Syphilis is a sexually transmitted infection (STI) caused by a spirochaete bacterium, Treponema pallidum. Syphilis has many alternate names, including "lues", "syph", "the Pox" (or "great pox", to distinguish it from smallpox), and the "French disease."
The route of transmission of syphilis is almost invariably by sexual contact. However, there are examples of direct contact infections and of congenital syphilis (transmission from mother to child in utero).
The signs and symptoms of syphilis are myriad; before the advent of serological testing, diagnosis was more difficult and the disease was dubbed the "Great Imitator" because it was so often confused with other diseases.
Syphilis can be treated with penicillin or other antibiotics. Statistically, oral treatment is dramatically less effective than other treatments, because patients tend not to complete the course. The oldest, and still most effective, method is to inject benzathine penicillin into each buttock (procaine is added to make the pain bearable); the dose must be given half in each buttock because the amount given would be too painful if given in a single injection.
Another treatment is to administer several tablets of azithromycin (which has a long duration of action) orally under observation. This latter course may soon be obsolete, as strains of syphilis resistant to azithromycin have developed, and accounted for 10% of cases in some areas in 2004. Other treatments are less effective as the patient is required to take pills several times a day.
If not treated, syphilis can cause serious effects such as damage to the nervous system, heart, or brain. Untreated syphilis can be fatal.
Stages of syphilis
Different manifestations occur at each stage of the disease:
Primary syphilis
Primary syphilis is manifested after an incubation period of 10-90 days (the average is 21 days) with a primary sore. During the initial incubation period, individuals are asymptomatic. The sore, called a chancre, is a firm, painless skin ulceration localized at the point of initial exposure to the bacterium, often on the penis, vagina or rectum. Local lymph node swelling can occur. The primary lesion may persist for 4 to 6 weeks and then heal spontaneously.
Secondary syphilis
Secondary syphilis is characterized by a skin rash that appears 1-6 months (commonly 6 to 8 weeks) after the primary infection. This is a symmetrical reddish-pink non-itchy rash on the trunk and extremities, which unlike most other kinds of rash involves the palms of the hands and the soles of the feet; in moist areas of the body the rash becomes flat broad whitish lesions called condylomata lata. Mucous patches may also appear on the genitals or in the mouth. A patient with syphilis is most contagious when he or she has secondary syphilis.
Other symptoms common at this stage include fever, sore throat, malaise, weight loss, headache, meningismus, and enlarged lymph nodes. Rare manifestations include an acute meningitis that occurs in about 2% of patients, hepatitis, renal disease, hypertrophic gastritis, patchy proctitis, ulcerative colitis, rectosigmoid mass, arthritis, periostitis, optic neuritis, iritis, and uveitis.
Tertiary syphilis
Tertiary syphilis occurs from as early as one year after the initial infection but can take up to ten years to manifest - though cases have been reported where this stage has occurred fifty years after initial infection. This stage is characterised by gummas, soft, tumor-like growths, readily seen in the skin and mucous membranes, but which can occur almost anywhere in the body, often in the skeleton. Other characteristics of untreated syphilis include Charcot's joints (joint deformity), and Clutton's joints (bilateral knee effusions). The more severe manifestations include neurosyphilis and cardiovascular syphilis.
Neurological complications at this stage include generalized paresis of the insane which results in personality changes, changes in emotional affect, hyperactive reflexes, and Argyll-Robertson pupils, a diagnostic sign in which the small and irregular pupils constrict in response to focusing the eyes, but not to light; Tabes dorsalis, also known as locomotor ataxia, a disorder of the spinal cord, often results in a characteristic shuffling gait.
Cardiovascular complications include aortic aortitis, aortic aneurysm, aneurysm of sinus of Valsalva, and aortic regurgitation, and are a frequent cause of death. Syphilitic aortitis can cause de Musset's sign (a bobbing of the head that de Musset first noted in Parisian prostitutes).
Latent syphilis
Latent syphilis is defined as having serologic proof of infection without signs or symptoms of disease. Latent syphilis is further described as either early or late. Early latent syphilis is defined as having syphilis for one year or less from time of initial infection without signs or symptoms of disease. Late latent syphilis, then, is infection for greater than one year but having no clinical evidence of disease. The distinction is important for two reasons, therapy and risk for transmission.
In practice, the time of initial infection is often not known and in this case should then be presumed to be late for the purpose of therapy. Early latent syphilis may be treated with a single IM injection of a long-acting penicillin. Late latent syphilis, however, requires three such injections, each a week apart. For infectiousness, however, late latent syphilis is not considered contagious while early latent is. Thus, if the duration of infection is not known, one should presume the patient is early and contagious.
Congenital syphilis
Congenital syphilis is syphilis present in utero and at birth, and occurs when a child is born to a mother with secondary or tertiary syphilis. Fetus in the utero is most liable to be infected with syphilis after the fifth month. According to the CDC, 40% of births to syphilitic mothers are stillborn, 40-70% of the survivors will be infected, and 12% of these will subsequently die prematurely. Manifestations of congenital syphilis include abnormal x-rays; Hutchinson's teeth (centrally notched, widely-spaced peg-shaped upper central incisors); mulberry molars (sixth year molars with multiple poorly developed cusps); frontal bossing; saddle nose; poorly developed maxillae; enlarged liver; enlarged spleen; petechiae; other skin rash; anemia; lymph node enlargement; jaundice; pseudoparalysis; and snuffles, the name given to rhinitis in this situation. Rhagades, linear scars at the angles of the mouth and nose result from bacterial infection of skin lesions. Death from congenital syphilis is usually through pulmonary hemorrhage. Affected children are highly infectious until about 2 years of age.
Testing
It was only in the 20th century that effective tests and treatments for syphilis were developed.
In 1906, the first effective test for syphilis, the Wassermann test, was developed. Although it had some false positive results, it was a major advance in the prevention of syphilis. By allowing testing before the acute symptoms of the disease had developed, this test allowed the prevention of transmission of syphilis to others, even though it did not provide a cure for those infected. In the 1930s the Hinton test, developed by William Augustus Hinton, and based on flocculation, was shown to have fewer false positive reactions than the Wasserman test. Both of these early tests have been superseded.
Present-day syphilis tests, such as the Rapid Plasma Reagin (RPR) and Venereal Disease Research Laboratory (VDRL) tests, while useful, are still not completely specific, as many other conditions can cause a positive result. Tests based on monoclonal antibodies and immunofluorescence, including Treponema pallidum haemagglutination assay (TPHA) and Fluorescent Treponemal Antibody Absorption (FTA-ABS), are more specific, but are still unable to rule out related treponomal infections such as yaws and pinta. However, a simple microscopy of chancre fluid using dark ground illumination provide a quick and effective test.
In one of the best-documented episodes of unethical human medical experimentation in the twentieth century, the Tuskegee syphilis study continued to study the lifetime course of syphilis in a group of African Americans long after effective treatments for syphilis were available. In the July 17, 1998 issue of the journal Science, a group of biologists reported complete sequencing of the genome of T. pallidum.
Treatment
There were originally no effective treatments for syphilis. The most common in use were guaiacum and mercury: the use of mercury gave rise to the saying "A night in the arms of Venus leads to a lifetime on Mercury". Though no proper studies were done to prove it, mercury may have been an effective means to treat syphilis. It was administered multiple ways including by mouth and by rubbing it on the skin. One of the more fascinating methods was fumigation, in which the patient was placed in a closed box with their head sticking out. Mercury was placed in the box and a fire was started under the box which caused the mercury to vaporize. It was a gruelling process for the patient and the least effective for delivering mercury to the body.
As the disease became better understood, more effective treatments were found, beginning with the use of the arsenic-containing drug Salvarsan from 1910, and later, Neosalvarsan.
Unfortunately, these drugs were not 100% effective, especially in late disease. It had been observed that some who develop high fevers could be cured of syphilis. Thus, for a brief time malaria was used as treatment because it produces prolonged and high fevers. This was considered an acceptable risk because the malaria could later be treated with quinine which was available at that time. Malaria as a treatment for syphilis was usually reserved for late disease, especially neurosyphilis, and then followed by either Salvarsan or Neosalvarsan as adjuvunct therapy.
These treatments were finally rendered obsolete by the discovery of penicillin, and its widespread manufacture after World War II allowed syphilis to be effectively cured for the first time.
To this day, the first choice treatment for syphilis remains penicillin, in the form of benzathine penicillin G or aqueous procaine penicillin G injections. Individuals who have severe allergic reactions to penicillin (e.g., anaphylaxis) may be effectively treated with oral tetracyclines.
Oral Azithromycin given as a single dose of 2g has been used successfully to treat syphilis in a pilot study of 328 patients in Tanzania (Riedner 2005), but resistance to azithromycin has been reported in the US and elsewhere, which makes it doubtful that this treatment will become widespread in the US.
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