Latent syphilis
Latent syphilis is defined as having serologic proof of infection without signs or symptoms of disease. Latent syphilis is further described as either early or late. Early latent syphilis is defined as having syphilis for two years or less from the time of initial infection without signs or symptoms of disease. Late latent syphilis is infection for greater than two years but without clinical evidence of disease. The distinction is important for both therapy and risk for transmission. In the real world, the timing of infection is often not known and should be presumed to be late for the purpose of therapy. Early latent syphilis may be treated with a single intramuscular injection of a long-acting penicillin. Late latent syphilis requires three weekly injections. For infectiousness late latent syphilis is not considered as contagious as early latent syphilis. Fifty percent of those infected with latent syphilis will progress into late stage (tertiary) syphilis, 25% will stay in the latent stage, and 25% will make a full recovery.