A Sabin–Feldman dye test is a serologic test to diagnose for toxoplasmosis. Patient serum is treated with Toxoplasma trophozoites and complement, and then incubated. After incubation, methylene blue is added. 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 dilution of the test serum at which 50% of the tachyzoites are thin, distorted and colorless is reported as antibody titer of the test serum. The test is highly sensitive and specific with no false positives reported so far.[clarification needed]
| Sabin–Feldman dye test | |
|---|---|
| Purpose | diagnose for toxoplasmosis. |
Drawbacks of this test: 1. Difficulty in maintaining the live tachyzoites. 2. 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]
References
edit- Mosby's Medical, Nursing, & Allied Health Dictionary. Edition 5, 1998 p7B4A.
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