Syphilis is a systemic disease caused by Treponema pallidum. On the basis of clinical findings, the disease has been divided into stages, which are used to help guide treatment and follow-up. Persons who have syphilis might seek treatment for signs or symptoms of primary syphilis infection (i.e., ulcers or chancre at the infection site), secondary syphilis (i.e., manifestations that include, but are not limited to, skin rash, mucocutaneous lesions, and lymphadenopathy), or tertiary syphilis (i.e., cardiac or gummatous lesions). Latent infections (i.e., those lacking clinical manifestations) are detected by serologic testing. Latent syphilis acquired within the preceding year is referred to as early latent syphilis; all other cases of latent syphilis are late latent syphilis. Neurosyphilis is a site of infection and can occur at any stage of syphilis. Early neurologic clinical manifestations (i.e., cranial nerve dysfunction, meningitis, stroke, acute altered mental status, and auditory or ophthalmic abnormalities,), are usually present within first few months or years of infection. Late neurologic manifestations (i.e., tertiary syphilis) occur 10-30 years after infection. Treatment for late latent syphilis, latent syph of unknown duration and tertiary syphilis require a longer duration of therapy because organisms might be dividing more slowly; however, the validity of this concept has not been assessed.