Most commonly used treponemal test in diagnosis of syphilis is:

TPHA is just as specific as FTA-ABS and almost as sensitive, except in the primary stage. It is also much simpler and more economical. No special equipment is needed. Kits are available commercially. These advantages have made TPHA a standard confirmatory test. TPHA titres may fall rapidly following treatment in secondary syphilis, but remain positive for life in low titres. Key Point: TPHA being simpler, reliable and easier to use is more routinely involved serological test for syphilis. Ananthanarayan R. Ananthanarayan and Paniker's textbook of microbiology.Edition 6. Page 383