Syphilis and HIV are prone to occur concomitantly and the two diseases share several modes of acquisition and risk factors such as men who have sex with men (MSM), sexual workers, intravenous drug users, previous history of sexual transmitted diseases (STDs), and multiple partners. HIV infection rates of up to 50% have been reported among patients diagnosed with syphilis in several regions, with higher HIV infection rates among MSM. Besides, syphilis ulcers are proposed to enhance the transmission of HIV. In Taiwan, there is also an increasing prevalence of syphilis and HIV co-infection among MSM. Therefore, to treat syphilis is an important issue for public health.
According to literature review, whether patients with HIV and syphilis co-infection had higher serologic failure rate remains controversial, especially in the era after highly active anti-retroviral therapy (HAART) was introduced since 1996. Ghanem et al recently demonstrated that the use of HAART may reduce syphilis failure rates among HIV-infected patients who have syphilis. In addition, the treatment guideline in 2006 suggested that the treatment of primary syphilis and secondary syphilis is single dose benzathine penicillin G regardless of HIV status; however, it goes on to suggest that "some specialists recommended additional treatments for HIV-infected patients", namely 3 doses, each a week apart. There is no reference and evidence of strength of the suggestion but only specialists' opinion.
In the study, we aim to compare serologic response of syphilis to penicillin treatment between HIV-infected and HIV-uninfected patients and to compare serologic response of early syphilis (primary or secondary) to 1 dose and 3 doses of benzathine penicillin G among HIV-infected patients. A longitudinal follow-up of serologic response will be conducted after syphilis treatment.