Risk Of Toxoplasmosis Research Articles

Evaluation of risk and diagnostic value of quantitative assays for anti-Toxoplasma gondii immunoglobulin A (IgA), IgE, and IgM and analytical study of specific IgG in immunodeficient patients

To determine their prognostic and diagnostic values for toxoplasmosis in immunodepressed subjects, we assayed immunoglobulin A (IgA) and IgE antibodies by means of immunocapture (IC) tests, with revelation done by using a suspension of T. gondii (ICT). We also carried out a simultaneous analytical study of IgG antibodies on cellulose acetate membranes by using the comparative immunological profile method and an enzyme-linked immunofiltration assay (ELIFA). A total of 1,238 samples (serum, cerebrospinal fluid, and aqueous humor from 318 patients) were tested. IgA and IgE antibodies were detected in all heart, kidney, and liver transplant recipients with clinical manifestations of toxoplasmosis; IgA was detected in the aqueous humor of a patient with chorioretinitis. In patients with AIDS-related toxoplasmosis, including the cerebral form, IgA and IgE antibodies or a significant modification of ELIFA IgG values were observed in 38, 19, and 25% of patients, respectively. IgM was detected by ICT only in 12% of patients and aided the diagnosis in 1 of 71 patients. IC tests for specific IgA and IgE alone and combined with ELIFA were positive in 39 and 46% of patients who developed clinical toxoplasmosis, respectively. In a serial study of 16 patients in whom at least one of these three tests was positive, a significant immunological signal sometimes preceded clinical onset by 1, 6, and even 17 months. Similarly, in a group of human immunodeficiency virus-infected patients with evidence of previous exposure to T. gondii but no clinical manifestations, IgA, IgE, and IgA and/or IgE antibodies were detected in only 11, 4, and 12% of patients, respectively. These two situations point to peripheral T. gondii reactivation. IgA and IgE emerged as interesting markers of the risk of toxoplasmosis in immunodepressed patients. They may also provide valuable assistance in the diagnosis of toxoplasmosis, especially because tests for specific IgM are disappointing. However, at least one in two patients with toxoplasmosis showed no detectable immunological reaction, suggesting that this polyisotypic approach should be combined with other noninvasive methods such as gene amplification.

Risk factors for severe disease due to Toxoplasma gondii in HIV-positive patients

The objective of this study was to assess the risk of toxoplasmosis in HIV-positive subjects as a basis for primary prophylaxis. A retrospective chart review of 400 consecutive patients was carried out and clinical and laboratory markers at first presentation and follow-up data on the occurrence of toxoplasmosis were recorded. Independent variables were identified, laboratory parameters were stratified, and estimates for the risk of toxoplasmosis and the impact of different variables on its occurrence were made using conventional statistical methods. An increased risk of toxoplasmosis was strongly associated with a positive Toxoplasma gondii IgG EIA in conjunction with a CD4+ cell cont below 0.15/nl (the estimated risk of toxoplasmosis was 20% and 35% after 12 and 24 months, respectively) or a history of one or more opportunistic infections (the estimated risk was 12% and 30% after 12 and 24 months, respectively). Toxoplasma gondii-seropositive patients with CD4+ cell counts below 0.15/nl and those with antecedent opportunistic infections are most likely to develop toxoplasmosis and thus might benefit from primary prophylaxis. The risk of disease probably outweighs the risk of medication in these subjects. Prospective clinical trials are needed to define the optimal choice of drugs.

Cats and toxoplasmosis risk in HIV-infected adults

Cats and toxoplasmosis risk in HIV-infected adults

Cats and Toxoplasmosis Risk in HIV-Infected Adults

To establish the prevalence and incidence of toxoplasmosis in an adult human immunodeficiency virus (HIV) population, and to determine if cat ownership contributes to the risk of toxoplasmosis. Retrospective record and laboratory review, coupled with a patient survey. A tertiary-care military hospital HIV program. A total of 723 HIV-infected adults, all former or current US military personnel. Prevalence and incidence of serologic evidence of toxoplasmosis infection. A total of 723 HIV-infected patients had serial Toxoplasma IgG antibody determinations. Seventy patients (9.7%) were positive on their initial screen; the seronegative patients were tested annually for 1 to 5 years (mean duration of follow-up, 2.1 years). Only 13 patients (2.0%) who were initially seronegative acquired antibodies to Toxoplasma gondii. None of the patients who seroconverted developed clinical disease. A pet history was available on 12 of 13 patients who seroconverted; only one (8.3%) had owned or lived in a household with a cat during the period of seroconversion. The calculated attributable risk of cat ownership/exposure for toxoplasmosis seroconversion in this population is -2.9 per 100 persons annually. Toxoplasma antibody seroconversion in an adult HIV-infected population is unusual and appears unrelated to cat ownership or exposure.

Contact with pigs and cats associated with high prevalence of Toxoplasma antibodies among farmers.

Antibodies to Toxoplasma were measured by enzyme linked immunosorbent assay (ELISA) in sera from 159 abattoir workers, 142 pig farmers, and 106 grain or berry farmers. Farmers occupationally exposed to pigs had antibodies in 53 (37%) cases, abattoir workers in 40 (25%) cases, and farmers not exposed to pigs in 24 (23%) cases. In each group antibodies were more prevalent among those who had a cat or cats in the household. Controlling for age and cat contacts changed the prevalences less than one percent. The results indicate that pig farmers might have an occupational risk of toxoplasmosis. As the prevalence of antibodies among abattoir workers was about the same as among the referent farmers, it seems unlikely that infection from Toxoplasma could be acquired by mere handling of raw meat.

Treatment and results of chronic toxoplasmosis. Analysis of 33 cases.

Women who grew up in Turkey, where undercooked meat is part of the usual diet, have an increased risk of toxoplasmosis. This study covers treatment and prognosis of 33 cases with chronic toxoplasmosis. The study group was selected among the patients with a history of repeated abortions, recurrent preterm labor, stillbirths and babies with congenital anomaly after all other causative reasons were ruled out. IgG and IgM antibody titers were detected by Sabin-Feldman's dye test and indirect fluorescence antibody test. 33 patients, who had negative IgM and IgG antibody titers above 1/64, were accepted as having chronic toxoplasmosis and were included in our study group. These patients were treated with our pyrimethamine treatment protocol (Dinçer Formula) for 36 days before their pregnancies. IgG antibody titers were repeated in the 8th and the 20th week of pregnancy. With the exception of 7 cases, 24 patients (72.7%) still had IgG antibody titers of more than 1/64 and were given the same treatment protocol in the 8th week of pregnancy. Very early abortions occurred in 2 cases. Of 24 patients, 8 had antibody titers still above 1/64 and were treated with spiramycine. While 28 cases (84.8%) had healthy and living infants, pregnancies of 3 cases are still continuing. No teratogenic effects of pyrimethamine on the fetuses were seen. As a result, we can say that a patient who presents with complaints of repeated abortions, recurrent preterm labor or stillbirth should be investigated for toxoplasmosis during pregnancy; even if the IgG antibody test is normal before pregnancy, she should be treated with the protocol mentioned above before pregnancy and in the 8th week of pregnancy when chronic toxoplasmosis is diagnosed.

THE EFFECTS OF VYCLOSPORINE ON TOXOPLASMA GONDII IN VIVO AN IN VITRO

We examined the effect of cyclosporine on Toxoplasma infection in vivo and in vitro. Administration to mice of 150 mg/kg/day cyclosporine variably affected mortality in four separate experiments. IgG (Sabin-Feldman dye test) and IgM enzyme-linked immunosorbent assay antibody titers were significantly depressed in mice treated with cyclosporine. These results suggested the possibility that cyclosporine possesses anti-Toxoplasma activity. Thus, macrophages were incubated with cyclosporine before and after infection with Toxoplasma. Treatment with 0.5, 1, and 5 micrograms cyclosporine/ml during or after challenge of macrophage monolayers with Toxoplasma inhibited replication of Toxoplasma (and resulted in killing of Toxoplasma). The effect of cyclosporine on development of activated macrophages was studied. Cyclosporine administered to mice at a dose of 150 mg/kg/day neither accelerated nor delayed activation of macrophages (assessed by inhibition of Toxoplasma replication in vitro) by i.v. injection of either Corynebacterium parvum or Toxoplasma. Cyclosporine affects mortality variably in murine toxoplasmosis, depresses synthesis of IgG and IgM Toxoplasma antibody in vivo, does not prevent activation of macrophages in vivo, and possesses anti-Toxoplasma activity in vitro and perhaps in vivo. Cyclosporine may be the preferred immunosuppressive agent for recipients of an organ transplant who are at high risk for toxoplasmosis (e.g., seronegative recipients who have received organ from seropositive donors).