Syphilis in acute and late stages is still prevalent in the developing world and is becoming an emerging problem again in sub-populations of developed countries.
What is syphilis?
Syphilis is an infectious sexually transmitted disease caused by the bacterium Treponema pallidum (T. pallidum). Syphilis can be acquired through sexual contact or direct contact with infected sores via skin or mucous membranes. Syphilis can also be vertically transmitted placentally from a mother to the foetus.
Clinical Features – Signs and Symptoms
T. pallidum penetrates the mucous membrane or microscopic dermal abrasions at the site of an infection and enters the blood and lymphatics to cause a systemic infection. There are 4 stages of syphilis that each present with different symptoms and are summarised as follows:
Primary Syphilis
Symptoms occur about 3 weeks after skin contact with the organism. The initial lesion is a red papule which ulcerates to form a painless ulcer with raised edges. The ulcer (chancre) can occur anywhere on the external genitalia, in the vagina, on the cervix, within the urethra, anal canal, mouth or pharynx.
Chancres are also associated with a painless rubbery lymphadenopathy that takes 3 to 4 weeks to heal, leaving a thin scar.
Secondary syphilis
This stage occurs 6 to 10 weeks after the first ulcer appears. Symptoms at this stage may regress and reappear and they include:
- Malaise
- Headache and mild fever
- Skin rash (80% patients) rose pink, macula, slightly itchy – palms and soles
- Moist areas of skin papules may become eroded and form wart-like lesions (condyloma lata) and is commonly seen in nasolabial folds around the mouth and perianal area
Other complications can include:
- Patchy hair loss (alopecia)
- Diffuse lymphadenopathy
- Joint and bone aches and pains
- Mucosal lesions in 30% of patients that present as shallow ulcers with a greyish adherent membrane seen in the mouth, hard palate, tonsils and on the genitalia.
Latent syphilis
In this stage, the lesions of secondary syphilis have healed and infection can only be detected by serological testing. Latent syphilis that is acquired within the preceding 2 years of the initial infection is referred to as early latent syphilis. All other cases are either late latent or latent syphilis.
If this stage is not detected, patients are at risk of developing complications of tertiary syphilis in 20 to 30 years. Up to 40% of untreated patients will develop tertiary syphilis.
Tertiary syphilis
The most common sign in tertiary syphilis is the development of gumma, which is an area of tissue death due to chronic inflammatory responses that lead to tissue destruction and scarring. Gummas can affect the heart and nervous system, and they can also cause aortic regurgitation or aortic aneurysms.
Congenital Syphilis
Universal screening for syphilis in pregnant women is essential in preventing congenital syphilis. T. pallidum can cross the placenta during pregnancy, and through procedures like amniocentesis, has been found to cause foetal infection as early as 10 to 14 weeks of gestation.
Babies born with congenital syphilis risk being born with:
- Hutchinson’s teeth (notched incisor)
- Scarring of skin from gummata
- Depressed nasal bridge
- Corneal scarring from keratitis
- Perforation of hard palate
- Chronic hepatitis
- Bone lesions
Diagnosis
Serological testing
- The Fluorescent Treponemal Antibody Absorption (FTA-ABS) test detects antibodies against the T. pallidum bacteria and is the most sensitive test for early detection.
- The Venereal Disease Research Laboratory (VDRL) test specifically screens for syphilis and detects antibodies at low costs.
- The Treponema Pallidum Hemagglutination (TPA) test detects T. pallidum antibodies via the haemagglutination method.
All sexual partners and children should be screened if latent syphilis is suspected.
Antenatal screening
Serology testing is performed as part of antenatal screening. Unexpected positive results are rarely due to acute infectious syphilis and are more likely to be due to old unrecognised infections. These patients are not infectious to their sexual partners but are at risk of late complications of tertiary syphilis.
Individuals with syphilis for more than 4 years are not sexually infectious but there is still a risk of transmission to the child during pregnancy.
Management
Syphilis is easy to cure if diagnosed in the early stages. The antibiotic, penicillin G, is recommended at all stages of infection and has shown effectiveness in killing T. pallidum. However, the choice of regimen depends on patient compliance.
- Benzathine penicillin 1.8g injected intramuscularly as a single dose for acute syphilis or as a course of 3 injections at weekly intervals for latent syphilis
- Procaine penicillin 1g injected intramuscularly daily for 10 days for acute syphilis and for 15 days for latent syphilis
- Treatment via injection and the length of treatment depends on the stage of infection
- Screening for syphilis and other sexually transmitted infections is recommended for the individual and all their sexual partners for the preceding 2 years
Individuals allergic to penicillin can be treated with oral courses of doxycycline or erythromycin or be put on a penicillin desensitization regimen.
In the case of female patients who have positive serology test results for latent syphilis, their children should also be screened to ensure there has been no unrecognised congenital infection.
