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PubMed1998

Seroprevalence of Toxoplasma gondii antibodies among Atayal aboriginal people and their hunting dogs in northeastern Taiwan.

Atayal aborigines, living at an altitude of 1,500-1,600 m in northeastern Taiwan, still hunt for wild animals with the help of hunting dogs. In this study, the latex agglutination test (LAT) was used to detect sera anti-toxoplasma antibodies in this community as a measure of their exposure to Toxoplasma gondii. The positive rates for sera anti-toxoplasma antibodies were 21.8% and 19.6%, respectively, in 422 Atayal and 51 hunting dogs tested. Neither of the positive rates were found to be significantly different between male (22.1%) and female Atayal (21.4%), or between humans (21.8%) and dogs (19.6%) (P > 0.05) when compared by the Chi-Squared test (chi 2-test). A significant difference was observed between the positive rates in adults (28.3%) and children (18.7%) (P < 0.05), and the age pattern of prevalence is consistent with an increasing duration of exposure to Toxoplasma gondii with age. The consumption of raw liver of wild animals or insufficiently cooked meat may be the major mode of transmission of toxoplasmosis in Atayal.

Adolescent↗

PubMedDate not supplied

Toxoplasma infection and cell free extract of the parasites are able to reverse multidrug resistance of mouse lymphoma and human gastric cancer cells in vitro.

A large number of compounds are known to reduce the ATP-dependent efflux pump activity of multidrug resistant (mdr) tumor cells. Here we report that an infection of cancer cells with T. gondii reduced the multidrug resistance of the tumour cells against cytostatic drugs. Two mouse lymphoma cell lines (Mdr L 5718 and Par 5718) were infected with Toxoplasma gondii in vitro and the reduction of efflux pump activity of the cells was measured. The drug accumulation (Rhodamin-123) was increased in the infected mdr cell lines compared with non- infected mdr-cells, and no effect was shown after infection of the parental cell line. The same effect was also achieved by incubation of Mdr-tumor cells with cell lysate of Toxoplasma gondii. Mdr-1-gene expression was reduced in the infected cell lines 48 hours after infection. Co-cultivation of Toxoplasma gondii with mdr cell lines separated by a microfilter from tumor cells was performed, but this cocultivation did not change the mdr efflux activity. The effect of Toxoplasma gondii infection on the efflux pump activity and mdr-1 gene expression was also examined in the human gastric cancer cells. A sensitization of resistant gastric cancer cells was also achieved by parasite infection. This phenomenon is an evidence that a reduction of resistance in tumor cells can be achieved by a natural parasite infection. It is as yet unclear whether an active infection or another substance of T. gondii is responsible for this phenomenon.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2000

High prevalence of antibody to Toxoplasma gondii among humans in Surabaya, Indonesia.

Infection with Toxoplasma gondii is of medical importance in relation to a recent increase in cases of acquired immunodeficiency syndrome (AIDS). In the present study, we surveyed antibody to Toxoplasma among 1,761 people in Surabaya, Indonesia. The overall prevalence was 58% with significant differences between males (63%) and females (52%; P < 0.001). Although antibody prevalences at 0-9 years in both genders were less than 10%, those at ages over 10 years were more than 50% in males or more than 40% in females, suggesting an extremely high transmission rate of the parasite to humans in this area. A bimodal pattern in the frequency distribution of Toxoplasma antibody levels suggested a persistent feature of Toxoplasma infection in humans.

Adolescent↗

PubMed2000

Seroprevalence of Toxoplasma gondii among pregnant women in Sweden.

BACKGROUND: Primary infection with Toxoplasma gondii during pregnancy can cause fetal infection with a risk of complications for the fetus. The proportion of women at risk of acquiring the infection during pregnancy in Sweden is not known. METHODS: The seroprevalence of Toxoplasma gondii among pregnant women in Sweden was calculated when 40,978 blood samples collected on filter paper eluates from newborns were tested for Toxoplasma specific immunoglobulin G. The newborns in two geographically different areas (Stockholm County and Skåne County) were investigated during a 16-month period between April 1997 and July 1998. The anti-toxoplasma IgG antibodies detected in the eluates were considered to be of maternal origin and to reflect the immune status of the mother. RESULTS: The seroprevalence was 14.0% in Stockholm County and 25.7% in Skåne County. The seroprevalence among women born in the Nordic countries was 11.1% in Stockholm and 24.9% in Skåne. The corresponding figures for women born outside the Nordic countries were 24.3% and 29.4%. On comparing the seroprevalence found in this study with older data, the overall seroprevalence in pregnant women born in the Nordic countries and living in Stockholm was found to have decreased between 1969 and 1998. The seroprevalence in different birth cohorts, longitudinally followed in the previous and the present studies, remained at the same level over 20 years despite the increasing age of the women. CONCLUSION: These results suggest that the majority of seropositive pregnant women in Sweden today have seroconverted before entering the childbearing period and that the percentage of women in Sweden acquiring toxoplasmosis during the childbearing period is low.

Adolescent↗

PubMed2001

Predictive value of latex agglutination test in serological screening for Toxoplasma gondii.

The predictive value of commercial latex agglutination kit (Toxo-Screen DA, bioMerieux) was assessed for use as screening test for Toxoplasma IgG antibody. The sensivity and specificity were also compared with those of the reference standard Sabin-Feldman dye test. Five hundred serum samples were collected from 200 blood donors and 100 each from pregnant women, kidney recipients and HIV infected persons. Eighty (16.0%) out of 500 subjects were positive for Toxoplama IgG antibody by Toxo-Screen DA (bioMerieux) compared with 57 (11.4%) by Sabin-Feldman dye test. The sensivity and specificity of Toxo-Screen DA (bioMerieux) were 100% and 94.8 % respectively which were similar to previous reports from the area of high prevalence of Toxoplasma infection. In present study the positive predictive value of Toxo-Screen DA (bioMerieux) was only 71.3%. The latex agglutination test should be considered as a screening test for Toxoplasma antibody, especially by small laboratories in remote area due to its availability, simplicity, sensitivity and specificity. However, because of its moderate positive predictive value, the test should be used with caution in screening immunocompromised patients and pregnant women living in areas with low prevalence of Toxoplasma infection. Since the number of false seropositive cases would be relatively higher than in a highly prevalent area, confirmation by the dye test would be needed.

Adolescent↗

PubMed1998

[Correlation between the dose and the anti-Toxoplasma effect of activated mouse macrophages induced by IFN-gamma and the synergism between IFN-gamma and TNF-alpha].

AIM: To find out the dose dependence of the anti-Toxoplasma effect induced by IFN-gamma and to determine the possible synergistic activity between TNF-alpha and IFN-gamma. METHODS: The in vitro effect of cultivated mouse peritoneal macrophages activated by IFN-gamma alone or IFN-gamma combined with different doses of TNF-alpha on the intracellular tachyzoites of RH strains and the nitric oxide (NO) level in the culture medium supernatant were simultaneously determined. RESULTS: With the increase in the dose of IFN-gamma, the anti-Toxoplasma effect was augmented and the NO level was enhanced. At 24 hours after tachyzoite invasion, a significant reversed correlation was demonstrated between the NO level and the number of intracellular parasites. CONCLUSION: The anti-Toxoplasma effect of macrophages activated by IFN-gamma appears to be dose-dependent and TNF-alpha acts synergitically with IFN-gamma in the activation of macrophages. The production of reactive NO could be an important effector in the IFN-gamma primed anti-Toxoplasma action.

Animals↗

PubMed1992

Seroepidemiology of Toxoplasma infection in Riyadh, Saudi Arabia.

A total of 362 apparently healthy Saudis of both sexes living in Riyadh and aged 4-60 years, were investigated for Toxoplasma antibodies using the indirect haemagglutination test (IHT). Eighty one (22.4%) were positive with titres of 1/64 or greater. A significantly higher prevalence of Toxoplasma antibodies was correlated with age and association with cats. Economic status showed an apparent, but not significant, negative correlation with antibody prevalence rates. No significant association was found between Toxoplasma infection and sex, consumption of raw or undercooked meat, and urban or rural residence. The results provide an evidence that cats may be the main source of human infection with Toxoplasma in Riyadh.

Adolescent↗

PubMed2003

[Cloning and expression of the signaling protein 14-3-3 of Toxoplasma gondii].

OBJECTIVE: To clone and express the cell signaling protein 14-3-3 gene from Toxoplasma gondii RH strain. METHODS: Toxoplasma RH strain tachyzoites, which maintained by mouse passage, were harvested from ascites of mice and genomic DNA was prepared. A pair of primers were designed and synthesized based on the sequence of Toxo 14-3-3 cDNA. A specific fragment of Toxo 14-3-3 gene was obtained by RT-PCR amplification from Toxoplasma genomic DNA. The PCR products were ligated to pGEM-T. The EcoRI/Xho I restricted fragments, confirmed by PCR and EcoRI/XhoI digestion, were cloned into expression vector pET28a and the recombinants were transformed into E. coli BL21. Fusion expression was induced by isopropyl-beta-D-thiogalactoside (IPTG) and confirmed by Western blotting with rabbit anti-Toxoplasma sera. RESULTS: The molecular size of Toxo 14-3-3 was 803 bp, which is highly homologous to the previous report cloned from the parasites of intestinal epithelial stage in cat. High expression was obtained in pET28a/Toxo 14-3-3/E. coli BL21 when confirmed by Western blotting. CONCLUSION: The recombinant construction of Toxo 14-3-3 was generated and expression was induced.

14-3-3 Proteins↗

PubMed1992

[Intraocular diseases and toxoplasma infection--a matched case-control study].

A matched case-control study was used to identify the relation between intraocular diseases and toxoplasma infection. We found 37 (36.6%) out of 101 patients with intraocular diseases to be toxoplasma IgG antibody positive, while 21 control patients (20.7%) to be antibody positive against the same organism (P less than 0.05, OR = 2.14, EF1 = 0.192). 27 (36.5%) out of 74 patients with uveitis and 11 (14.9%) out of 74 matched patients were toxoplasma IgG antibody positive respectively (P less than 0.01, OR = 3, EF2 = 0.23). The toxoplasma infection as an important factor in patients with intraocular diseases is suggested by the results.

Animals↗

PubMed1992

Serologic response of the opossum Didelphis virginiana to a temperature-sensitive mutant (ts-4) of Toxoplasma gondii.

A study was designed to measure the Toxoplasma gondii-specific IgM and IgG antibody responses of opossums inoculated with tachyzoites of the temperature-sensitive mutant of T. gondii, ts-4, and to examine its persistence in the tissues. Four young opossums seronegative for anti-Toxoplasma gondii IgM and IgG antibodies immediately after capture and 4 wk later were injected subcutaneously with 1.8 x 10(6) ts-4 tachyzoites; a fifth opossum (also seronegative) received an injection of saline only. Serum was collected weekly and titered by modified direct agglutination for anti-Toxoplasma gondii IgM and IgG. IgM titers were detectable from week 1 to week 6 postinoculation (PI). IgG was measurable by week 3 and remained high for 30 wk PI when the opossums were killed and examined. The control opossum did not develop a specific antibody response. At necropsy major lesions were not found. No anti-Toxoplasma gondii IgG was detected in serum collected from mice injected with tissues prepared from the opossums at necropsy, and no T. gondii was found on impression smears made at necropsy from these mice. Modified direct agglutination performed with or without 0.2 M 2-mercaptoethanol worked well for measuring specific IgM and IgG antibodies in experimentally infected opossums.

Agglutination Tests↗

PubMed1991

[Problems in the demonstration of Toxoplasma gondii in muscle tissue of sheep].

It is a known fact that sheep usually show a high level of infection with the parasite Toxoplasma gondii. Samples of five grams of muscular tissue taken from the diaphragms of forty sheep were digested with trypsin. The digested material was microscopically examined for bradyzoites of Toxoplasma using the Giemsa-staining method and a Toxoplasma-specific immunofluorescence test. In spite of the fact that antibodies were detected with the ELISA in sixty-five percent of the sheep, Toxoplasma could not be identified in any of the samples of muscular tissue.

Animals↗

PubMedDate not supplied

[Effect of table salt on Toxoplasma gondii].

UNLABELLED: Results of our inquiry on Toxoplasma gondii frequency in pork sausages from Erechim (RS, Brazil), where the incidence of toxoplasmotic chorioretinitis is high (9% according Silveira, 1987), revealed only one isolation of the parasite among 40 sausage samples. (Martins, 1989). The sausages were prepared with pork and common table salt, and were ingested, frequently, in raw state, during its preparation. In this experiment, table salt action on tachyzoites and cysts of Toxoplasma gondii, was investigated. Albino male mice were intraperitoneally inoculated with 0.5 ml of peritoneal exsudates (tachyzoites) or brain macerates (cysts) from previously infected mice. Some strains were isolated from pork and pork sausages from Erechim. Refined common table salt was added to the inocula at 2.2%, 2.5% and 3.0% concentrations, during 24 and 48 hours, 3-5 and 7 days of exposition time, at 4 degrees C. The results demonstrated that at 2.2%, 2.5% and 3.0% salt concentrations and 24 and 48 hours of time exposition all mice inoculated with tachyzoites were dead, except one, probably not infected. At 3.0% and 3-5 and 7 days of contact, 10 in 37 inoculated mice survived (27%). Of the mice inoculated with cysts plus salt at 3.0%, at 5 and 7 days exposition, 85% survived (17 in 20). All the controls mice inoculated with the same inocula without salt, at the same conditions, died earlier than the test mice. The Toxoplasma was recovered from peritoneal exsudates and brains of recently dead and dying mice, but not from the survivors. CONCLUSION: the table salt has an inactive action on Toxoplasma gondii in 3.0% concentration and at 3 to 7 days exposition.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Prevalence of Toxoplasma gondii antibodies among children and teenagers in Italy.

Between 1987 and 1989, the prevalence of antibodies to Toxoplasma gondii was determined by ELISA in serum samples from 1,494 apparently healthy subjects, 3-18 years old. Subjects were selected by a systematic cluster sampling from five geographical areas in Italy. The overall prevalence of antibodies was 17.9%, increasing from 4.7% in 4-6 year olds to 28.4% in 17-18 year olds (P less than 0.01). A slight predominance was observed among males (18.2% vs. 17.5% in females), as well as among subjects residing in Southern Italy and the Islands (21.9% vs. 19.2% in subjects residing in the North), but neither difference was statistically significant. Toxoplasma infection was associated with sociodemographic factors. Subjects belonging to a household with six or more persons had a 1.8-fold risk (C.I. 95% = 1.3-2.6) and subjects whose fathers had less than six years of schooling had a 2.7-fold rosk (C.I. 95% = 1.8-3.9) of previous exposure to toxoplasma infection. Considering the large proportion (70%) of young women entering childbearing age without toxoplasma antibodies, it appears that the risk of congenital toxoplasmosis will not be negligible in Italy in forthcoming years.

Adolescent↗

PubMed1991

Toxoplasma gondii infections in red-tailed hawks inoculated orally with tissue cysts.

The response to inoculation of Toxoplasma gondii tissue cysts was examined in 3 red-tailed hawks (Buteo jamaicensis). One hawk (hawk 1) was inoculated orally with 3.000 tissue cysts of the GT-1 isolate of T. gondii and 2 hawks (hawks 2 and 3) each were inoculated orally with 12,000 tissue cysts of a mixture of 8 isolates of T. gondii. None of the hawks developed clinical signs of toxoplasmosis. Serum antibodies were measured with the modified direct agglutination test using formalin-fixed tachyzoites. Hawk 1 had a titer of 1:40 prior to inoculation and did not have an increase in titer during the study. Hawks 2 and 3 had titers of 1:5 and 1:10, respectively, prior to inoculation, and both had increased titers (titers greater than or equal to 1:60) by 1 wk postinoculation and remained T. gondii antibody positive throughout the 10 wk of the study. Toxoplasma gondii was isolated from the heart and breast muscle of hawk 1. The biologic behavior of this T. gondii isolate was different from the 1 inoculated, and it probably represents a prior natural infection. Toxoplasma gondii was isolated from the brain, heart, breast muscle, and a mixture of gizzard and proventriculus from hawk 2 and from breast muscle of hawk 3. Toxoplasma gondii was not isolated from the eye, lung, liver, kidney, or spleen of any red-tailed hawk.

Agglutination Tests↗

PubMedDate not supplied

[Isolation of Toxoplasma gondii from the saliva of patients with acquired immunodeficiency syndrome (AIDS)].

Toxoplasma gondii has been found in saliva of patients with toxoplasmosis. We tried to isolate parasites in saliva in patients with AIDS. As it is known, the finding of antitoxoplasma antibodies is not useful for diagnosis of cerebral abscess in toxoplasmosis occurring in AIDS patients in Brazil where 90% or more adults have serological evidence of past infection with Toxoplasma gondii. In 26 patients with AIDS, including six with tomographical evidence suggesting cerebral abscess caused by Toxoplasma gondii, no parasites were found in the saliva by the use of the mouse inoculation model. This trial that the search for Toxoplasma gondii in the saliva is not an alternative method for the diagnosis of toxoplasmosis in patients with AIDS.

Acquired Immunodeficiency Syndrome↗

PubMed1990

Microbiostatic effect of murine-activated macrophages for Toxoplasma gondii. Role for synthesis of inorganic nitrogen oxides from L-arginine.

Recent studies show the importance of a single amino acid, L-arginine, as a necessary substrate for activated macrophage-mediated cytotoxic activity for tumor target cells and microbiostatic function for Cryptococcus neoformans. The present studies were carried out to determine the role of the L-arginine-dependent macrophage effector function on the microbiostatic effects of activated macrophages on the obligate intracellular protozoan, Toxoplasma gondii. A guanidino methylated derivative of L-arginine, NGmonomethyl-L-arginine (NGMMA), a competitive inhibitor of the L-arginine-dependent effector pathway, virtually abolished the normally potent microbiostatic effect of macrophages for Toxoplasma gondii after activation of the macrophages in vitro by IFN-gamma and LPS or in vivo by i.p. injection of killed Corynebacterium parvum. Addition of supplemental L-arginine to the culture medium overcame the capacity of NGMMA to block activated macrophage-mediated microbiostasis of Toxoplasma. The ability of NGMMA to inhibit the microbiostatic capacity of activated macrophages for Toxoplasma gondii correlated with almost total inhibition of synthesis of nitrite, nitrate, and L-citrulline from L-arginine. Therefore, as is the case for tumor target cells and C. neoformans, the synthesis of inorganic nitrogen oxides from a terminal guanidino nitrogen atom of L-arginine appears to be essential for murine cytotoxic activated macrophage mediated microbiostatic capacity for T. gondii.

Animals↗

PubMed1989

Diagnosis of recent Toxoplasma gondii infection in cats by use of an enzyme-linked immunosorbent assay for immunoglobulin M.

Subclinical Toxoplasma gondii infection was induced in young and adult cats by oral administration of tissue cysts. An antibody-capture ELISA to detect anti-Toxoplasma IgM-class antibodies in the serum of cats was developed. The serologic response to experimental infection was followed in the 2 groups of cats by use of anti-Toxoplasma IgM and IgG detection. This study shows that anti-Toxoplasma IgM-class antibody titers develop early in the course of experimental infection in cats and that the combination of IgM- and IgG-class antibody titer measurement can aid in the detection of recent subclinical toxoplasmosis.

Animals↗

PubMed1985

Human mononuclear phagocyte antiprotozoal mechanisms: oxygen-dependent vs oxygen-independent activity against intracellular Toxoplasma gondii.

To determine if the oxygen-dependent and -independent antiprotozoal mechanisms with which the human mononuclear phagocyte is equipped to act against Leishmania donovani operate against other intracellular parasites, oxidatively intact and deficient cells were challenged with Toxoplasma gondii. Fresh monocytes and lymphokine- or gamma-interferon (IFN-gamma)-activated macrophages from normal individuals killed 35% and 50% of T. gondii within 6 hr, respectively, and each of these cell populations inhibited the replication of surviving parasites 20 hr after infection. This activity was associated with the capacity to release large amounts of H2O2 (572 to 971 nmol/mg) and to respond to toxoplasma ingestion with respiratory burst activity. Impairing the ability to generate oxygen intermediates by glucose deprivation or treatment with superoxide dismutase, catalase, or mannitol inhibited toxoplasmacidal activity by greater than 80% and permitted a 2.6- to 4.3-fold increase in the number of intracellular toxoplasmas. In contrast to normal cells, fresh monocytes from patients with chronic granulomatous disease (CGD) killed less than 8% of toxoplasmas and exerted 50% less toxoplasmastatic activity. However, although associated with the induction of only modest toxoplasmacidal effects (18 to 20% killing), lymphokine stimulation did induce CGD monocytes and macrophages as well as oxidatively inactive human endothelial cells to display near normal levels of toxoplasmastatic activity. Similar to oxygen-dependent mechanisms, the enhancement of oxygen-independent activity by crude lymphokines could be abolished by a monoclonal anti-IFN-gamma antibody and could be achieved by treatment with recombinant IFN-gamma alone. Unstimulated CGD monocytes, however, were found to lose all antitoxoplasma activity after two days in culture, whereas normal cells continued to effectively inhibit T. gondii replication, suggesting that oxygen-independent responses may not actually be required for the normal monocyte to act against T. gondii. Taken together with previous findings with L. donovani, these results indicate that the human mononuclear phagocyte possesses an oxygen-independent antiprotozoal mechanism and that its effects can be enhanced by lymphokines (IFN-gamma), but that nevertheless this cell's primary response to intracellular protozoa is largely oxygen dependent.

Endothelium↗