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At least 127 records · Page 7Linked to original sources

PubMed1989

Antigen presentation by Toxoplasma gondii-infected cells to CD4+ proliferative T cells and CD8+ cytotoxic cells.

Cytotoxic cells specific for Toxoplasma gondii-infected cells were detected in the peripheral blood leukocytes from a patient with acute toxoplasmosis. The cytotoxicity was mediated by CD5+, CD4-, CD8+ cells. The cytotoxic T cells lysed Toxoplasma-infected target cells with HLA class I restriction. Two types of T cell clones were established from peripheral blood leukocytes of a patient with chronic toxoplasmosis; one was a CD5+, CD4-, CD8+ cytotoxic cell specific for Toxoplasma-infected cells, and the other was a CD5+, CD4+, CD8- proliferative cell that responded to Toxoplasma antigen. Toxoplasma-infected cell-specific cytotoxic cloned T cells recognize the infected target cells in the context of the HLA class I molecules, and the CD8 molecule was involved in the cytotoxicity. Toxoplasma antigen-specific proliferative cloned T cells were stimulated by Toxoplasma antigen-pulsed or Toxoplasma-infected cells in conjunction with HLA-DR molecule on the target cells. Thus, antigen presentation by Toxoplasma-infected cells for activation of both cytotoxic and proliferative T cells has been demonstrated.

Animals↗

PubMed1999

Feasibility of neonatal screening for toxoplasma infection in the absence of prenatal treatment. Danish Congenital Toxoplasmosis Study Group .

BACKGROUND: The best method for prevention and control of congenital toxoplasma infection is uncertain. Prenatal screening is done in Austria and France, but the effect of treatment during pregnancy is not well documented. The aim of our study was to find out the maternofetal transmission rate and outcome in infants born to mothers who were not treated during pregnancy. METHODS: We analysed 89873 eluates from phenylketonuria (PKU) cards from neonates and paired first-trimester serum samples from the mothers for specific IgG antibodies to Toxoplasma gondii. Children born to mothers who seroconverted during pregnancy were followed-up clinically and serologically to 12 months of age. In addition, 21144 PKU cards were analysed for toxoplasma-specific IgM antibodies during the last 12 months of the study. FINDINGS: In 24989 (27.8%) cases both the PKU eluate and the first-trimester samples were IgG positive, which indicates previous maternal infection. 139 of the 64884 seronegative women acquired toxoplasma infection during pregnancy and gave birth to 141 infants (two sets of twins). 27 of these children were diagnosed with congenital toxoplasma infection. The transmission rate was 19.4% (95% CI 13.2-27.0). Clinical signs and symptoms were found in four (15%) of the 27 children. The additional analysis for toxoplasma-specific IgM antibodies from the PKU card identified seven of nine children with congenital toxoplasma infection. The false-positive rate for the IgM test was 0.19 per 1000, and no false-negatives were found. INTERPRETATION: The risks of transmission of infection and of disease in the infant are low in an area with a low risk of toxoplasma infection. A neonatal screening programme based on detection of toxoplasma-specific IgM antibodies alone will identify between 70% and 80% of cases of congenital toxoplasmosis.

Adult↗

PubMed1996

Maternal and neonatal prevalence of toxoplasma and cytomegalovirus (CMV) antibodies and hepatitis-B antigens in an Egyptian rural area.

To determine the seroprevalence of maternal and neonatal toxoplasmosis and cytomegalovirus (CMV) antibodies and hepatitis-B (HB) antigenaemia in a rural Egyptian area, a prospective serological study was done on a randomly selected sample of pregnant women (n = 150) and their newborn infants (n = 150). Sera were collected from the mothers during the first antenatal visit, and at the time of delivery and cord blood specimens (paired samples) taken from their infants to be tested for toxoplasma-IgG and IgM antibodies, CMV-IgG and IgM antibodies surface antigen (HBsAg) and HBe antigen (HBeAg). Maternal infection was indicated in cases where specific IgM antibody was present or where an initial maternal specimen gave negative result for IgG antibody, but the second blood specimen gave positive result. Specific IgM antibody in a cord blood specimen indicated fetal infection. Out of the 150 pregnant women, 64 (43 percent) were toxoplasma immune at their first antenatal visit and their newborns were toxoplasma IgG positive. Toxoplasma specific IgM antibody was detected in only three mothers at the time of deliver. The rate of maternal infection in susceptible pregnancies was 4 percent and the maternal-fetal transmission rate was estimated to be 33 percent, as only one newborn infant had toxoplasma-IgM antibody at birth. This denoted a prevalence of congenital toxoplasma infection = < 1.0 percent to non-immune mothers. There were no clinical features of congenital infection in the infant with toxoplasma-IgM antibody, but he will require long-term follow-up. All the mothers infected during pregnancy had known risk factors for toxoplasma infection. One-hundred-and-forty-three (96 percent) of the pregnant women were CMV-IgG seropositive at their first antenatal visit. At the time of delivery 143 (96 percent) of the mothers and their newborn infants were CMV-IgG seropositive. None of the mothers or their infants was CMV-IgM seropositive. HBsAg was detected in 8 per cent of pregnant mothers (n = 12) and in two (17 percent) of their newborn infants. None of the mothers was HBeAg positive. In conclusion, the prevalence of toxoplasma infection during pregnancy and its transplacental transmission rate in a rural Egyptian area are high compared to other countries. A toxoplasmosis antenatal screening and public education programmes for pregnant mothers is justifiable in rural Egypt. However, it appears that an antenatal screening programme for CMV is, at present, not warranted.

Animals↗

PubMed2005

[The importance and validity of anti-Toxoplasma gondii IgG, IgM, IgA antibodies and IgG avidity tests in the diagnosis of Toxoplasmosis infection during pregnancy.].

Detection of specific IgG, IgM and IgA antibodies by enzyme immunoassay (EIA) tests are not always sufficient in the diagnosis of early and late Toxoplasma gondii infection during pregnancy. For this reason, the specific IgG avidity test should be used to detect primary toxoplasmosis infection. In this study, an investigation was made of the serological status of pregnant women who were suspected of having primary or late toxoplasmosis as well as the importance and relationship of specific anti-Toxoplasma gondii IgG, IgM and IgA antibodies and specific IgG avidity in their sera. TORCH panels were also used for these patients. A total of 52 pregnant women who were admitted in the Dokuz Eylül University Gynecology and Obstetrics Clinic were included in this study. The sera were sent to the serology and immunology laboratory for investigation of the anti-Toxoplasma gondii IgG, IgM and IgA antibodies by the EIA (Cobas Core, Roche, Germany and ETI-TOXOK-A, DiaSorin, Germany) technique. The anti- Toxoplasma gondii IgG avidity test was performed on IgG as well as IgM and/or IgA in positive sera with the EIA (Toxoplasma IgG Avidity EIA Well- RADIM, Italia) technique. The anti-Toxoplasma gondii IgG avidity test was not performed on sera from 21 pregnant women negative for anti-Toxoplasma gondii IgG, IgM and IgA antibodies. Borderline and high IgM levels showed a good correlation with the IgG avidity results. The ratio for the IgM and IgA positivity was 32.3% and both the IgM positivity and IgA negativity were 29%. In conclusion, anti- Toxoplasma gondii IgG avidity and anti-Toxoplasma gondii IgM antibody tests should be used together. However, positivity or high avidity of IgA was limited in the diagnosis of active toxoplasmosis infection of pregnant women.

English Abstract↗

PubMed1996

The prevalence of Toxoplasma antibody in patients with various ocular diseases in central Japan.

BACKGROUND: Ocular toxoplasmosis has been considered to be a largely asymptomatic infection because of the high seroprevalence of Toxoplasma antibodies and the low rate of clinical diagnosis. On the other hand, Toxoplasma infection has been reported to be associated with the other ocular disease. To investigate the association of Toxoplasma infection with the development of various ocular diseases, we studied Toxoplasma seroprevalence in patients with various ocular diseases. METHODS: We investigated Toxoplasma seroprevalence in 982 patients with various ocular diseases in central Japan. Then we compared the seroprevalence of anti-Toxoplasma antibodies. RESULTS: Of 982 patients with various ocular diseases, 122 (12.4%) had serological evidence of previous exposure to Toxoplasma gondii. There were no statistically significant differences among the patients with various ocular diseases. However, the seroprevalence in patients aged 40 to 99 years with macular degenerative lesions was significantly higher than that in patients without these lesions (P < 0.05, Yates' correction). CONCLUSION: This result suggests that Toxoplasma infection could play some role in the development of a type of macular degenerative lesion.

Adolescent↗

PubMed2005

Antigenaemia and antibody response to Toxoplasma gondii in human immunodeficiency virus-infected patients.

Toxoplasma encephalitis in immunocompromised patients results from reactivation of previously acquired (latent) infection. The aim of the study is to assess the antigenaemia and antibody response to Toxoplasma gondii in human immunodeficiency virus (HIV)-infected patients to determine the best marker for early diagnosis of toxoplasmosis in such patients. Indirect enzyme-linked immunosorbent assay (ELISA) for detection of IgG, IgM and IgA anti-toxoplasma antibodies and double-sandwich ELISA for toxoplasma antigen is carried out in serum samples collected from 100 HIV seropositive patients and 75 controls. Toxoplasma-specific IgG, IgM and IgA antibody response and antigenaemia were detected in 12%, 6%, 7% and 14% of HIV-infected patients, respectively. On retrospective analysis of 14 patients with antigenaemia only one had central nervous system (CNS) symptoms attributable to toxoplasma infection. In this patient, the CD4+ cell count was below 50/microL and none of the specific immunoglobulin isotype responses could be detected. The patient showed clinical improvement following specific chemotherapy for toxoplasmosis. In 25 HIV-negative and anti-toxoplasma IgG antibody-positive controls, IgM was detected in two (8%), IgA in five (20%) and antigenaemia in 10 (40%), while 50 HIV seronegative healthy controls were negative for both antigen and antibody responses. The study indicates that detection of toxoplasma antigen in addition to IgG antibody response may prove to be a useful indicator in the early diagnosis of reactivated toxoplasmosis in HIV/AIDS patients.

Acquired Immunodeficiency Syndrome↗

PubMed1972

The interaction between Toxoplasma gondii and mammalian cells. I. Mechanism of entry and intracellular fate of the parasite.

Macrophage, fibroblast, and HeLa cell cultures have been infected with Toxoplasma gondii, and observations have been made on parasite entry and fate. A special procedure was devised for studying the entry of toxoplasmas by electron microscopy. Toxoplasmas were centrifuged onto the cells in the cold; fixation 1-3 min after warming yielded specimens showing numerous examples of parasites in the process of entering cells. The mechanism of entry into macrophages, fibroblasts, and HeLa cells was in all cases by phagocytosis. Micropseudopods were extended by the cells to envelop the attached parasites in a typical phagocytic vacuole. Apparently the toxoplasmas stimulated this response of HeLa cells and fibroblasts, cell types not usually phagocytic. No instance was seen of penetration of toxoplasmas through the cell membrane, or of parasites located free in the cytoplasm. Essentially all of the toxoplasmas that entered HeLa cells divided with a generation time of 9 hr; the parasites formed large rosettes situated in vacuoles, eventually leading to host cell rupture. Macrophages took in larger numbers of toxoplasmas than did HeLa cells, but approximately half of the parasites inside of macrophages degenerated within a few hours. The surviving toxoplasmas in macrophages divided every 8 hr, forming rosettes and eventually rupturing the cells.

Animals↗

PubMed1975

Assessment in vitro of immunity against Toxoplasma gondii.

Studies have been made on humoral and cellular immune respones in mice immunized with an attenuated strain of Toxoplasma gondii. Heat-inactivated antitoxoplasma serum did not cause morphologic changes in the organisms, but did markedly influence their interactions with host cells. Toxoplasma exposed to antibody were no longer capable of entering fibroblasts or HeLa cells. They were readily engulfed by macrophages, but the antibody treatment strikingly altered the intracellular fate of the parasites leading to killing and digestion of the toxoplasmas in phagolysosomes. Addition of antitoxoplasma antibody immediately after infection of macrophages in vitro had no effect on intracellular multiplication of the organism. The division time of virulent toxoplasmas in mouse peritoneal macrophages in vitro was markedly prolonged in cells from immunized mice. During the first 2-3 mo after immunization, the macrophages harvested from the peritoneal cavity demonstrated this cellular immunity directly; thereafter exposure of the macrophages to immune lymphocytes and toxoplasma antigen, or to supernates from such an interaction was required for induction of the maximal capacity to inhibit growth of toxoplasmas. Induction of the alternation in macrophages by the lymphocyte product was detectable in 6 h and maximal at 18-24 h. Cultivation in vitro of macrophages from immunized animals for periods longer than 48 h rendered the cells nonresponsive to the immune lymphocyte-toxoplasma product. Macrophages from the peritoneal cavities of normal, nonimmunized mice were also incapable of developing the capacity to inhibit growth of toxoplasmas in response to this product. The nonresponsiveness of normal macrophages, or of macrophages cultured for several days in vitro was not changed by exposure of the cells to antitoxoplasma serum.

Animals↗

PubMed1995

Cross-reactivity of human Toxoplasma-specific T cells: implications for development of a potential immunotherapeutic or vaccine.

Previous reports from this laboratory have demonstrated that human CD4+ Toxoplasma-specific cytotoxic T cell (CTL) clones generated by stimulation of peripheral blood mononuclear cells with Toxoplasma RH strain antigens also recognized target cells expressing C strain antigens. To extend these observations, additional Toxoplasma isolates were studied. A simple system for assessment of cytotoxicity using T cell lines rather than cloned CTL was used. Stimulation of human peripheral blood mononuclear cells with Toxoplasma RH strain antigens elicited cytotoxic T cell lines specific for target cells expressing antigens derived from many other Toxoplasma strains. Cell lines produced by stimulation with antigens derived from the related, nonpathogenic coccidian Besnoitia jellesoni were also cytotoxic for target cells expressing Toxoplasma antigens. Proliferative responses to many Toxoplasma isolates and to the Toxoplasma p30 protein were also noted.

Animals↗

PubMed2006

Induction of dendritic cell migration upon Toxoplasma gondii infection potentiates parasite dissemination.

The processes leading to systemic dissemination of the obligate intracellular parasite Toxoplasma gondii remain unelucidated. In vitro studies on human and murine dendritic cells (DC) revealed that active invasion of DC by Toxoplasma induces a state of hypermotility in DC, enabling transmigration of infected DC across endothelial cell monolayers in the absence of chemotactic stimuli. Infected DC exhibited upregulation of maturation markers and co-stimulatory molecules. While modulation of cell adhesion molecules CD11/CD18 was similar for Toxoplasma-infected DC and lipopolysaccharide (LPS)-matured DC, Toxoplasma-infected DC did not exhibit upregulation of CD54/ICAM-1. Induction of host cell migration in vitro required live intracellular parasite(s) and was inhibited by uncoupling the Gi-protein signalling pathway with pertussis toxin, but did not depend on CCR5, CCR7 or Toll/interleukin-1 receptor signalling. When migration of Toxoplasma-infected DC was compared with migration of LPS-stimulated DC in vivo, similar or higher numbers of Toxoplasma-infected DC reached the mesenteric lymph nodes and spleen respectively. Adoptive transfer of Toxoplasma-infected DC resulted in more rapid dissemination of parasites to distant organs and in exacerbation of infection compared with inoculation with free parasites. Altogether, these findings show that Toxoplasma is able to subvert the regulation of host cell motility and likely exploits the host's natural pathways of cellular migration for parasite dissemination.

Adoptive Transfer↗

PubMed1977

Tazonomy of Toxoplasma.

After reviewing reports of the hosts, structure and life cycle of Toxoplasma, the genus is placed in the apicomplexan family Eimeriidae and the folllowing 7 species are recognized: Toxoplasma gondii (Nicolle & Manceaux) (type species) from about 200 species of mammals and birds, with oocysts in felids; Toxoplasma alencari (Da Costa & Pereira) from the frog Leptodactylus ocellatus; Toxoplasma brumpti Coutelen from the iguana Iguana tuberculata; Toxoplasma colubri Tibaldi from the snakes Coluber melanoleucus and Coluber viridiflavus; Toxoplasma hammondi (Frenkel & Dubey) (a new combination for Hammondia hammondi) from the house mouse with oocysts in the domestic cat; Toxoplasma ranae Levine & Nye from the leopard frog Rana Pipiens; and Toxoplasma serpai Scorza, Dagert & Iturriza Arocha from the toad Bufo marinus.

Animals↗

PubMed2002

[Survey of infection of Toxoplasma gondii in infertile couples in Suzhou countryside].

OBJECTIVES: To determine the level of anti-Toxoplasma antibody in serum of infertile couples to explore the relationship between toxoplasma infection and infertility. METHODS: Enzyme-linked immunosorbent assay (ELISA) was applied to detect the anti-Toxoplasma antibody, antisperm antibody (AsAb) and anticardiolipin antibody (ACA) in serum of 178 couples with infertility and 190 couples who had normal pregnant history. RESULTS: The positive result of Toxoplasma infection in the infertile couples was significantly higher than that in fertile couples which was 34.83% vs 12.11% (chi 2 = 26.72, P < 0.01) with the odds ratio 3.88. The positive result of serum AsAb in the Toxoplasma infected group was significantly higher than that in the no Toxoplasma infected group (32.50% vs 15.94%, chi 2 = 10.76, P < 0.01) with the odds ratio 2.54. CONCLUSIONS: Toxoplasma infection was related to infertility. The Toxoplasma infection and was posibly related to the antisperm antibodies which can be involved in the pathogenisis of infertility.

Animals↗

PubMed2003

[Expression, purification and serological reactivity of a chimeric antigen of GRA6 with P30 from Toxoplasma gondii].

Major surface protein (p30) and Dense Granule Antigen GRA6 of Toxoplasma gondii have good antigenicity, and could be used for detection of IgM against Toxoplasma gondii. GRA6 may complement P30 to reach more high sensitivity for detection of antibodies to Toxoplasma gondii, so, we try to express the chimeric protein of GRA6 and P30 by genetic engineering, identify its antignenicity and use for developing diagnosis reagent. Antigenic domains of p30 and GRA6 of Toxoplasma gondii were screened by analyzing their sequences using the software ANTHEWIN. Two DNA fragments encoding respectively antigenic domains of p30 and GRA6 were cloned, they were inserted into the same expression vector pET28a( + ) and expressed as a chimeric protein in Escherichia coli. BL21(DE3), the expressed chimeric protein of p30 with GRA6 in a form of inclusion body was about 25% of total proteins of E. coli. BL21(DE3). The inclusion body was washed once with 0.5% Triton X-100 and dissolved with 0.5% SKL, after renaturation by gradient dialysis, the recombinant protein was purified by DEAE-Sepharose FF cation column and then detected with 12% SDS-PAGE, it exists mainly in the eluted peak with 300 mmol/L NaCl and has high purity. By using enzyme-linked immunosorbent assay (ELISA), the recombinant protein was examined for reactivity with immunoglobulin M (IgM) antibodies in 6 sera from patients infected with Toxoplasma gondii ., it was reactive with all the 6 sera but not with sera from normal people, these results showed that the recombinant chimeric antigen has good antigenicity and specificity and could be used for detection of IgM against Toxoplasma gondii. The expressed chimeric protein could be used for epidemic investigation of Toxoplasma gondii, blood donor screening, especially for detection of pregnant women, and is of great significance in prevention of Toxoplasma gondii infection.

Animals↗

PubMed2005

Anti-Toxoplasma gondii antibodies in hemodialysis patients receiving long-term hemodialysis therapy in Turkey.

OBJECTIVE: Toxoplasma is a globally distributed pathogen for humans and animals. In situations of immunodeficiency, Toxoplasma gondii (T. gondii) emerges as a life-threatening infection. Toxoplasma gondii is transmitted parenterally, flourish in state immunosuppression and, most toxoplasma infections are asymptomatic. In the present study, we aimed to investigate the prevalence of anti-T. gondii antibodies in hemodialysis patients with chronic renal failure. We undertook a prospective study of our maintenance hemodialysis patients to determine whether these sources posed a risk for transmission of T. gondii. METHODS: This study was carried out on patients undergoing regular hemodialysis in the dialysis units (Hemodialysis Center of Antakya State Hospital, Emir Hemodialysis Center and Antakya Hemodialysis Center, Hatay, Turkey) between January 2004 and June 2004. Two hundred and fifty-five hemodialysis patients and 50 healthy controls were studied for the prevalence of anti-T. gondii antibodies by enzyme-linked immunosorbent assay. RESULTS: Anti-immunoglobulin G (IgG) and immunoglobulin M (IgM) T. gondii antibodies positivity were found to be 195 (76.5%) of the 255 hemodialysis patients and 24 (48%) of the 50 control subjects. The difference between them was statistically significant (p<0.05). In addition, an increase of the seropositivity rate was detected with increasing length of time on hemodialysis treatment, indicating a statistically significant difference between these 2 parameters (p<0.05). CONCLUSION: These findings confirm a high prevalence of toxoplasma infection in hemodialysis patients. These patients are a risk group for toxoplasma infection. Moreover, it is recommended that hemodialysis patients who are susceptible to toxoplasma infections should be identified by T. gondii IgG and IgM specific serological tests. Therefore, patients undergoing hemodialysis should be screened for toxoplasma before dialysis to prevent the dissemination of this infection through the hemodialysis procedure.

Adult↗

PubMed1998

Effects of drug therapy on Toxoplasma cysts in an animal model of acute and chronic disease.

PURPOSE: To evaluate the effects of drug therapy on the clinical course of acute acquired Toxoplasma retinochoroiditis and on the number of Toxoplasma cysts present in the brain and ocular tissues in the hamster animal model. METHODS: The Syrian golden hamster animal model of Toxoplasma retinochoroiditis was used. In acute disease, systemically administered atovaquone was compared with conventional therapies (pyrimethamine combined with sulfadiazine; clindamycin; and spiramycin). The clinical course of the ocular disease was determined with retinal examination and photography of the fundus. The number of Toxoplasma cysts remaining after treatment was evaluated in aliquots of brain homogenate and in retinal tissue. The effect of atovaquone on cerebral Toxoplasma cyst count was also studied in chronic disease. RESULTS: None of the drugs administered altered the course of the acute disease, judged by clinical examination. Atovaquone alone significantly reduced the number of cerebral Toxoplasma cysts after acute disease. Atovaquone also significantly reduced the cerebral Toxoplasma cyst count in chronic disease. CONCLUSIONS: Tissue cysts are believed to be responsible for reactivation of Toxoplasma retinochoroiditis. Atovaquone has the potential to reduce the risk of recurrent disease.

Acute Disease↗

PubMed1989

Aqueous humor analysis as a diagnostic tool in toxoplasma uveitis.

Analysis of local toxoplasma antibody production to confirm a suspected clinical diagnosis of toxoplasma chorioretinitis is a valuable diagnostic tool. Determination of toxoplasma antibodies in the blood of the patient is of limited use. When blood toxoplasma tests are negative this indicates that toxoplasma as a causative organisms in the pathogenesis of uveitis is unlikely. A positive blood test is a sensitive test (100% patients positive) but not a specific test since so many healthy individuals already have undergone subclinical infection and have acquired humoral immunity against the parasite. We analysed 93 paired aqueous and serum samples for toxoplasma antibodies and total IgG and determined the Goldmann-Wittmer coefficient. In patients retrospectively diagnosed as having toxoplasma chorioretinitis 16 out of 22 had a positive coefficient, indicating local parasite antibody production. In one patient with AIDS we also found a positive toxoplasma coefficient. Three out of 15 patients with posterior uveitis of unknown origin also had a positive coefficient. None of the cataract patients tested (n = 32) had a positive coefficient. Major drawbacks of aqueous humor analysis are that a false negative antibody coefficient can occur when a massive blood aqueous barrier breakdown has occurred.

Antibodies, Protozoan↗

PubMed2003

Decreased level of psychobiological factor novelty seeking and lower intelligence in men latently infected with the protozoan parasite Toxoplasma gondii Dopamine, a missing link between schizophrenia and toxoplasmosis?

Toxoplasma gondii, a parasitic protozoan, infects about 30-60% of people worldwide. The latent toxoplasmosis, i.e. life-long presence of cysts in the brain and muscular tissues, has no effect on human health. However, infected subjects score worse in psychomotor performance tests and have different personality profiles than Toxoplasma-negative subjects. The mechanism of this effect is unknown; however, it is supposed that presence of parasites' cysts in the brain induces an increase of the concentration of dopamine. Here we search for the existence of differences in personality profile between Toxoplasma-positive and Toxoplasma-negative subjects by testing 857 military conscripts using a modern psychobiological questionnaire, namely with Cloninger's Temperament and Character Inventory (TCI). ANCOVA showed that Toxoplasma-positive subjects had lower Novelty seeking (NS) scores (P=0.035) and lower scores for three of its four subscales, namely Impulsiveness (P=0.049), Extravagance (P=0.056) and Disorderliness (P=0.006) than the Toxoplasma-negative subjects. Differences between Toxoplasma-negative and positive subjects in NS was inversely correlated with duration of toxoplasmosis estimated on the basis of concentration anti-Toxoplasma antibodies (P=0.031). Unexpectedly, the infected subjects had also lower IQ (P(2)=0.003) and lower probability of achieving a higher education (P(2)<0.0000). Decrease of NS suggests that the increase of dopamine in brain of infected subjects can represent a missing link between toxoplasmosis and schizophrenia.

Adult↗

PubMed1994

Effect of Toxoplasma gondii upon neophobic behaviour in wild brown rats, Rattus norvegicus.

The effect of Toxoplasma gondii on neophobic behaviour (the avoidance of novel stimuli) was assessed in four groups of wild rats with naturally occurring Toxoplasma infection. Two groups were placed in individual cages and tested in a series of experiments which examined the effect of Toxoplasma on the rat's reaction to 3 food-related novel stimuli (odour, food-container, food). A trappability study was performed on the other two groups to test whether Toxoplasma had an effect on probability of capture. The results show that low neophobia was significantly associated with positive Toxoplasma titres in 3 out of 4 groups. We suggest that differences between infected and uninfected wild rats arise from pathological changes caused by Toxoplasma cysts in the brains of infected rats. Such behavioural changes may be selectively advantageous for the parasite as they may render Toxoplasma-infected rats more susceptible to predation by domestic cats (the definitive host of Toxoplasma) and, as a side-effect, more susceptible to trapping and poisoning during post control programmes.

Analysis of Variance↗