Limitations

Prozone reactions occur in patients with secondary syphilis. False negative non-treponemal test results, arising from prozone, are also seen in incubating primary and in late syphilis. The nonreactive pattern is slightly granular or “rough” with specimens exhibiting prozone. When this pattern is exhibited, a dilution of the specimen should be prepared. Titer the diluted specimen until endpoint is reached or until no reactivity is observed. All tests exhibiting a rough appearance should be further evaluated.

 Biological false positive reactions occur occasionally with the Carbon Antigen. Such reactions sometimes occur in samples from individuals with a history of drug abuse, or with diseases such a lupus erythematosus, malaria, vaccinia, mononucleosis, leprosy, viral pneumonia and after smallpox vaccinations.

Pinta, yaws, bejel and other treponemal diseases produce positive reactions in this test.

Contaminated, lipemic or grossly hemolyzed sera should not be used because of the possibility of nonspecific reactions. A specimen is too hemolyzed for testing when printed matter cannot be read through it.