A 49-year-old woman with chronic HIV was recently screened for sexually transmitted infections. Syphilis testing showed a positive treponemal enzyme immunoassay (EIA) and a rapid plasma reagin (RPR) titer of 1:128. The syphilis EIA result was negative on a screening test 8 months prior. She is asymptomatic and has a normal physical examination, including no genital lesions, no evidence of rash, and no abnormal neurologic findings.