Diagnosis Of Acute Toxoplasmosis Research Articles

Diagnosis of acute toxoplasmosis in an immunocompetent patient by isolation of the agent and immunohistochemistry from lymph node biopsy

Diagnosis of acute toxoplasmosis in an immunocompetent patient by isolation of the agent and immunohistochemistry from lymph node biopsy

Application of neural networks to the real-time diagnosis of acute toxoplasmic infection in immunocompetent patients.

Neural networks constitute a relatively new, radically different approach to the interpretation and recognition of subtle diagnostic patterns in multivariate data. In this study the use of neural networks with a single serum sample for rapid real-time recognition of recent toxoplasmic infection was investigated. A neural-network model was implemented on the basis of data obtained by four serological methods--dye test, indirect fluorescence assay, indirect hemagglutination assay, and IgM immunosorbent agglutination assay--and was "trained" to extract features of acute infection by application to an analysis of 65 immunocompetent patients, 10 of whom were in fact acutely infected. The trained model correctly classified all 10 cases of acute infection. On its application to 61 additional infected patients, this method correctly identified seven cases as potentially acute. Our study shows that neural networks can discern diagnostic patterns from variables that individually have limited utility in the diagnosis of acute toxoplasmosis.

Detection of Circulating Antigens in the Diagnosis of Acute toxoplasmosis

Using an enzyme-linked immunosorbent assay, we have found circulating antigens of Toxoplasma gondii in three models of murine toxoplasmosis: mice infected with trophozoites of the RH strain (acute toxoplasmosis), the Beverley strain (subacute toxoplasmosis), and the T626 strain (chronic toxoplasmosis). Circulating antigens were detected 48 hr after infection in the mice infected with the RH strain, and all mice had antigenemia by the fourth day. In those infected with the Beverley strain, circulating antigens were detected from the second day after inoculation until the end of the study, with a peak (71% of the infected mice) on day 10. Of those infected with the T626 strain, 40% had antigenemia at 13 days after infection. The detection of circulating antigens in serum is directly related to the presence of toxoplasmosis in the acute phase in the three models studied and, therefore, may prove very useful in the rapid diagnosis of this disease.

Diagnostic Parasitology

Diagnosis of parasitic infections in small animals is challenging, interesting, and fun, and involves the recognition of parasite stages based on size, morphology, color, and movement. Size and morphology are the major diagnostic parameters, and a calibrated microscope is the essential tool in the diagnostic laboratory. The fecal flotation technique is used routinely for the diagnosis of most parasites that reside within the gastrointestinal tract. The specific gravity and type of solution used often will influence the results obtained. A sugar flotation solution with a specific gravity of 1.27 is one that will float a majority of parasite stages with minimal distortion. Other techniques for diagnosis of specific gastrointestinal parasites include the direct smear and the merthiolate-iodine-formalin preservative method for diagnosis of Giardia sp, the Baermann technique for diagnosis of lungworm and other live larvae, the direct sedimentation technique for diagnosis of trematode eggs, the ether-formalin-sedimentation technique for diagnosis of trematode eggs and concentrating protozoan cysts from feces with high fat content, and the McMaster technique, a dilution modification of the fecal flotation technique. Techniques for evaluation of parasites in blood include the Knott's test, hematocrit method, and direct blood smear for diagnosis of microfilariae and thick and thin stained blood smears for diagnosis of Babesia sp, Haemobartonella sp, Cytauxzoon felis, Hepatozoon canis, and Trypanosoma cruzi. Tissue impression smears are used commonly for the diagnosis of Leishmania sp in dogs and biopsy specimens or aspirates are used for the diagnosis of Pneumocystis carinii. Diagnosis of acute toxoplasmosis can be accomplished with peritoneal and thoracic fluids, and organisms occasionally are detected in blood or spinal fluid. Serological tests for many parasitic diseases have been developed and often are used as supportive diagnostic tests.

Lectins for the detection of IgM antibodies to T. gondii in the diagnosis of acute toxoplasmosis by immunofluorescence test

Lectins were labeled with fluorescein and tried as conjugates in the immunofluorescence (IP) test for the detection of IgM antibodies to T. gondii, in the diagnosis of acute toxoplasmosis. This approach was an attempt to find alternative reagents for anti-human IgM fluorescent conjugates (AHIgMFC), which contain quite frequently anaibcdies to toxoplasma, as contaminants, due to natural T. gondii infections among animals used for imunization. Lentil (Lens culinaris) lectin fluorescence conjugates (LcFC) provided most satisfactory results. The evaluation of LcFC carried out in a total of 179 sera from patients with acute and chronic toxoplasmosis, with non-related infections or healthy subjects, gave high values of relative efficiency, co-positivity and co-negativity indices, respectively 0.989, 0.969 and 1.000, in reference to the conventional AHIgMFC. Moreover, three batches of LcFC successively prepared gave reproducible test results. The advantage of LcFC as an alternative reagent for the serodiagnosis of acute toxoplasmosis is supported by practical aspects of its preparation.

Cerebral toxoplasmosis in a patient with Hodgkin's disease

A case is described of a patient presenting with enlarged lymph nodes and in whom a diagnosis of acute toxoplasmosis was made. The patient later developed Hodgkin's disease for which chemotherapy was started. Reactivation of the quiescent toxoplasma infection took place with devastating results. Prophylactic treatment in such cases is discussed.

Diagnosis of acute toxoplasmosis by an enzyme immunoassay for specific immunoglobulin m antibodies.

A recently developed enzyme-linked immunosorbent assay for detection of immunoglobulin M (IgM) class antibodies to Toxoplasma gondii was evaluated with respect to specificity and sensitivity. By using an antibody capture principle and F(ab')2 conjugates, interference of rheumatoid factors was absent. No cross-reactions with anti-toxoplasma IgG occurred, and no interference with antinuclear antibodies was found. A large-scale study with about 1,500 clinical specimens revealed a 100% specificity. By testing 79 sera from patients with acute-phase acquired toxoplasmosis, sensitivity was found to be 97%. In routine clinical practice, the IgM-enzyme-linked immunosorbent assay proved to be a more sensitive tool for diagnosis than the immunofluorescent-antibody test. The course of IgM-enzyme-linked immunosorbent assay antibodies in acute patients was studied; IgM reached peak levels within 1 month after onset of illness, and could be demonstrated up to an average of 8 months after onset.