Serological diagnosis of syphilis. PHLS Syphilis Serology Working Group

The availability of an increasing number of enzyme immunoassays (EIAs) for detecting syphilis antibodies makes it appropriate to review approaches to syphilis serology and to assess the role of syphilis EIAs in routine diagnostic microbiology laboratories. This paper summarises the principles and practice of syphilis serology and provides recommendations on the use of laboratory tests for syphilis in UK diagnostic microbiology laboratories. The main recommendations are summarised in a testing algorithm. Treponemal EIAs are an appropriate alternative to the use of combined Venereal Disease Research Laboratories/rapid plasma reagin and Treponema pallidum haemagglutination assay (TPHA) tests for screening for syphilis. If a treponemal EIA is used for screening an alternative treponemal test, such as TPHA, should be used for confirmatory testing. The fluorescent treponemal antibody-absorbed test is probably best reserved for specimens giving discrepant results. Such specimens may be referred to the PHLS laboratories that provide confirmatory treponemal testing for reference testing and to facilitate collection of surveillance data on what remains an important public health problem.