system allows this parasite to be used as a surrogate for asking many questions that cannot easily be addressed in Plasmodium itself. T. gondii also serves as a model system for genetic exploration of parasite biology and host-parasite interactions. Success stories include: biochemical analysis of antifolate resistance mechanisms; pharmacological studies on the mechanisms of macrolide activity; genetic identification of nucleobase/nucleoside transporters and metabolic pathways; and cell biological characterization of the apicomplexan plastid. As with any model system, not all questions of interest to malariologists can be addressed in Toxoplasma; differentiating between sensible and foolish questions requires familiarity with the biological similarities and differences of these systems.

Animals↗

PubMed1980

Concurrent infections of Trichinella spiralis and Toxoplasma gondii in mice.

Concurrent infections with two parasites: a nematode, Trichinella spiralis, and a protozoon. Toxoplasma gondii, were investigated. Antibody production (total immunoglobulin and IgM) was similar in double and single infections. However, the number of Toxoplasma cysts in the brains of mice infected with Trichinella and challenged 1-6 weeks later with Toxoplasma was higher than in mice infected with Toxoplasma alone, while mice infected with Toxoplasma and challenged 4-14 days later with Trichinella had lower worm burdens in the intestine than animals infected with Trichinella alone. Greater loss in body weight was observed in mice infected with both parasites than in those infected with either parasite alone.

Animals↗

PubMed1981

Infection of murine peritoneal macrophages with Toxoplasma gondii exposed to ultraviolet light.

Exposure of Toxoplasma trophozoites to ultraviolet light (UV; 2,539 A) remarkably inhibited intracellular multiplication of the toxoplasmas within cultured mouse peritoneal macrophages. These toxoplasmas possessed the ability to induce normal parasitophorous vacuoles (PV) and underwent gradual degeneration in the PV without participation of host-cell lysosomes. Apparently, the basic conformation of the PV, i.e., the association of mitochondria, rough endoplasmic reticulum, and microtubules of the host cell and the presence of microvillous infoldings, was maintained as seen under the electron microscope even after the toxoplasmas had died within the PV. Even PV, in which debris of the toxoplasmas could be observed, did not show the sign of fusion with ferritin-labeled secondary lysosomes.

Animals↗

PubMed1985

Enzyme-linked immunosorbent assay for detection of soluble Toxoplasma gondii antigen in acute-phase toxoplasmosis.

Sixty-two sera from 51 patients with lymphadenopathy presumed to be due to acute-phase toxoplasmosis were tested for specific IgM class antibodies by both the immunofluorescence antibody to Toxoplasma gondii in sera were first dissociated in 3 M NaSCN. Antigen attached to the solid phase was detected with enzyme-coupled IgG antibody to Toxoplasma antibody to Toxoplasma gondii in sera were first dissociated in 3 M NaSCN. Antigen attached to the solid phase was detected with enzyme-coupled IgG antibody to Toxoplasma gondii. Neither hepatitis B surface antigen nor antigen of Mycoplasma pneumoniae, rubella, cytomegalovirus or herpes simplex virus interfered with this ELISA. Soluble antigen was detected in 13 (30%) of 42 IgM-positive acute-phase toxoplasmosis patients and in only one of 20 sera cleared of IgM. None of an additional 44 IgM-negative patients with low IgG titres had a positive result in the antigen ELISA. Follow-up studies in four acute-phase toxoplasmosis patients showed that the soluble antigen cleared in all cases before the specific IgM antibodies. Simultaneous detection of IgM antibodies to Toxoplasma gondii and soluble antigen would thus seem to indicate an early stage of the infection.

Antibodies↗

PubMed2001

Multicenter evaluation of strategies for serodiagnosis of primary infection with Toxoplasma gondii.

The diagnostic performance of single-serum assays for toxoplasma-specific immunoglobulin (Ig)M. IgA. IgG, and IgE antibodies and of different combinations of such antibody assays in 20 European reference centers was assessed. A panel of 276 sera, of which 73 came from patients who seroconverted within 3 months (acute infection), 49 from patients who had seroconverted 3-12 months earlier (convalescence), and 154 from subjects who had two IgG-positive samples obtained 12 months apart (past infection), was tested with 20 toxoplasma-antibody assays and 195 combinations. In general, every assay with high diagnostic sensitivity showed low diagnostic specificity, i.e. no assay performed alone could reliably distinguish acute from past infection. Furthermore, no single assay (or combination) could separate convalescence from the other stages of toxoplasma infection. However, excellent diagnostic performances were reached by sequential use of highly sensitive IgM assays and methods examining IgG avidity or stage specificity. IgA or IgM assays were less suitable for confirmation of toxoplasma-IgM positivity. This study documents the strength of test combinations in assessing the stage of toxoplasma infection.

Acute Disease↗

PubMed1997

T cell receptor specificities of Toxoplasma gondii-reactive mouse CD4+ T lymphocytes and Th1 clones.

The Toxoplasma gondii-directed CD4+ T cell response in chronically infected mice was studied with respect to both T cell receptor diversity and antigen specificities. T cell receptor chains V beta 4, 6, 8, 10, and 14 were predominantly found on toxoplasma-reactive CD4+ splenocytes. This repertoire was also detected among T. gondii-specific CD4+ T cell clones. Analysis of clonotypic cytokine profiles revealed typical Th1 clones secreting interleukin-2, interferon-gamma and tumour necrosis factor activity and Th2 clones producing interleukin-4 and interleukin-10. Five distinct toxoplasma antigens (p26, p40, p55, p58 and p60) were detected in electrophoretically separated toxoplasma lysate by five individual Th1 clones. Parallel testing of CD4+ T lymphocytes from infected mice confirmed that these specificities constitute the peak immunogenic fractions of toxoplasma lysate. The expression patterns of two clonotypic, T cell-stimulatory parasite antigens were studied in detail. While p55 was expressed by mouse-virulent and avirulent T. gondii isolates and in both the tachyzoite and bradyzoite stages, p58 was detected only in virulent strains from intraspecies subgroup I. Thus, we describe the heterogeneity of toxoplasmic immunodominant T cell antigens including a 58-kDa group I-restricted molecule which may provide a marker for virulent isolates.

Animals↗

PubMed2001

Some factors influencing transmission of toxoplasma in pregnant rats fed cysts.

An overall 44% transplacental transmission rate was observed in 221 rats fed cysts of 12 Toxoplasma strains at 15 days of pregnancy, with a range of 0-90% transmission. Considerable variability in the transmission rate was seen among different groups of rats that received similar Toxoplasma inocula; this is attributed to genetically based susceptibility to Toxoplasma among individuals of the outbred Wistar strain of rats. Transplacental transmission was more frequent in Long Evans than in Wistar rats. Significant differences in the rate of transmission were not found between rats that were fed similar Toxoplasma inocula 6-8 days or 15 days after conception. The frequency of transmission was not affected by the strain or dose of Toxoplasma used.

Animals↗