The pathogenesis of syphilis is characterized by a great number of components. “Cooperation” of Treponema pallidum with the body of the infected individual determines the development of syphilis.
The general health of the infected person determines the severity of infection. Furthermore, local mechanisms take part in the formation of clinical characteristics of syphilids. A syphilid is any cutaneous and mucous membrane lesion characteristic of secondary and tertiary syphilis. All of the above can explain the variety of clinical manifestations and courses of syphilis.
According to the course and clinical manifestations, there are 4 periods:
- incubation period (duration: 4–5 weeks) from the moment of contracting the infection to appearance of first clinical manifestations;
primary period (duration 6–7 weeks) characterized by appearance of “hard” chancre;
- secondary period developing 2–3 months after the moment of contracting the infection characterized by the appearance of generalized eruptions;
- tertiary period developing 3–5 years after infection characterized by the development of infectious granulomas, impairment of internal organs, the musculoskeletal and nervous system.
The spread of Treponema pallidum microorganisms in the body of the infected individual begins 2 hours after penetrating the skin surfaces. It occurs mostly through lymphogenic routes. While moving along the lymphogenic routes, their number increases due to proliferation rather than invasion of lymph nodes. The latter respond with hyperplasia of lymphoid tissue.
Primary syphilis. At the end of the incubation period, primary syphilomas or hard chancres develop at the site of invasion. The duration of primary syphilis is approximately 45–50 days. Its localization may be genital, extra-genital, peri-paragenital (anus) . As for their number, there may be single or multiple chancres. As for the size, the lesions may be dwarfish or giant. As for the depth of impairment, there may be erosive and ulcerative chancre. Atypical chancres are whitlow-like chancre, amygdalite chancre and indurative edema. The latter occur rarely, and the diagnosis is much more difficult.
Regional scleradenitis is the second important symptom of primary syphilis. It occurs 7–10 days after appearance of hard chancres. Lymph nodes enlarge up to 2–3 cm in diameter. They have dense elastic consistency.
They are not closely connected with one another, environmental tissues and skin.
They are painless. The skin above them is not changed. Typical clinical manifestations of hard chancre may change as a result of secondary infection.
Possible complications may include balanitis, balanoposthitis, phimosis, paraphimosis, gangrenization, and phagedenism.
Secondary syphilis is a stage of dissemination of the disease. It is characterized by multiplication and spread of spirochetes in the body. Treponemas are detected in the majority of organs and tissues in spite of presence of anti-treponema antibodies in high concentrations. Nonspecific symptoms of secondary syphilis develop within 6 weeks to 6 months after exposure or 1–5 weeks after the primary infection. The symptoms include fever, headache, sore throat, arthralgia, anorexia, and generalized lymphadenopathy. The most common manifestations of the secondary period of syphilis are generalized rash on the skin and mucous membranes (for example roseolar and papular rash, eroded papules in the oral cavity, condyloma lata, alopecia, and leukoderma). Rare manifestations include acute meningitis that occurs in about 2% of patients, hepatitis, renal disease, hypertrophic gastritis, patchy proctitis, ulcerative colitis, rectosigmoid mass, arthritis, periostitis, optic neuritis, interstitial keratitis, iritis and uveitis.
Symptoms of secondary syphilis may spontaneously regress but they may recur over a 1-year period after the infection occurred if the patient is not treated.
During the secondary stage of infection, all serological tests for syphilis are positive. Negative findings are quite rare. Treponema pallidum microorganisms are detectable in syphilids.
There are 4 groups of syphilids of the skin and mucosa: spotted syphilids, papular syphilids, vesicular syphilids, and pustular syphilids. Not rarely, there may be rash simultaneously composed of roseolas (rose spots) and papules; papules and pustules; papules, pustules and roseolas. Characteristic signs of secondary recurrent syphilis are alopecia and leukoderma.
Tertiary syphilis. One third of untreated patients may develop tertiary syphilis 10–20, and even 3–6 years after the initial infection. However, in some cases it can take up to 50 years. Invasion of Treponema pallidum microorganisms into the central nervous system, cardiovascular system, skin, bones, joints and internal organs result in manifestations of late syphilis. Specific formations called gummas may be single or numerous and vary in size from microscopic defects to big tumor-like lumps of inflammation known as granulomas that contain small amounts of Treponema pallidum microorganisms. The granulomas are chronic and represent the inability of the immune system to completely clear the organism. They may appear almost anywhere in the body including in the skeleton. The gummas produce a chronic inflammatory state in the body with diffuse effects on the local anatomy. During this period, patients may develop neurosyphilis, cardiovascular syphilis, impairment of internal organs and the musculoskeletal system. Tertiary syphilis as well as secondary syphilis may be recurrent and remissive. This stage of the disease is not considered to be contagious. Basic diagnosis includes positive results of Treponema reactions. Direct microscopy detects Treponema pallidum microorganisms in gummas and biopsy samples. A significant proportion of patients with syphilis have a traditional course of syphilitic infection. However, there may be differences in clinical manifestations and character of the disease course. They are associated with changes in immunological reactivity of the organism, wide and irrational administration of antibiotics, biological properties of Treponema pallidum microorganisms and other sexually transmitted infections. In case of debilitating diseases, HIV-infection, malnutrition, alcoholism, illegal drug addiction, tobacco abuse, hard physical work and other exposures that weaken the bodythe disease may take a malignant course.