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A review of 58 patients in Singapore with significantly high anti-Toxoplasma serotitres.

Over a 42-month period, 58 patients presenting at the Singapore General Hospital were identified to have IgG anti-Toxoplasma serotitres of 1:1024 or higher by the indirect immunofluorescence test. This retrospective study examines the clinical presentation and management of these 58 patients. About 60% of these 58 patients had presented with lymphadenopathy, 20% with ocular symptoms and 14% with bad obstetric history. Almost all patients with IgG anti-Toxoplasma serotitres exceeding 1:1024 had presented with lymphadenopathy (with a modal titre of 1:4096). In contrast, most of the patients who presented with ocular symptoms or bad obstetric history had lower modal titres. The majority of patients who had presented with lymphadenopathy were Chinese, aged 21 to 35. Typically, they presented with a painless, mobile, solitary cervical node of three to four weeks duration as the only symptom, had biopsies where the histopathology was suggestive of toxoplasmosis, received no treatment and experienced no sequelae. The study concludes that: acute toxoplasmosis is common in Singapore and presents typically as asymptomatic cervical lymphadenopathy in a young Chinese; the incidence of congenital infection is also believed to be high, based on the number of cases presenting with fetal wastage and the prevalence of ocular toxoplasmosis; pigs in Singapore may constitute an important reservoir for the transmission of this disease to man.

Adult↗

[Antibodies against the cytomegalic virus and Toxoplasma gondii in a sample of the Monrovia population].

Cytomegalovirus and Toxoplasma gondii antibodies were titered in 133 serum specimens from students, physicians and technical staff of Monrovia hospital. The findings obtained show that both infections are widely spread: Cytomegalovirus antibody was detected in 81%, and Toxoplasma antibody in 70% of tested sera. No significative differences were observed among sera from different tribes and birth places.

Antibodies, Bacterial↗

Prevalence and isolation of Toxoplasma gondii from white-tailed deer in Alabama.

Nineteen white-tailed deer (Odocoileus virginianus) from 5 counties in Alabama were examined for infection with Toxoplasma gondii. Twenty-gram samples of heart tissue were bioassayed in mice, serum was examined for T. gondii antibodies using the direct agglutination test, and sections of heart muscle were examined histologically for tissue cysts. Toxoplasma gondii was isolated from 4 of 19 (21%) white-tailed deer hearts. Antibody titers of greater than or equal to 1:50 were found in sera from 7 of 16 (44%) white-tailed deer. Histological examinations of tissue sections from white-tailed deer hearts were negative for T. gondii.

Agglutination Tests↗

[Cytochemical study of different stages in the life cycle of Toxoplasma gondii. VII. Oxidation--reduction enzymes in the cyst forms].

Dehydrogenases of glycolysis, Kreb's cycle, and pentose-phosphate shunt were detected in cystozoites of Toxoplasma gondii strain SS-119 with various degrees of activity. A mixed oxidative metabolism may be postulated on this stage of the toxoplasma life cycle. Besides, the activity of cytochrome oxidase was detected in cystozoites; the addition of cytochrome c to the incubation medium significantly intensified the reaction intensity. Of interest seems the observation of a layer of higher enzymatic activity in the host brain tissue in the immediate neighbourhood with the cyst body. This may be regarded as the host cells' (or tissue') response to the presence of the parasite's alien body.

Dihydrolipoamide Dehydrogenase↗

Evaluation of ELISA for the detection of Toxoplasma antibodies in swine sera.

Enzyme-linked immunosorbent assay (ELISA) is compared with the indirect fluorescent antibody test (IFAT), the indirect haemagglutination test (IHAT) and the latex agglutination (LA) test for the detection of toxoplasma antibodies in swine sera. The 100 swine sera examined represent ELISA values from greater than 0 to 154 EIU. The agreement was highest (0.67) between ELISA and IFAT with an ELISA cut-off value of 30 EIU, and between ELISA and the LA test with an ELISA cut-off value of 50 EIU (0.74). All sera giving less than 10 EIU were negative in the other tests, and all those with greater than 70 EIU were positive in 1, 2 or all of the reference tests. In order to avoid false positive results with ELISA, all sera giving 10-70 EIU should be confirmed with a test which has a good specificity, e.g. IFAT. ELISA is a sensitive test and is highly suitable for the screening of large amounts of samples, but it may be too complicated for screening toxoplasma antibodies in the laboratories of abattoirs.

Animals↗

Increase of sulfadiazine effect against Toxoplasma gondii by using watermelon or cantaloupe seeds.

In an experimental model the anti--Toxoplasma effect of watermelon and cantaloupe seeds, together with sulfadiazine (Sd7.5 and Sd15) given by oral route, were studied. Combination of any of these seeds with the drug was able to increase the survival time and cure some tachyzoite infected mice. The effect was produced either by peeled or complete seeds and more significant results were obtained when Sd7.5 and 10(3) tachyzoite inoculum was used in the model. Some Toxoplasma oocyst infected mice were cured with the seeds alone (75% for watermelon, 37,5 or 50% for cantaloupe. Body weight variations are independent of the treatment with Sd alone or in combination with watermelon or cantaloupe seeds.

Animals↗

[Acute toxoplasmosis: evaluation of a thin-layer immunoassay technic for detection of IgM antibodies, anti-Toxoplasma gondii].

A solid phase method, thin-layer immunoassay (IgM-TIA) was standardized and evaluated for the immunodiagnosis of acute toxoplasmosis, through the detection of IgM antibodies to Toxoplasma gondii. A total of 300 serum samples from serologically defined acute toxoplasmosis and, from non-related infections, was investigated by IgM-TIA. Statistical analysis were carried out in comparison with conventional tests, the immunofluorescence test for the detection of IgM antibodies (IgM-IFI) and hemagglutination test which uses 2-mercaptoethanol serum treatment (2ME-HA). Also the correlation coefficients were calculated for various Toxoplasma gondii antigen concentrations, as well as, the influence of the antigenic concentration on the relative indices of sensitivity and specificity were verified. The intra and inter test reproducibilities were demonstrated statistically, as well as, the reutilization of T. gondii antigen was proven to be possible for at least 10 times. The data indicated that antigenic concentrations, from 70 to 100 Cmg/ml, were able to provide maximum sensitivity and specificity. IgM-TIA displayed similar diagnostic efficiency to those two conventional tests here utilized, and may be employed to make diagnosis of acute toxoplasmosis, mainly if laboratory animals are available.

Acute Disease↗

Acute primary toxoplasmic hepatitis in an adult cat shedding Toxoplasma gondii oocysts.

A 3-year-old 4-kg neutered male domestic shorthair cat died within 5 days after onset of fever and respiratory distress. At necropsy, all tissues were icteric, and the liver had a diffuse reticular pattern. Histologically, hepatitis and encephalitis were associated with Toxoplasma gondii tachyzoites. Toxoplasma gondii female gamonts and oocysts were found in epithelial cells of intact villi and in epithelial cells desquamated into the lumen. Finding of acute hepatitis and T gondii oocysts in an adult cat without detectable immunodeficiency is unusual, because adult cats rarely have clinical signs of toxoplasmosis during the oocyst-shedding phase.

Acute Disease↗

Prevalence of Toxoplasma gondii antibodies in dairy goats from 1982 to 1984.

Serum samples from 1,000 dairy goats from northwest United States (1982 to 1984) were examined for Toxoplasma gondii antibodies by a modified agglutination test. Toxoplasma gondii antibody titers were less than 1.40 for 779 goats, 1.40 for 153 goats, and greater than or equal to 1:400 for 68 goats. Seroprevalence increased with age of goats; 3.7% of 54 six-month-old goats were seropositive (greater than or equal to 1:40) vs 17.8% of 218 one-year-old goats.

Animals↗

Effect of high temperature on infectivity of Toxoplasma gondii tissue cysts in pork.

To study the effect of high temperature on infectivity of Toxoplasma gondii tissue cysts, pork from infected pigs was mixed with infected mouse brains and homogenized thoroughly. Twenty-gram samples of infected homogenized meat were sealed in plastic pouches, pressed to a uniform thickness of 2 mm, and subjected to water-bath temperatures of 49, 52, 55, 58, 61, 64, and 67 C for 0.01, 3, 6, 9, 12, 24, 48, and 96 min. Treated samples were digested in HCl-pepsin solution and bioassayed in mice. Toxoplasma gondii tissue cysts remained viable at 52 C for 9.5 min but not for 9.5 min at 58 C; tissue cysts were generally rendered nonviable by heating to 61 C or higher temperature for 3.6 min. Tissue cysts survived once at 64 C for 3 min. These data demonstrate that T. gondii tissue cysts are less heat resistant than encysted Trichinella spiralis larvae.

Animals↗

Induction of antigen-specific parasiticidal cytotoxic T cell splenocytes by a major membrane protein (P30) of Toxoplasma gondii.

Infection with Toxoplasma gondii has become a major cause of morbidity in patients with AIDS. To investigate the mechanisms responsible for immune responses to toxoplasma Ag we used a highly purified membrane protein (P30) of T. gondii to stimulate an in vitro Ag-specific cytotoxic T cell response. P30 immune mouse splenocytes reduced extracellular T. gondii plaque-forming units by more than 50% when incubated at an E/T ratio of 10:1 or greater. By using a [3H]uracil radioisotope release assay, the effect of the immune splenocytes was determined to be a direct parasite lytic mechanism. The immune splenocytes were P30 Ag specific and of the Thy 1.2, Lyt2,3+ (CD4-, CD8+) phenotype, specific for mouse cytotoxic T cells. Opsonization of the parasites with monoclonal P30-reactive mAb did not enhance parasiticidal activity. Culture supernatants obtained during the 2-h cytotoxic assay were not parasiticidal, and anti-asialo-GM1 antibody plus C did not destroy the parasiticidal activity of the P30 responder cells. Accordingly, we have identified an Ag-specific subset of CD4-, CD8+, P30 responder T cells that are directly parasiticidal to extracellular T. gondii, and that exhibit cytotoxicity independent of antibody opsonization, lymphokine secretion, NK cell activity, and, apparently, MHC involvement as well.

Animals↗

[Antigens of Toxoplasma gondii with a diagnostic and potential immunoprophylactic value: new strategies of identification].

Toxoplasma gondii is an ubiquitous protozoan parasite which induces severe pathology in in utero infected children and in immunosuppressed patients (particularly in the case of AIDS). Previous work that focused on toxoplasma somatic antigens failed to demonstrate an efficient protection against highly virulent T. gondii strains. The authors therefore first studied the role of parasite excreted-secreted (ES) antigens in the immune response. They describe here the preparation of excreted-secreted antigens in cell-free medium from tachyzoites, the intracellular proliferative stage present during acute infection. Major ES antigens have Mr of 108 K, 97 K, 86 K, 57 K, 42 K, 39 K, 28.5 K, 27 K and 21 K. The protective role of ES antigens has been demonstrated using congenitally athymic (Nu/Nu) rats that are highly sensitive to T. gondii infection (+/+ Fischer rats are resistant). The humoral and cellular components of this protection have been studied by the passive transfer either of sera or of T lymphocytes from ES-immunized +/+ Fischer rats into Nu/Nu rats. Adoptive transfers were carried out 24 hours before infection with the highly virulent T. gondii RH strain. Based on the concept of concomitant immunity, the authors have characterized antigens from tachyzoites and bradyzoites (the encysted stage persisting during chronic infection) which share common epitopes. Four tachyzoite antigens, P63, GP43, P39 and GP 28.5 have been shown by immunoprecipitation to cross-react with bradyzoite antigens. Two monoclonal antibodies raised against ES antigens permitted to demonstrate the localization of the 28.5 K and 27 K antigens inside the dense granules of tachyzoites and bradyzoites.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

[From the historical background of Toxoplasma gondii to the sero-immunological interpretation of the 30-yr results of a longitudinal study of newborn infants until 96 months of age].

The Author's study ranges from the historical background of Toxoplasma gondii to our current biological knowledge and the role of Toxoplasma gondii in pathology and human infection. The Author has considered the diagnosis--always problematic from the interpretative point of view--and, on the basis of his own long and extensive research, suggests the usefulness of a comparison with the results obtained from the dye test findings observed in longitudinal surveys of new born up to a maximum age of 96 months. The Author believes that these results can represent an element of comparison for the purpose of prognosis, therapy and prophylaxis, and above all, in sedation to combat anxiety states, and banal preoccupations.

Animals↗

[Antigen analysis of Toxoplasma gondii using chromatography, polyacrylamide gel electrophoresis and immunoprecipitation].

Whole (EAT), cytoplasmic (EAC) and membranous (EAM) extracts were prepared from Toxoplasma gondii RH Strain trophozoites by means of osmotic lysis and/or ultra sonication. Sephacryl S 300 gel chromatography shows respectively 5, 4 and 2 protein fractions from EAT, EAC and EAM. Polyacrylamide gel electrophoresis (PAGE) allowed to detect 22 proteins (WM from 6 to 130 Kd) from cytoplasmic extract and 3 proteins (MW: 8, 30 and 65 Kd) from membranous extract. Immunoprecipitation techniques were performed with polyclonal antibodies against Toxoplasma prepared from serum and rabbits immunized with EAT. Counter electro-immunodiffusion (CEID) on cellulose acetate membrane was found to be more sensitive than double immunodiffusion and immunoelectrophoresis as it detected 8 lines with both cytoplasmic and membranous extracts. The latter seem to be composed of large numbers of proteins which are present in very low quantities difficult to detect in PAGE, but very antigenic and easily shown by CEID.

Animals↗

[Detection of circulating antigens of Toxoplasma gondii using immunoprecipitation reactions in murine toxoplasmosis].

Circulating antigens (AGC) of Toxoplasma gondii were detected by counter electro-immunodiffusion (CEID) from the fourth day, in mice OF1 infected with 1,000 and 5,000 Toxoplasma gondii RH strain trophozoites. The mean number of precipitant lines increased from 1.6 on the fourth day to 5.8 on the seventh day, after which no animals survived. With the "Prugniaud" cystogenic strain no AGC were detected in mice inoculated with 100 and 200 cysts. Other techniques used, such as double immunodiffusion and immunoelectrophoresis, were shown to be less sensitive than CEID, and of little use for the detection of AGC. These AGC present antigenic similarities with some cytoplasmic fractions, particularly the FC3 fraction, and some membranous fractions such as FM1, separated by Sephacryl S300 gel chromatography.

Animals↗

[Toxoplasma antibodies in children in Slovakia with potential toxoplasmosis].

Over the years 1984-1987, 829 children from the Slovak Socialist Republic, aged from 0 to 15 years, with suspect toxoplasmosis were examined for the presence of toxoplasma antibodies by the serodiagnostic methods RVK, NIR, and ELISA. The percentage of toxoplasma antibodies yielded by the individual methods was as follows: RVK--39.5%; NIR--74.4%; ELISA-IgG--67.7%; ELISA-IgM--60.4%. Based on these results the authors conclude that the child population up to the age of 15 years is an at risk group with an increased possibility of contracting toxoplasmosis by frequent contact with the soil, sand, water, and animals, as well as by consuming not adequately cleaned fruit and vegetables. To protect the child population from toxoplasmosis greater attention is to be given to hygienic, nutritional and serodiagnostic prevention.

Adolescent↗

[Use of double McAb sandwich ELISA to detect circulating antigen of Toxoplasma in infected rabbits].

This paper reports on the cumulative positive frequencies of circulating antigen (CAg) detected in the sera of rabbits infected with Toxoplasma by using double-McAb sandwich ELISA. The positive frequencies of rabbits with heavy and medium infection in the incubation period are 30.8% and 11.1%. Those with medium infection in acute, subacute and early chronic period are 86.1% and 76.7%, 43.3% and 32.0% with light infection. The positive rates of CAg in rabbits of medium and light infection rose progressively in acute period, but declined in subacute and early chronic period. Cross reaction with schistosomiasis and coccidiosis was all negative. This method of high specificity, sensitivity and duplication possesses certain value in the diagnosis of acute or active Toxoplasma infection and may be useful for the diagnosis in the early period.

Animals↗

Longitudinal study of the specific humoral and cellular response to Toxoplasma gondii in a patient with acquired toxoplasmosis.

Specific cellular and humoral response to Toxoplasma were evaluated during a 2 yr follow up in a patient with acquired infection. Antibodies were titrated using conventional serological tests and analyzed by western blot technique. Analysis of the patterns obtained with IgA, IgG and IgM antibodies allowed a clear differentiation between acute and chronic stages of infection. Determination of lymphocyte subsets showed an important increase in the number of CD8 suppressive cells at the acute phase whereas CD4 cells remained within the normal range. Lymphocyte proliferation to Toxoplasma antigen was detectable one month after the onset of clinical symptoms and remained constantly positive. These results indicate that western blot analysis of antigens recognized by antibodies and determination of lymphocyte subsets may be helpful in the characterization of the infectious stage of acquired toxoplasmosis.

Adult↗