Long-term studies of results of penicillin therapy in early syphilis.

In 1945, the US Public Health Service and co-operating treatment centres began a study of the results of penicillin therapy in a group of syphilis patients selected for intensive post-treatment observation. One objective was to test the hypothesis that patients lapsing from follow-up have the same experience as those remaining under observation, and evidence is presented which indicates that this is the case. The major objective was to evaluate the long-term results of penicillin in early syphilis. At the sixth year following penicillin treatment, satisfactory results were recorded for 98%-99% of the patients with primary and secondary syphilis (including those re-treated). There is no evidence that the cure of syphilis is enhanced by the addition of arsenic and bismuth. Seronegativity rates at the sixth post-treatment year were 81.0% for patients given combined penicillin-arsenic-bismuth therapy, and 80.7% for those treated with penicillin alone, while re-treatment rates were 17.4% and 16.3%, respectively. When cases treated with "adequate" dosage of arsenic and bismuth are analysed by the same statistical method as that employed in evaluating penicillin, the superiority of penicillin is clearly evident. A minimum of 4,800,000 units of penicillin is recommended for the treatment of early infectious syphilis.