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[Toxoplasmosis as anthropo-zoonosis and its immunodiagnostics in Lithuania].

Anti-Toxoplasma IgG antibodies were found in 43.2% of examined mothers, infants and children below 14 years of age, whereas IgM antibodies were found in 6.2% of the examined persons only. Diagnoses of acquired and congenital toxoplasmosis were based on the results of clinical examination and immunological confirmation. In infants, anti-Toxoplasma IgG antibodies are not indicative of Toxoplasma invasion, since they frequently come from mother and then disappear by the end of the first year of life, whereas finding of specific immunoglobulins M is the evidence of congenital toxoplasmosis.

Adolescent↗

[Toxoplasmosis and pregnancy. Multicenter study of 16,362 pregnant women in Barcelona].

BACKGROUND AND OBJECTIVE: The aim of this study was to know: 1) the prevalence of antibodies against toxoplasma in pregnant women, 2) the incidence of primary infection during pregnancy and 3) the prevalence of congenital toxoplasmosis. SUBJECTS AND METHOD: Seroprevalence was prospectively analyzed in 16,362 pregnant women visited in 8 hospitals and 2 day care centers in Barcelona during 1999. Each participant laboratory included their own assays to detect toxoplasma-specific immunoglobulins IgM, IgA, IgG and IgG avidity antibodies. In case of positive specific IgM, a second serum sample was requested, which was processed in parallel with the first one. Three infection stages were defined: acute, possible and past (latent). Congenital infection was determined prenatally by polymerase chain reaction (PCR) in amniotic fluid or postnatally by serology in the newborn. RESULTS: Seroprevalence was 28.6%. The incidence of primary infection during pregnancy was 1.02/1,000 susceptible pregnant women. Nine women out of 12 with an acute toxoplasma infection became seroconverted during their pregnancies and five of them had infants with congenital toxoplasmosis (vertical transmission: 41.6%). All four children born alive had no symptoms during their follow-up. CONCLUSIONS: In this study, the prevalence of toxoplasmosis was low. Acute toxoplasmosis was detected mainly by seroconversion during pregnancy. The frequency of maternal-fetal transmission was near half of cases.

Female↗

[Human toxoplasmosis].

Toxoplasmosis infection is transmitted from cat faeces or insufficiently heated meat from e.g. pigs, sheep and goats. If pregnant women are infected with Toxoplasma gondii, there is a risk of infection of the foetus with the possibility of development of congenital toxoplasmosis and, in patients with AIDS, a latent infection may be activated with subsequent fatal encephalitis. Human infections with T. gondii are common but are frequently asymptomatic. The prevalence of T. gondii infection in the Danish population is not known exactly but preliminary investigations among pregnant women have revealed a prevalence of approximately 33% and the annual incidence is calculated to 0.5%. Legal abortion should be offered to pregnant women in whom toxoplasmosis is diagnosed on account of the risk of foetal damage. If legal abortion is not accepted or is not possible, treatment with spiramycin should be instituted. In immunosuppressed individuals with evidence of activation of latent T. gondii infection and children with congenital toxoplasmosis, treatment with combined pyrimethamine and sulphadiazine should be administered. Information about the routes of infection is important, particularly for sero-negative pregnant women as the routes of infection are limited so that it is reasonably easy to avoid infection.

Denmark↗

Immunoglobulin G avidity in diagnosis of toxoplasmic lymphadenopathy and ocular toxoplasmosis.

Traditional serological techniques have some limitations in evaluating the duration of Toxoplasma gondii infection in pregnant women, patients with lymphadenopathy, and older children suspected of having congenital toxoplasmosis. In these three groups of patients, two variants of T. gondii immunoglobulin G (IgG) avidity tests were used: an EIA Kit (Labsystems) and a noncommercial enzyme-linked immunosorbent assay specially elaborated in the laboratory. The avidity of specific IgG in sera from 23 patients with a known recently acquired infection (mainly pregnant women) was low (less than 30%), whereas that in sera from 19 patients with toxoplasmic lymphadenopathy of 3 weeks to 6 months in duration (mean, 8.3 weeks) covered a large range (between 0.2 and 57.8%; mean, 25. 7%); high avidity results were observed for 10 of 19 patients (52. 6%). The large range of IgG avidity in patients with toxoplasmic lymphadenopathy suggests various durations of infection in these patients, with a tendency for a chronic phase of toxoplasmosis. According to the avidity marker, five patients with lymphadenopathy for less than 3 months did not have a recent Toxoplasma infection. In 6 of 19 patients with lymphadenopathy (31.6%), low IgG avidity values persisted until 5 months after the first serological examination. In all four patients with a documented chronic course of Toxoplasma infection (6 months to 8 years after the first positive serology), high IgG avidity values were observed. Among sera from 10 children and young immunocompetent adults suspected of having ocular reactivation of congenital toxoplasmosis, all had high IgG avidity values (over 40%), suggesting congenitally acquired ocular infection rather than noncongenital infection. In conclusion, the avidity of IgG is a valuable marker of recent toxoplasmosis in pregnant women, suggests the duration of invasion in patients with lymphadenopathy, and may be helpful for differentiation between reactivation of congenital infection and recently acquired ocular toxoplasmosis in immunocompetent patients. A low IgG avidity does not always identify a recent case of toxoplasmosis, but a high IgG avidity can exclude primary infections of less than 5 months' duration.

Adult↗

IgA antibodies against P30 as markers of congenital and acute toxoplasmosis.

Specific IgA antibodies against P30, a major surface protein of Toxoplasma gondii were sought in 198 serum samples (from 133 patients) by means of a double-sandwich enzyme-linked immunosorbent assay. These antibodies were detected in all cases of acute toxoplasmosis but in no cases of chronic toxoplasmosis nor in seronegative patients. They were not detected in samples from patients with "natural IgM antibodies" or in those containing rheumatoid factor or antinuclear antibodies. Among 26 infants whose mothers were infected during pregnancy, anti-P30 IgA antibodies were exclusively detected in the samples from the 8 infected infants, although anti-P30 IgM antibodies were detected in only 3 of the infected infants. No uninfected infant had IgA, though 5 had IgM at birth. Thus, the detection of IgA anti-P30 antibodies seems a better means than the detection of IgM antibodies of identifying infected infants, which is very important for treatment. In addition, the very early detection of IgA antibodies may be important for the diagnosis of acute toxoplasmosis, especially during pregnancy and perhaps also in patients infected by human immunodeficiency virus.

Acute Disease↗

Toxoplasmosis transmitted to a newborn from the mother infected 20 years earlier.

PURPOSE: To present a case of congenital toxoplasmosis in a newborn whose mother had a 20-year history of a chorioretinal macular scar and positive serology for toxoplasmosis. DESIGN/METHODS: Case report. SETTING/RESULTS: A 38-year-old woman who had been treated for ocular toxoplasmosis 20 years earlier delivered a newborn who presented with a focal necrotizing retinochoroiditis characteristic of toxoplasmosis, as well as positive immunoglobulin (Ig) G and M serology for toxoplasmosis. The workup was negative for other entities. CONCLUSION: This case suggests that women with old retinal scars due to toxoplasmosis and long-standing IgG antibodies to toxoplasmosis are also at risk of transmitting this disease to the fetus.

Adult↗

Fetal toxoplasmosis: outcome of pregnancy and infant follow-up after in utero treatment.

Eight-nine cases of fetal Toxoplasma infection are reported in women treated with spiramycin during pregnancy. Thirty-four pregnancy terminations were performed (2.7% of the total number of acquired Toxoplasma infections during pregnancy). Fifty-two pregnancies were allowed to proceed (43 being additionally treated with pyrimethamine and sulfonamides), leading to the birth of 54 live infants. After a mean follow-up period of 19 months, 41 infants had evidence of subclinical Toxoplasma infection, 12 had a benign form, and one had severe congenital toxoplasmosis (this infant did not receive the additional treatment during pregnancy). Efficacy of the additional treatment with pyrimethamine and sulfonamides was demonstrated by a significant reduction of severe congenital toxoplasmosis and the relative decrease of the ratio of benign to subclinical forms. We recommended that spiramycin treatment be started as soon as possible once the diagnosis of maternal Toxoplasma infection during pregnancy is proved or strongly suspected, because a prolonged time interval between onset of infection and start of treatment seems to be associated with the presence of severe fetal lesions at the time of prenatal diagnosis.

Female↗

[Toxoplasmosis in pregnancy: prevention, prenatal diagnosis and treatment].

Maternal infection with Toxoplasma gondii acquired during pregnancy occurs in more than 500 women per year in Switzerland. Systematic screening at the beginning of pregnancy allows the introduction of health education programs. The screening during pregnancy is performed to diagnose primary maternal infections and to propose prenatal diagnosis and treatment. The administration of specific antibiotherapy during pregnancy (spiramycine or the association of pyrimethamine and sulfonamides) significantly reduces the risk of fetal infection. Prenatal diagnosis of congenital toxoplasmosis is possible and reliable. It avoids unnecessary termination of pregnancy when the fetus is not infected and specific therapy in case of infection (association of pyrimethamine and sulfonamides). Prenatal treatment may be proposed without prenatal diagnosis as of the 16th week of gestation. In any case, prenatal treatment seems to reduce the incidence of severe congenital toxoplasmosis.

Coccidiostats↗

An enzyme-linked immuno-filtration assay used to compare infant and maternal antibody profiles in toxoplasmosis.

Enzyme-linked immuno-filtration assay is carried out on a micropore membrane. This doubly analytical technique permits simultaneous study of antibody specificity by immunoprecipitation and characterisation of antibody isotypes by immuno-filtration with enzyme-labelled antibodies. Recognition of the same T. gondii antigenic constituent by IgG, IgA, IgM or IgE antibodies produces couplets (IgG-IgM; IgG-IgA) or triplets (IgG-IgM-IgA; IgG-IgM-IgE) which identify the functional fractions of the toxoplasmosis antigen. In acquired toxoplasmosis, the persistence of IgM antibody long after infestation puts in question the implication of recent infestation normally linked to detection of this isotype. For sera of comparable titres, comparison of immunological profiles by the method described demonstrates disparities in the composition of the specific antibody content as expressed in international units. Use of the same method to detect IgM antibodies or distinguish between transmitted maternal IgG and IgG antibodies synthesised by the foetus or neonate makes a diagnosis of congenital toxoplasmosis possible in 85% of cases during the first few days of life. With the method described the diagnosis may be made on average 5 months earlier than with classical techniques. In the course of surveillance for latent congenital toxoplasmosis, the appearance of IgM or IgE antibodies raises the possibility of complications (hydrocephalus, chorioretinitis). After cessation of treatment, a rise in IgG antibodies indicating persistence of infection is detected earlier by the present than by classical methods.

Antibodies↗

Gestational and neonatal toxoplasmosis: regional seroprevalence in the United Arab Emirates.

Paired maternal/cord blood samples were tested for anti-Toxoplasma IgG or IgM antibodies using Biomerieux Micro-EIA2 IgG and IgM test kits. Of the 1503 women tested at the time of delivery, 344 (22.9%) were IgG seropositive. Three hundred and one maternal sera, including 265 that were IgG positive, were tested for IgM antibodies: 47 were found positive, indicating a gestational toxoplasmosis incidence of 31 per 1000 pregnancies over one year. All but one of the IgM positive maternal sera had tested IgG positive. Cord blood IgG seropositivity was similar to the maternal rate but 18 of the 301 babies had significant levels of anti-Toxoplasma IgM antibodies. As these 18 babies were all born to mothers also positive for IgM antibodies, the calculated rate of transplacental transmission was 38.3% with the estimated prevalence of congenital toxoplasmosis of 12 per 1000 live births. There was no statistically significant positive correlation between maternal seroprevalence and such well-known risk factors as consumption of raw meat and milk, or proximity of cats and other animals. One baby was born with the classical stigmata of congenital toxoplasmosis.

Adolescent↗

Does human toxoplasmosis involve an imbalance in T1/T2 cytokines?

The T1 (interferon-gamma, interleukin-12, interleukin-2) and T2 (interleukin-4, interleukin-10, interleukin-6) cytokine groups constitute two polar responses of the immune system. The T1 group is a predominantly cellular response, while the T2 group response is mainly humoral. The hypothesis forwarded here links these subgroups of induced cytokines to the various clinical forms of human toxoplasmosis. Ocular toxoplasmosis in immunocompetent patients could be attributed to a T1 hyper-response, whereas congenital toxoplasmosis, toxoplasmic encephalitis (in immunodeficient patients) and active chronic toxoplasmosis (with persistent lymphadenophathy) would be characterized by a predominantly T2 response. Confirmation that this kind of immunological imbalance effectively underlies the various clinical forms of toxoplasmosis would open the way for a new range of treatments based on immunomodulation.

Animals↗

Toxoplasmosis: comparative species susceptibility and host immune response.

The protozoan parasite Toxoplasma gondii is capable of infecting all warm blooded animals; however, the consequences of infection are very variable between different species of animal. Marsupials and New World monkeys, which have evolved largely separately from the cat, the definitive host of the parasite, are among the most vulnerable species where infection with T. gondii can prove fatal. In more resistant species such as humans and sheep, infection is generally unapparent, provoking only mild symptoms; thereafter the host remains infected for life. However, when the immune system is compromised, such as in the immunologically immature fetus, infection with the parasite can have very serious consequences. Much of the work examining host immune responses has been done using experimentally infected mice. While there are many advantages in using this experimental model, care should be taken in extrapolating results from mice to other species. Mice are extremely vulnerable to the consequences of infection with T. gondii., and their use to further our understanding of congenital toxoplasmosis may not be ideal, as fetal infection can occur in successive pregnancies. This is not the case in rats or sheep; they are more resistant to the disease and therefore may provide a more relevant model for human congenital toxoplasmosis. Studies of host immune responses have emphasised the importance of the cytokine interferon gamma (IFN gamma) in resistance to T. gondii. The efficiency of induction of this cytokine may be critical for determining the outcome of the host-parasite relationship.

Animals↗