What is syphilis?
Syphilis is an infectious-contagious disease transmitted mainly through the sexual path. The causative agent is the bacterium Treponema pallidum , whose most common symptom is a painless ulcer in the genital region.
When not properly treated, syphilis develops as a three-stage disease: primary, secondary, and tertiary syphilis. Each stage has different symptoms and in later stages, the disease can spread throughout the body, causing serious damage to internal organs such as the heart and brain, and deforming lesions on the skin.
In the pre-antibiotic era, syphilis was a chronic, prolonged, painful and deforming disease, being extremely feared and highly stigmatized. Currently, however, it is an easily treated disease with antibiotics and a high cure rate. The vast majority of cases are diagnosed in stages 1 or 2 and patients can heal without major sequelae.
Forms of transmission
The transmission of T. pallidum occurs in the vast majority of cases through the sexual route and is due to the penetration of the bacterium through microscopic wounds or abrasions in the mucosa of the vagina or the penis.
It is estimated that the risk of infection in each unprotected sex with an infected partner is approximately 30%. If there are wounds or inflammations in the vagina / penis, this risk is even higher.
The patients who transmit T. pallidum are those that present the disease in the primary or secondary phase, especially if there are active lesions in the sexual organs. Although not 100% effective, condoms arestill the best method to prevent sexually transmitted infections.
In later stages of the disease, the bacteria can be transmitted by kissing and even touching the skin or mouth if there are active lesions, as will be explained later.
Currently, transmission of syphilis by blood transfusion is very rare, since Treponema pallidum does not survive for more than 48 hours under current conditions that blood banks store blood.
There is also congenital syphilis, which is acquired by the fetus when the mother is contaminated by Treponema pallidum during pregnancy. The infection in the pregnant woman can cause abortion, premature birth, malformations and fetal death. In this article, we will specifically talk about syphilis in adults.
Signals and symptons
As already mentioned, Treponema pallidum infection is divided into three stages, termed primary, secondary and tertiary syphilis.
Symptoms of primary syphilis
The incubation period, that is, the time interval between the contagion and the first symptoms, is in average of 2 to 3 weeks. However, there are cases where this interval can be as short as three days or as long as three months.
The lesion of primary syphilis is a papule (a small rise in the skin) in the genitals, which in a few hours turns into a non-painful ulcer. In women, this lesion may go unnoticed, as it is small (on average 1 cm in diameter), painless and is usually hidden between the pubic hairs or inside the vagina.
The syphilis ulcer is called hard cancer. After 3 to 6 weeks, the lesion disappears even without treatment, leading to the false impression of spontaneous healing. There are no other symptoms associated with the primary lesion. In addition to cancer, the patient may have at most an enlargement of the groin (inguinal) lymph nodes.
In some cases, the ulcer may appear in the mouth or pharynx if transmission has occurred through oral sex.
Therefore, syphilis is initially a painless disease, which often goes unrecognized and disappears spontaneously after some time. That is the big problem. Any treatment, ineffective as it may be, may appear to be effective, because the cancer will disappear in one way or another. This disappearance, however, does not mean cure, on the contrary, the bacteria may be multiplying and spreading through the organism silently.
Symptoms of secondary syphilis
In 25% of untreated patients in the primary phase, syphilis returns after a few weeks or months. But now, the disease is widespread throughout the body. In some cases, the patient only discovers that he is infected in the secondary phase, because the primary lesion may have gone unnoticed at the time.
Secondary syphilis manifests with rashes on the skin, classically on the palms of the hands and soles of the feet. Also common symptoms are: fever, malaise, loss of appetite, joint pain, hair loss, eye lesions and enlargement of the lymph nodes diffusely through the body.
Presentation with lesions on the soles of the feet, palms and oral mucosa is the most characteristic form, but skin eruptions can occur anywhere in the body.
Another typical lesion of secondary syphilis is the so-called condylomata , a humid, wart-like lesion that usually appears near the site of the hard cancer lesion in the primary phase.
There are cases, however, in which secondary syphilis presents few symptoms, so that the patient does not give much importance to the condition. About 20% of patients in the secondary stage do not find their symptoms uncomfortable enough to seek medical help.
As in the primary phase, the symptoms of secondary syphilis disappear spontaneously without any treatment.
Latent stage of syphilis
After the lesions disappear in the secondary phase, the patient enters the latent phase of the disease. There are no symptoms, but laboratory tests for syphilis are positive (I'll explain later). The latent phase is divided into early latent, when the contamination by Treponema pallidum occurred less than 1 year, or late latent, in cases of infection for more than one year.
Symptoms of tertiary syphilis
Patients may remain asymptomatic for several years, even decades, in the latent phase before a new return of the disease. This new phase, when the symptoms return, is tertiary syphilis, the most severe form of the disease.
The tertiary phase presents three types of manifestations:
Syphilitic gum: Large ulcerated lesions that can attack skin, bones and internal organs.
Cardiovascular syphilis: involvement of the aortic artery, causing aneurysms and aortic valve lesions (read: What is an aneurysm? ).
Neurosyphilis: affects the nervous system, washing to dementia, meningitis , stroke and motor problems due to injury to the spinal cord and nerves.
In primary syphilis, when hard cancer appears, there has not yet been time for the body to produce antibodies against Treponema pallidum , so blood tests are usually negative at this stage.
Laboratory confirmation can be made after collection of ulcer material for direct visualization of the bacteria under a microscope. This test is not always necessary, since genital ulcer is very characteristic. Usually, the doctor starts treatment based only on clinical data, waiting one or two weeks to confirm the diagnosis in the laboratory.
The diagnosis of syphilis is usually made through two serological tests: VDRL (or RPR) and FTA-ABS (or TPHA).
Non-treponemal tests - VDRL and RPR
VDRL and RPR are called nontreponemal tests, as they screen for antibodies not against the bacterium Treponema pallidum itself, but against a combination of antigens called cardiolipin, cholesterol, and lecithin. Although it is an easy-to-perform test, precisely because it does not directly investigate Treponema pallidum, there is a greater risk of false-positive results.
VDRL is the simplest and most widely used screening test for syphilis. Its result is given in dilution forms, ie a 1/8 (1: 8) result means that the antibody has been identified up to 8 dilutions; a 1/64 result shows that we can detect antibodies even after diluting the blood 64 times. The higher the dilution in which the antibody is still detected, the more positive the result. If you found the explanation to be confusing, just know that the 1/2 VDRL is a title lower than 1/4, which is lower than 1/8, and so on. The higher the title, the more positive the exam.
VDRL usually stays positive 4 to 6 weeks after contamination. Generally, their values begin to rise one to two weeks after the onset of hard cancer. Therefore, if the test is done early, one or two days after the onset of the syphilis lesion, the result may give false negative.
Treponemal tests - FTA-ABS, MHA-TP / TPHA / TPPA and ELISA
The treponemal tests are those that directly investigate the bacterium Treponema pallidum. Although more specific, they are more complex to perform, which is why they are not usually used as the first option for screening.
FTA-ABS is the most commonly used treponemal test. Its immunological window is shorter and may be positive within days after the onset of hard cancer and its false positive rate is lower than that of VDRL.
Once positive, the FTA-ABS will thus remain, even after the patient has healed. VDRL values drop progressively after healing, becoming negative after a few years.
Usually, VDRL is used for disease screening and FTA-ABS for confirmation when the first test is positive.
Note: FTA-ABS is slightly superior to TPHA, presenting a greater sensitivity.
Interpretation of results
During the investigation of syphilis, we may encounter the following situations:
Positive VDRL and positive FTA-ABS confirm the diagnosis.
Positive VDRL and negative FTA-ABS indicate a disease other than syphilis.
VDRL negative and positive FTA-ABS indicate syphilis in the early stage, already cured or in the tertiary phase.
Negative VDRL and negative FTA-ABS rule out the diagnosis of syphilis (there are rare cases in which the test is done very early, and there may be false negatives in both).
Syphilis treatment changes according to the stage of the disease:
Primary, secondary or early latent syphilis: Benzathine penicillin (Benzetacil) 2.4 million units in a single dose.
Cases involving neurological system (neurosyphilis) should not be treated with benzathine penicillin , but with crystalline penicillin G or procaine penicillin G.
Treatment should always be done with penicillin, including pregnant women and breastfeeding women. Other antibiotics should only be used if the patient is allergic to penicillin.
In some cases, such as in infection in pregnant women, a treatment may be indicated to desensitize the allergic patient so that she can be treated with penicillin.
Patients with a penicillin allergy may be treated with doxycycline (100 mg twice daily for 14 days) or azithromycin (single dose 2 grams), but they are not as effective as penicillin and there is a greater risk of inducing resistance.
Every treated patient should redo VDRL at 6 and 12 months. The syphilis cure criterion is the disappearance of symptoms and a drop of 4 titers in antibody levels. Examples:
The more time passes, the more titres fall, and may even become negative after a few years (there are healed patients who stay their entire life with low titers such as 1/2 or 1/4). VDRL does not need to be negative to cure syphilis.
The titres in primary syphilis fall faster than in the secondary and tertiary forms. FTA-ABS does not serve to control treatment, because, as already explained, it does not become negative after the cure. Once positive, the FTA-ABS will stay that way for the rest of your life. This is what we call the immunological scar.