Syphilis

What is syphilis?

Syphilis is an STD that has been around for centuries. It is caused by a microscopic bacterial organism called a spirochete. The scientific name for the organism is Treponema pallidum. The spirochete is a wormlike, spiral-shaped organism that wiggles vigorously when viewed under a microscope. It infects the person by burrowing into the moist, mucous-covered lining of the mouth or genitals. The spirochete produces a classic, painless ulcer known as a chancre.

Symptoms of syphilis

There are three stages of syphilis, along with an inactive (latent) stage. Formation of an ulcer (chancre) is the first stage. The chancre develops any time from 10 to 90 days after infection, with an average time of 21 days following infection until the first symptoms develop. Syphilis is highly contagious when the ulcer is present. The infection can be transmitted from contact with the ulcer which teems with spirochetes. If the ulcer is outside of the vagina or on the male's scrotum, condoms may not prevent transmission of the infection by contact. Similarly, if the ulcer is in the mouth, merely kissing the infected individual can spread the infection. The ulcer can go away on its own after 3 to 6 weeks, but the disease can recur months later as secondary syphilis if the primary stage is not treated.

In most women, an early infection resolves on its own, even without treatment. However, 25% will proceed to the second stage of the infection called "secondary" syphilis, which develops weeks to months after the primary stage and lasts from 4 to 6 weeks. Secondary syphilis is a systemic stage of the disease, meaning that it can involve various organ systems of the body. In this stage, patients can initially experience many different symptoms, but most commonly they develop a skin rash, typically appearing on the palms of the hands or the bottoms of the feet, that does not itch. Sometimes the skin rash of secondary syphilis is very faint and hard to recognize; it may not even be noticed in all cases. This secondary stage can also include hair loss, sore throat, white patches in the nose, mouth, and vagina, fever, and headaches. There can be lesions on the genitals that look like genital warts but are caused by spirochetes rather than the wart virus. These wartlike lesions, as well as the skin rash, are highly contagious. The rash can occur on the palms of the hands, and the infection can be transmitted by casual contact.

Subsequent to secondary syphilis, some patients will continue to carry the infection in their body without symptoms. This is the so-called latent stage of the infection. Then, with or without a latent stage, which can last as long as 20 or more years, the third (tertiary) stage of the disease can develop. At this stage, syphilis usually is no longer contagious. Tertiary syphilis is also a systemic stage of the disease and can cause a variety of problems throughout the body including:

The damage sustained by the body during the tertiary stage of syphilis is severe and can even be fatal.

Diagnosis of syphilis

Syphilis can be diagnosed by scraping the base of the ulcer and looking under a special type of microscope (dark field microscope) for the spirochetes. However, since these microscopes are rarely detected, the diagnosis is most often made and treatment is prescribed based upon the appearance of the chancre. Diagnosis of syphilis is complicated by the fact that the causative organism cannot be grown in the laboratory. Therefore, cultures of affected areas cannot be used for diagnosis.

Special blood tests can also be used to diagnose syphilis. The standard screening blood tests for syphilis are called the Venereal Disease Research Laboratory (VDRL) and Rapid Plasminogen Reagent (RPR) tests. These tests detect the body's response to the infection, but not to the actual Treponema organism that causes the infection. These tests are thus referred to as non-treponemal tests. Although the non-treponemal tests are very effective in detecting evidence of infection, they can also produce a positive result when no infection is actually present (so-called false-positive results for syphilis).

Consequently, any positive non-treponemal test must be confirmed by a treponemal test specific for the organism causing syphilis, such as the microhemagglutination assay for T. pallidum (MHA-TP) and the fluorescent treponemal antibody absorbed test (FTA-ABS). These treponemal tests directly detect the body's response to Treponema pallidum.

Treatment of syphilis

Depending on the stage of disease, the treatment options for syphilis vary as summarized in the table below.

Stage of Disease	Preferred Treatment	Alternative Treatments
Primary infection, secondary infection, or early latent infection (for less than 1 year)	Benzathine penicillin injection 2.4 million units (single dose)	Doxycycline 100 mg orally twice per day for 14 days or tetracycline 500 mg orally 4 times per day for 14 days
Late latent infection (for more than1 year), cardiovascular disease, or gumma	Benzathine penicillin G injection 2.4 million units every week for 3 weeks	Doxycycline 100 mg orally twice per day for 28 days or tetracycline 500 mg orally 4 times per day for 28 days
Neurosyphilis (involvement of the nervous system), eye disease	Aqueous crystalline penicillin G 3-4 million units every 4 hours intravenously or 24 million units continuous IV infusion for 10 days	Procaine penicillin injection 2.4 million units each day with probenecid 500 mg orally 4 times per day, both for 10-14 days

"Latent" means no clinical findings, i.e., only diagnosed on the basis of laboratory tests.
"Early latent" means that the duration of infection has been less than 1 year.
"Late latent" means the duration of infection has been more than 1 year.

Women who are infected during pregnancy can pass on the infection to the fetus through the placenta. Penicillin must be used in pregnant patients with syphilis since other antibiotics do not effectively cross the placenta to treat the infected fetus. Left untreated, syphilis can lead to blindness or even death of the infant.