What is Latent Syphilis?

Latent syphilis occurs after the primary and secondary stages of the disease and is normally asymptomatic. During this stage, the telltale symptoms associated with primary and secondary syphilis have resolved, but the patient is still seroreactive. Patients with this stage of syphilis may remain without symptoms, develop the symptoms of secondary syphilis again, or progress to tertiary syphilis.

Syphilis is caused by the bacteria Treponema pallidum and is most commonly spread by sexual contact with an infected person who has sores at the time of contact. The sores are not always visible as they may occur within the genitals. Other, less common modes of transmission are from mother to fetus in utero, or contact with an active lesion on broken skin or mucous membrane, such as while kissing. Latent syphilis is not transmitted as such, but occurs after the first two stages of the disease.

Once infected, the disease remains quiet for an incubation period of between three and six weeks. Primary syphilis develops at this point, with a small sore at the place where the bacteria entered the body. The sore is referred to as a chancre and is often not noticed, due to its painless nature. It may be hidden within the genitals and disappears after about six weeks. At this stage it is highly contagious.

Within four to 10 weeks of the appearance of the chancre, secondary syphilis will develop. The symptoms of the secondary stage may include fever, malaise, muscle and joint pains, lymphadenopathy or swollen lymph nodes and a rash. With such a wide range of symptoms it is not surprising that syphilis is often referred to as "the great impostor." These symptoms may resolve by themselves and return repeatedly for up to a year.

If not treated, latent syphilis results. This is a stage that is mainly asymptomatic, although skin lesions may occasionally recur. It is mostly noncontagious but transmission may occur during the early latent phase. According to the Centers for Disease Control and Prevention (CDC) classification, latent syphilis can be divided into three categories: early latent syphilis, which refers to the disease when the initial infection occurred within the previous 12 months; late latent syphilis, when initial infection was longer than 12 months ago; and latent syphilis of unknown duration, where the date of infection is unknown.

Syphilis may remain latent forever. About one third of people with the latent stage will develop tertiary syphilis. This is characterized by damage to the brain, nerves, eyes, heart, blood vessels, liver, bones or joints. Neurosyphilis may result, which is when the infection spreads to the brain, causing a range of serious central nervous system symptoms such as dementia and meningitis.

All stages of syphilis are treated with benzathine penicillin G. The dose and duration of therapy is determined by the stage of the disease. For early latent syphilis, just one dose is needed for treatment, but for late latent syphilis and latent syphilis of unknown duration, three doses at weekly intervals is necessary. Treatment is usually successful and complete, but follow-up tests need to be done by a medical practitioner to confirm this.