Syphilis is a complex sexually transmitted infection caused by the bacterium Treponema pallidum. If untreated, it progresses through stages over many years, earning it the nickname “the great imitator” because its symptoms resemble many other diseases. While early stages involve external signs like sores and rashes, the infection can become chronic and persist silently. The late stage, also known as tertiary syphilis, is a severe, destructive internal disease that can lead to permanent disability and death.
Progression to the Late Stage
The progression to late syphilis follows the initial, highly infectious phases. The primary stage involves a single, often painless sore (chancre) that heals spontaneously within three to six weeks. This is followed by the secondary stage, which typically presents as a systemic rash, sometimes involving the palms and soles, along with flu-like symptoms. These symptoms resolve on their own, regardless of treatment.
After secondary symptoms disappear, the infection enters the latent stage, an asymptomatic period where the bacteria remain in the body without visible signs. Latent syphilis is categorized as early (less than one year after infection) or late (more than one year after infection). Late latent syphilis is generally not considered sexually transmissible because the spirochetes are less active.
The late or tertiary stage develops in approximately 15% to 40% of untreated individuals, typically 10 to 30 years after the initial infection. During this chronic phase, the bacteria cause severe, slow-developing damage to internal organs. The individual is no longer infectious, but the spirochetes trigger an intense inflammatory response that destroys tissues throughout the body.
Severe Organ Damage in Late Syphilis
The destructive effects of late syphilis are categorized into three main forms affecting different organ systems.
Neurosyphilis
The central nervous system is a common target, leading to neurosyphilis, which is particularly damaging in the late phase. Late symptomatic neurosyphilis can manifest as general paresis, a slow degenerative process of the brain causing dementia, personality changes, and psychosis. Another form, tabes dorsalis, results from the deterioration of the spinal cord’s posterior columns. This leads to a loss of coordination, sharp, stabbing pains in the limbs, and impaired positional sensation.
Cardiovascular Syphilis
Cardiovascular syphilis is a late-stage complication, usually appearing 10 to 30 years after the original infection. The bacteria primarily attack the vasa vasorum, the small blood vessels supplying the aorta wall, causing syphilitic aortitis. This inflammation weakens the aortic wall, potentially leading to an aortic aneurysm, a bulge that risks rupture. Damage to the aortic valve is also common, resulting in aortic regurgitation, where the valve fails to close properly, stressing the heart and causing heart failure.
Gummatous Syphilis
The third manifestation is gummatous syphilis, characterized by the formation of soft, tumor-like inflammatory lesions called gummas. Gummas are localized areas of chronic inflammation and necrosis (tissue death) found on the skin, bones, or internal organs, most often the liver. While not cancerous, these growths cause localized tissue destruction and organ dysfunction. Gummatous syphilis can be debilitating, depending on the lesion’s site.
Identifying and Treating Late Syphilis
Diagnosis relies on patient history and specific blood tests. The standard approach involves initial screening with a non-treponemal test (such as VDRL or RPR), followed by confirmation with a treponemal test. In late disease, non-treponemal test titers may be low or non-reactive due to low bacterial activity, making the confirmatory treponemal test necessary. A comprehensive evaluation for neurosyphilis is also performed if the patient exhibits any neurological, visual, or auditory symptoms.
To confirm neurosyphilis, a lumbar puncture (spinal tap) is often required to analyze the cerebrospinal fluid (CSF). Abnormal CSF findings dictate a more aggressive treatment regimen, as the antibiotic must effectively penetrate the central nervous system. Penicillin remains the preferred antibiotic for treating syphilis at all stages due to the bacteria’s continued sensitivity.
Treatment for late syphilis requires a longer course than for the early stages. The standard regimen involves administering Benzathine Penicillin G (2.4 million units) via intramuscular injection once a week for three consecutive weeks. This prolonged course ensures the drug reaches established bacterial populations deep within the tissues. Individuals with confirmed neurosyphilis require intravenous aqueous penicillin G for 10 to 14 days to achieve the higher drug concentrations needed to clear the infection from the central nervous system. Following treatment, patients undergo regular blood tests to monitor the decline of non-treponemal test titers, confirming eradication.