Medical expert of the article
New publications
Toxoplasmosis - Diagnosis
Last reviewed: 03.07.2025
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
Clinical diagnostics of toxoplasmosis
Diagnosis of toxoplasmosis is based on epidemiological risk factors for infection and clinical and laboratory diagnostic data.
[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ]
Specific and non-specific laboratory diagnostics of toxoplasmosis
Parasitological diagnostics of toxoplasmosis (examination of biopsies of lymph nodes and other organs) has not found wide application due to its complexity and labor intensity. Microscopy, direct version of the fluorescence analysis method (DAM) and the method of bioassays on white mice with the isolation of T. gondii are used to detect toxoplasma. The immunoblotting method for detecting the proteins of the pathogen with IgM, IgG, IgA antibodies and the polymerase chain reaction have been developed. Diagnostics of intrauterine toxoplasmosis is based on the methods of cordocentesis and amniocentesis. However, these methods have limited application in practical medicine, since they are expensive, require special equipment and certain personnel training.
In the vast majority of cases, toxoplasmosis diagnostics involves the use of serological tests. Serological diagnostics of toxoplasmosis is based on the detection of Ig classes G, M, A, E. They can be determined by the indirect method of fluorescent antibodies (IMFA), solid-phase enzyme immunoassay (SPE), etc. Among the modern methods of toxoplasmosis serodiagnostics, differential agglutination tests, latex agglutination tests, and trap SPE to detect IgM to toxoplasma are also used. Such tests for determining antibodies as the precipitation reaction (PR), complement fixation reaction (CFR), and indirect hemagglutination (IHA) are currently rarely used due to their low sensitivity and specificity. The presence of toxoplasmosis can also be determined using a skin test with toxoplasmin. However, this test has also been practically not used in recent years, since there are more sensitive modern diagnostic methods that exclude the introduction of the drug into the body of the patient. In the diagnosis of intrauterine toxoplasmosis, along with NMF and TIFM, the reaction with the Sabin-Feldman dye (SFD) is used. The test is based on the inability of toxoplasmas to be stained with methylene blue in the presence of antibodies to T. gondii. This reaction is quite complex, labor-intensive and requires live toxoplasmas, which is not possible in all laboratories.
Repeated serological diagnostics of toxoplasmosis reveals specific antibodies of classes IgM and IgG to toxoplasma antigens: ELISA, RNGA and RIF (but they are not informative enough in AIDS patients): an intradermal test with toxoplasmin (native or recombinant) is performed. When analyzing and interpreting the results of serological diagnostics, it is necessary to take into account the "immunological" incubation - the appearance of antibodies to parasite antigens only after a certain latent period - and evaluate the results of studies in dynamics. The skin test indicates infection with toxoplasma, but does not provide information on the nature of the course of the disease. Pregnant women with positive serological reactions undergo an ultrasound of the fetus in dynamics.
Instrumental diagnostics of toxoplasmosis
When diagnosing cerebral toxoplasmosis (especially in AIDS patients), CT and MRI of the brain are performed: IgG titers (less often IgM) are determined in the blood serum and cerebrospinal fluid, the pathogen's DNA is detected using PCR, and the pathogen is isolated from them.
Differential diagnosis of toxoplasmosis
Toxoplasmosis is differentiated from many infectious and non-infectious diseases: lymphogranulomatosis, lymphocytic leukemia and other blood system pathologies, tuberculosis, listeriosis, yersiniosis, infectious mononucleosis. diseases of the nervous system and organs of vision. In children, taking into account age, differential diagnostics of toxoplasmosis is carried out with CMV, herpes infections and various acute respiratory viral infections, rubella, viral hepatitis. In case of repeated miscarriages, birth of children with developmental anomalies in seropositive women, it is necessary to exclude obstetric and gynecological pathology.