Toxoplasma gondii (T. gondii) is the name of a single-celled parasite, which causes a disease known as toxoplasmosis. T. gondii infects a large proportion of the worlds population but uncommonly causes clinically significant disease, except in individuals at risk of severe complications, which include fetuses (pregnant females), newborns, and immunologically impaired patients - those with hematologic malignancies, bone marrow and solid organ transplants, or AIDS.
Amniocentesis may be done at 20-24 weeks gestation if congenital disease is suspected. A CT scan of the head may be done if cerebral toxoplasmosis is suspected.
The laboratory diagnosis of toxoplasmosis may be documented by:
1. Serologic testing (looking for IgG or IgM antibodies in blood) is the routine method of diagnosis. The results of a double-sandwich IgM enzyme-linked immunosorbent assay (ELISA) are more sensitive and specific. The results of the IgG avidity test may help discriminate those with acute infection from those with chronic infections better than other assays.
2. Demonstration of parasites in patient specimens - blood, body fluids or tissue.
3. Detection of T. gondii antigen in blood or body fluids by ELISA technique indicates acute infection.
4. Polymerase chain reaction (PCR) may be useful in the diagnosis, especially in detecting congenital infections in utero.