The significance of complement fixation test in clinical diagnosis of toxoplasmosis.

Background: The complement fixation test (CFT) is the basic method in the diagnosis of toxoplasmosis. Despite its standard and reproducible results, it is rarely used in routine diagnosis of toxoplasmosis where the detection of IgG by means of EIA tests is widely used.

Objective: The study is focused on the verification of CFT value within the spectrum of specific classes of immunoglobulins IgG, IgM, IgA antibodies and avidity of IgG antibodies, as well as on the clinical diagnosis of toxoplasmosis.

Method: The study analysed 1705 samples of serum from patients suspected to be infected by Toxoplasma gondii. Out of these patients 451 suffered from acute lymphadenopathic toxoplasmosis (6 with seroconversion of both CFT and IgG antibodies) and 1254 serum samples were collected from patients with latent infection, out of whom 176 were with long-term persistence of IgM, or IgA antibodies after the elimination of disease.

Conclusion: CFT is a reliable indicator of Toxoplasma infection and as opposed to IgG antibodies its levels enable a more objective determination of its course. However from the aspect of the determination of the stage of toxoplasmosis from a single sample of serum, the combination of CFT with IgM or IgA antibodies with quantitative order or test of avidity of IgG antibodies must be performed. (Tab. 4, Fig. 4, Ref. 30.).