Characteristics: . Slender spiral, microaerophilic gram-negative rods. . Not cultured in artificial media, in fertilized eggs and tissue culture, but the saprophytic Reiter strain grows in anaerobic culture . Actively motile, rotating steadily around their endoflagella . Remain viable in the blood or plasma store at 4 0c at least for 24 hrs (transmitted via blood transfusion) Antigenic structure: . Membrane proteins . Outer sheath proteins . Endoflagellar core proteins . Cardiolipin . Hyaluronidase
Pathogenesis and Clinical features: Natural infection with T. pallidum is limited to the human host
Incubation period is 3-4 weeks. Route of transmission is sexual contact.
It has four stages.
Primary stage: Hard chancre: Clean-based, non-tender,
indurated genital lymphadenopathy.
Secondary stage: Manifests with generalized maculopapular rash condylomata lata and white patches