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  • STI caused by the spirochete Treponema pallidum
  • Sexually transmitted: direct contact required
  • Cannot be cultured on artificial media or cell culture
  • Fragile in the environment
  • Very thin spirochete that it is not seen except in darkfield microscopy or silver staining
  • Stages of disease:
    • Primary--chancre
    • Secondary--rash and mucous membranes
    • Latent--no symptoms
    • Late or tertiary--neurosyphilis, cardiac or gummatous lesions
      Public Health Image Library (PHIL) at CDC/CDC/Bill Schwartz