As stated in the introduction of this text, syphilis is caused by a bacterium called Treponema pallidum. Transmission occurs in the vast majority of cases, by sexual contact and happens by the penetration of bacteria through microscopic wounds or abrasions in the mucosa of the vagina or penis. It is estimated that the risk of contagion in each unprotected sexual intercourse with an infected partner is approximately 30%. If there are wounds or sores in the vagina / penis, this risk is even greater. Patients transmitting syphilis are those with the illness during primary or secondary stages, especially if there are active lesions in the sexual organs. Although not 100% effective, the condom is still the best method for preventing sexual transmission of syphilis.
In advanced stages of disease, syphilis can be transmitted by kissing and even by touch if there are lesions on the skin or mouth (the symptoms explained below).
The transmission of syphilis by blood transfusion is very rare as Treponema pallidum does not survive more than 48 hours in stored blood.
There is also congenital syphilis that is acquired by the fetus when the mother is infected by Treponema pallidum during pregnancy. Syphilis in pregnant women can cause miscarriage, premature birth, fetal death and malformations.
The disease is divided into three stages, called primary syphilis, secondary syphilis and tertiary syphilis.
Symptoms of primary syphilis
The incubation period, i.e. the time between infection and the onset, lasts on average for 2-3 weeks. However, there are cases where this interval may be as short as three days or as long as three months.
The lesion of primary syphilis is a papule (a small, raised, solid pimple or swelling on the skin) on the genitals; in a few hours it turns into a painless ulcer. In women, this injury may go unnoticed, since it is small (on average 1 cm in diameter), painless and usually stay hidden among the pubic hair or inside the vagina. No other symptoms associated with lesions of primary syphilis, the patient has a maximum increase in the groin lymph nodes (buboes).
In some cases ulcer can arise in the mouth or pharynx, if the transmission has been given via the oral sex.
The ulcer of syphilis is called chancre, and after 3 to 6 weeks it disappears even without treatment, leading to a false impression of a spontaneous cure. Thus, syphilis is a disease initially painless, it often tends to go unnoticed and seems to disappear spontaneously after some time. The problem is that the disappearance of the chancre does not mean healing , however, the bacterium is now multiplied and silently spreads body.
Symptoms of secondary syphilis
Some weeks or months after the disappearance of the chancre, syphilis returns, now spread throughout the body. This form of syphilis is manifested by rash, classically on the palms and soles. Also common are fever, malaise, loss of appetite, joint pain, hair loss, eye lesions and enlarged lymph nodes diffusely throughout the body.
The lesions on the soles of the feet, palms and oral mucosa are characteristic, but the skin eruptions can occur anywhere on the body.
Another typical lesion of secondary syphilis is called condylomalata, a wet lesion, resembling a large wart, which usually appears near where there was injury to the chancre in primary syphilis.
There are cases, however, that secondary syphilis presents few symptoms, so that the patient does not give much importance to the frame. About 20% of patients with secondary syphilis do not consider their symptoms bothersome enough to seek medical help.
Just as occurs in primary syphilis, the symptoms of secondary syphilis resolve spontaneously without treatment.
Symptoms of tertiary syphilis
Patients may be one to several years, even decades, asymptomatic before a new recurrence. The tertiary form is the most serious. Tertiary syphilis presents three types of events:
Goma syphilitic large ulcerated lesions that can affect the skin, bones and internal organs
Cardiovascular syphilis can involve the aorta, causing aneurysms and aortic valve lesions
Neurosyphilis affects the nervous system, washing with dementia, meningitis, stroke and motor problems in spinal cord and nerve
In primary syphilis, the chancre appears when as yet there was time for the body to produce antibodies to Treponema pallidum, so blood tests are usually negative at this stage. Laboratory confirmation can be made after collecting material from the ulcer for direct visualization of the bacteria under a microscope. This test is not always necessary, since the genital ulcers of syphilis are well characterized. Your doctor will usually start treatment based only on clinical data, waiting a week or two to confirm the laboratory diagnosis.
The diagnosis of secondary syphilis, tertiary, or primary, as in later phases, is done by two serological tests: VDRL and FTA-ABS (or TPHA).
The VDRL test is the simplest and screening is used. The result is given in forms of dilution, i.e., a result 1/8 means that the antibody was identified to 8 dilutions, a result of 1/64 shows that antibodies can be detected even after we dilute the blood 64 times. The greater the dilution that still detects antibody, the more positive is the result.
If the above explanation only confused you just know that the VDRL = 1/2 is a title lower than 1/4, which is lower than 1/8 and so on. The higher is the title, the more positive is the examination.
As the VDRL may be positive in several diseases other than syphilis, such as lupus, liver disease, mononucleosis, leprosy, smallpox, rheumatoid arthritis, etc. we consider only values greater than 1/32 as reliable for diagnosis. VDRL may also have false positive in the elderly.
VDRL usually becomes positive between 4 and 6 weeks after contamination. Generally their values begin to rise one to two weeks after the appearance of the chancre. So if the test is done one or two days after the appearance of the lesion of syphilis, the VDRL test can give false negative.
FTA-ABS test or TPHA
The FTA-ABS test is more specific and sensitive than the VDRL. Your window period is shorter, and may be positive already after a few days after the appearance of the chancre. The FTA-ABS or TPHA also has lower rates of false positive VDRL.
Once positive, FTA-ABS will remain so for the rest of its life, even after cure. The values of the VDRL after curing fall progressively, becoming negative after some years. VDRL is usually used for disease screening and FTA-ABS for confirmation.
Note: The FTA-ABS is a bit higher than the TPHA, presenting a higher sensitivity.
Finally, we end with the following situations:
Positive VDRL and positive FTA-ABS (or TPHA) test confirms the diagnosis of syphilis
Positive VDRL and negative FTA-ABS (or TPHA) indicate that there is other disease, not syphilis
Negative VDRL and positive FTA-ABS (or TPHA) test indicate very early stage syphilis or healed syphilis or syphilis in the tertiary stage
Negative VDRL and negative FTA-ABS (or TPHA) dismiss the diagnosis of syphilis (there are rare cases where the test is done too early, there may be false negative on both tests)
Syphilis is curable if treated properly. The treatment of syphilis is different depending on the stage of the disease stage:
Primary or secondary syphilis is treated with benzathine penicillin 2.4 million units in a single dose
Syphilis of more than 1 year of evolution or indefinite is treated with benzathine penicillin 2.4 million units in three doses, with one week interval between each
Penicillin allergic patients can be treated with doxycycline (100mg 2x, daily for 14 days) or azithromycin (2 g, a single dose), but they are not as effective as penicillin.
In some cases, such as contaminated with syphilis in pregnant women, may be given a treatment for allergy desensitization of the patient so that it can be treated with penicillin. The preference is always for treatment with penicillin.
After the start of treatment the lesions begin to disappear within the first days. However, to confirm the cure a person must repeat the blood tests.
Every patient treated for syphilis should redo the VDRL at 6 and 12 months. The criterion of cure of syphilis is the disappearance of symptoms and a fall of 4 degrees in antibody levels. Examples:
VDRL was 1/64 and after treatment fell to 1/16
VDRL was 1/32 and after treatment fell to 1/8
VDRL was 1/128 and after treatment fell to 1/32
The more time passes, the more titles fall, and may even become negative after a few years (there are cured patients that remain a lifetime with low titers of VDRL as 1/2 or 1/4). But negative VDRL doesn't attest to the cure of syphilis.
Titles in primary syphilis fall faster than in secondary and tertiary syphilis. The FTA-ABS does not mean to control treatment, because, as already explained, it is not negative after cure. Once positive, FTA-ABS will remain so for the rest of its life. It is what we call an immunological scar.