Detection of IgG antibodies to Toxoplasma gondii, the causative agent of toxoplasmosis, by ELISA.Toxoplasma gondii IgG (ELISA) is the default test for all Toxoplasma gondii testing. Should the ELISA yield a positive result, an IFA will be performed at no additional cost to the client 1:64, 1:128, 1:256, 1:512, 1:1024, and 1:2048 dilutions.