Patient serum is treated with Toxoplasma trophozoites and complement, and then incubated.
If anti-Toxo antibodies are present in the serum, the antibody-antigen complex activates complement to lyse the parasite membrane, Toxoplasma trophozoites are not stained (positive result); if there are no antibodies, trophozoites with intact membrane are stained and appear blue under microscope (negative result).
The test is highly sensitive and specific with no false positives reported so far.
It detects immunoglobulin G(IgG) antibodies, hence cannot differentiate between recent or past infection.
3.False positive for Sarcocystis, Trypanosoma lewisi, Trichomonas vaginalis[clarification needed]