THE EVALUATION of therapeutic results in late latent syphilis is a difficult problem. There are no symptoms or signs that can be influenced by treatment, and serologic reversal is an uncertain criterion of successful therapy. The effectiveness of different kinds of treatment must be judged solely by the comparative incidence of subsequent clinical manifestations of the disease. Proper evaluation of any type of therapy will thus require the prolonged observation of many patients, but because of the recent revolution in antisyphilitic therapy, with an almost total switch to penicillin, we cannot afford to wait very many years to discover whether the newer treatment methods are effective.
Today penicillin is universally used as the sole therapeutic agent in latent syphilis. Penicillin is effective in early manifest syphilis and in late benign tertiary and neurosyphilis and is therefore presumed to be useful in the intervening latent stage, but proof of