title: Letter: Dark-field examination in early primary syphilis.
mesh_terms: D005455:Fluorescent Antibody Technique; D006801:Humans; D008297:Male; D013587:Syphilis / Q000175:diagnosis*; D013588:Syphilis Serodiagnosis; D013997:Time Factors; D014210:Treponema pallidum / Q000276:immunology / Q000302:isolation & purification