Syphilis is identified by its stages. There are three major stages, with a potentially long period of latency between the second and third stage. Some people with syphilis may experience one stage but never progress to subsequent stages of the disease.

The progression of a syphilis infection may include:

• Primary syphilis. The first phase of syphilis usually appears as one chancre (sore) at the site that was in contact with an infected partner. The chancre can appear between 10 and 90 days after contact, although the usual time is about 21 days. Syphilis chancres usually heal within three to six weeks, even if untreated (although the person remains infected). The disease can be transmitted from any contact with the chancre. This sore or ulcer is characterized as nonpainful, unlike ulcers associated with other types of diseases.
  
  
• Secondary syphilis. Without adequate treatment, primary syphilis progresses to secondary syphilis. Symptoms are reversible with treatment at this stage. Secondary syphilis may occur from six weeks to six months after the primary infection, sometimes while the original chancre is still present. Secondary syphilis includes numerous symptoms, many of which mimic other diseases. Not all patients with primary syphilis progress to the secondary stage. In addition, not all patients with secondary syphilis can recall a primary infection, and they may not have noticed any symptoms. As with primary syphilis, the symptoms in this stage usually resolve without treatment, often within six weeks. However, the infection may be widespread at this point. Physical contact between an infected area and other broken skin or membranes in the body can spread the disease.
  
  
• Latent stage. After the secondary stage, the patient may have brief relapses of symptoms and then syphilis may retreat for years or decades. Some people experience no further symptoms. Unless treated, the patient remains infected and can still transmit the disease in the early part of the latent period, within one year from the time of initial infection. More than two years after the start of the latent phase, patients may have no symptoms and are often not infectious.
  
  
• Tertiary syphilis. Symptoms of tertiary syphilis may develop years or decades after initial infection. At this advanced stage, the syphilis bacteria have spread throughout the body, and frequently involve the skin, cardiovascular system or central nervous system. The infection can still be treated, but damage to organs cannot be reversed. At this stage, syphilis can lead to death. Syphilis cannot be transmitted during the tertiary stage.

Congenital syphilis occurs when babies contract syphilis from their mother either through the placenta or when passing through the vagina at birth. Untreated syphilis during pregnancy results in stillbirth or death of the infant in 40 percent of the cases, according to the Centers for Disease Control and Prevention (CDC). The CDC also reports that women who acquired syphilis and were untreated in the four years preceding pregnancy passed it on to their baby in 70 percent of the cases. Infants of pregnant women adequately treated with penicillin during pregnancy have a minimal risk of developing congenital syphilis. All pregnant women who receive prenatal care in the United States are screened for syphilis.