The purpose of this study is to observe the serological response to 1 or 3 weekly doses of benzathine penicillin G in patients with early syphilis.

Inclusion Criteria:

1. Persons with confirmed early symptomatic syphilis (primary or secondary) or high-titer latent syphilis
2. A rapid plasma reagin (RPR) test was positive, with a titer were 1:4 or higher. In addition, Treponema pallidum particle agglutination assay and/or fluorescent treponemal antibody absorption test were reactive.

Exclusion Criteria:

1.Patients who were pregnancy, known allergy to penicillin, use of antibiotics active against syphilis during the preceding six months for symptomatic cases or during the preceding two years for asymptomatic cases, and concurrent illnesses requiring treatment with antibiotics effective against syphilis. 2. if RPR titers were found to be 1:4 or less or the T. pallidum particle agglutination test was nonreactive, participants were retrospectively excluded from the trial unless primary syphilis was confirmed by the finding of T. pallidum in ulcer exudates on direct immunofluorescence

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