A 30-year-old woman from Nigeria presents with multiple painless papules on her vulva. She also has bilateral inguinal lymphadenopathy. She is in a po...

Question

A 30-year-old woman from Nigeria presents with multiple painless papules on her vulva. She also has bilateral inguinal lymphadenopathy. She is in a polygamous relationship. Darkfield microscopy of the lesions shows spirochaetes. RPR is positive at 1:128. TPHA is positive. She is from a region where yaws was previously endemic. How can syphilis be distinguished from yaws serologically?

Accepted Answer

Standard serological tests (RPR, TPHA, FTA-Abs) CANNOT distinguish syphilis from yaws, pinta, or bejel - all treponematoses produce cross-reactive antibodies; distinction relies on clinical features, epidemiology, and anatomical site

Answer

RPR is positive in syphilis but negative in yaws

Answer

TPHA is positive in syphilis but negative in yaws

Answer

PCR can always distinguish the subspecies

Answer

There is a specific yaws-only test available

uk-dtmh MCQ (SBA): Treponematoses Serological Indistinguishability