Tests for Syphilis Are Convenient and Reliable

Two new convenient tests, used in combination, provide reliable diagnosis of syphilis infection.

The causative organism of syphilis is Treponema pallidum, a spirochete which cannot be grown on culture media or in tissue culture. The infection is normally diagnosed by the detection of antibody specific for T pallidum in the patient's blood or cerebrospinal fluid (CSF). Detection of the antibody becomes possible three to four weeks after infection. Two groups of antibodies are formed in response to infection: reagin antibodies that are present in active disease, and specific T pallidum antibodies, which persist long after the infection has been successfully treated.

The Oxoid (Basingstoke, UK) diagnostic reagent venereal diseases research laboratory (VDRL) carbon antigen test is a rapid agglutination test that detects reagin antibodies in serum or plasma in just eight minutes. The Oxoid T pallidum hemagglutination assay (TPHA) test is a sensitive passive hemagglutination test that detects specific T pallidum antibodies in serum within one hour. Used in combination, these assays provide laboratories with inexpensive, easy-to-perform, and rapid tools for the diagnosis of syphilis. No specialized equipment is required and results are clearly visible and easily interpreted.

According to the Health Protection Agency in London (HPA, UK), the number of sexually transmitted infections in the UK has continued to increase, rising by 3% from 2004-2005. The biggest increase was seen in the number of new cases of syphilis, which rose by 23% to 2,807 cases in 2005. Therefore, laboratories need accurate and reliable diagnostic methods that are easily accessible and cost effective.

Sexual infection diagnoses have been almost continually rising since the 1990s, with the highest increases in recent years occurring in the 16-24 age group. Professor Peter Borriello, director of the HPA's center for infections, said that the figures contained "mixed news” with the fall in gonorrhea showing that real progress was being made. "However, it is disappointing to see that there was a further rise in new diagnoses of sexually transmitted diseases (STIs) and these figures show there is still much to be done to tackle the continuing spread of infection.” He added that some of the rise could be accounted for by the better testing arrangements that have been introduced by sexual health clinics.



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