Measurement of the amount of anti-toxoplasma antibodies in a specified sample of serum, the clear liquid that separates from blood after it has clotted completely, i.e. blood plasma from which fibrinogen has been removed. An anti-toxoplasma antibody is an immunoglobulin molecule possessing a specific amino acid sequence that binds to a specific antigen found on or in the parasite toxoplasma, a genus of sporozoa the only species of which is Toxoplasma gondii that are intracellular parasites of many organs and tissues of birds and mammals, including humans. A parasite is an organism that grows, feeds, and is sheltered on or in a different organism while contributing nothing to the survival of its host and possibly causing damage to that host. An antigen is a substance introduced into an organism which initiates an immune response, including the production of the very antibodies which bind to it in an effort to destroy it.