Spirochete (Treponema pallidum) is the causative agent of syphilis. Spirochete can now be successfully localized with a treponema pallidum antibody using immunohistochemical techniques in formalin-fixed, paraffin-embedded (FFPE) tissue. In the past, localization of the spirochete agent was achieved with silver stains such as Steiner’s and/or Warthin-Starry. The spirochete antibody consists of a rabbit purified IgG fraction that is highly specific. Treponema pallidum antibody also cross-reacts with burgdorferi (Lyme disease).