What is syphilis? |

Causes and Symptoms

Syphilis is a sexually transmitted disease (STD) resulting from infection by Treponema palladum. The history of the disease is unclear. Evidence exists that its origin may have been linked with a disease, yaws, found in the Western Hemisphere at the time of explorer Christopher Columbus (1451–1506). Yaws is a relatively mild disease generally transmitted through contaminated objects or open skin
lesions, but not generally through sexual transmission; it results from infection by a subspecies of Treponema called T. palladum ssp. pertenue. The theory suggests that this may have been the form of the disease brought back to Europe on one of Columbus’s ships. Mutation and sexual transmission in the population of Europe may have produced the more serious form of the disease.

The disease is characterized by several distinct stages. Initial exposure to the organism during sexual intercourse results in formation of a painless skin lesion called a chancre at the site of infection (primary syphilis), developing anywhere from a week to months after infection. Spirochete
bacteria may be isolated from the lesion, as well as being found live inside white blood cells (macrophages and neutrophils) that infiltrate the area. The white cells may be a mechanism for systemic spread of the organism. The lesion generally heals spontaneously, leaving the impression that the disease has been eliminated.

During the weeks after formation of the chancre, the spirochetes multiply to large numbers and become disseminated throughout the body. A second stage (secondary syphilis) often appears within two months following regression of the chancre. Symptoms are often described as flu-like, with malaise, headache, fever, and joint aches. A skin rash often appears, covering most of the body. Sores may develop in the mouth and throat and on many of the mucous membranes in the body. The organism is highly transmissible during this period. The rash and other symptoms generally fade over a period of weeks.

Approximately 10 percent of untreated cases develop a third, or tertiary, stage of syphilis. The organism can infiltrate any organ or system in the body, resulting in soft tumors (gummas) in the eyes, lungs, bone, brain, or other organs. Symptoms are characteristic of the organ infected. For example, infection of the brain or other areas of the central nervous system are described as neurosyphilis or syphilitic dementia, characterized by memory loss, personality changes, and neurodegeneration. Even if tertiary syphilis is treated, prognosis for the patient at this stage is often poor.

Treponema has the ability to cross the placenta, and the infection of a pregnant woman may result in congenital syphilis, or infection of her unborn child. Infection may kill the fetus or cause it to be born with obvious deformities such as blindness or physical abnormalities. The infant may also be asymptomatic. An undiagnosed infection will likely progress, with symptoms appearing within weeks after birth. It is common for a rash to appear, with evidence of tertiary stage neurosyphilis or cardiovascular syphilis.

A diagnosis of syphilis can be made through microscopic examination of lesion exudates, noting the presence of spirochetes. However, Treponema is notoriously unstable, and the test must be made shortly after obtaining the specimen. More commonly, diagnosis is based upon serological testing for serum antibodies against the organism or tissue lipids released from infected or damaged cells.

Treatment and Therapy

Penicillin is the preferred method of treatment for both primary and secondary syphilis. If the disease has progressed to the tertiary stage, then antibiotic treatment will still eliminate the organism, but it will not reverse organ damage that may have occurred. Treatment for related organ involvement is symptomatic.

Alternative antibiotics include erythromycin, tetracyclines, and chloramphenicol, if necessary. However, only penicillin is effective during the tertiary stage or for use in pregnant women.

Perspective and Prospects

Despite the long-time existence of effective therapy, penicillin or alternative antibiotics, and the absence of any reservoir for T. palladum other than humans, syphilis remains the third most common sexually transmitted bacterial disease in the West. Only gonorrhea and chlamydia are more common.

As a result of effective therapy and the generally obvious symptoms of the disease, tertiary syphilis has largely disappeared. However, sexual practices continue to sustain spread of the disease. The Centers for Disease Control and Prevention estimate that 55,400 people acquire new syphilis infections each year in the United States. Three factors are primary contributors to the resurgence of the disease: prostitution, the increase in riskier sexual practices among homosexual men, and general apathy toward a disease that is relatively easy to treat in its early stages. An increase in congenital syphilis also reflects the presence of the disease in women of childbearing years. In the absence of condom use, both unwanted pregnancy and the spread of STDs such as syphilis may result.

No vaccine currently exists for syphilis. The inability to culture the organism in the laboratory has made research related to Treponema difficult, and the organism does not infect animals other than humans to act as a method of vaccine production. However, genetic engineering has resulted in the cloning of several bacterial gene products related to surface proteins and virulence factors, allowing the possibility for a vaccine in the future. For now, the best means of controlling syphilis remains the prevention of its spread through education and safer-sex practices, as well as early treatment of those infected.

Bibliography

Centers for Disease Control and Prevention. The National Plan to Eliminate Syphilis from the United States. Atlanta: U.S. Department of Health and Human Services, 2006.

Centers for Disease Control and Prevention. "Syphilis—CDC Fact Sheet." Centers for Disease Control and Prevention: Sexually Transmitted Diseases (STDs), February 11, 2013.

Mandell, Gerald L., John E. Bennett, and Raphael Dolin, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. New York: Churchill Livingstone/Elsevier, 2010.

Murray, Patrick R., Ken S. Rosenthal, and Michael A. Pfaller. Medical Microbiology. 7th ed. Philadelphia: Elsevier/Saunders, 2013.

Parker, James N., and Philip M. Parker, eds. The Official Patient’s Sourcebook on Syphilis. ICON Group, 2009.

Scholten, Amy. "Syphilis." Health Library, May 16, 2013.

Quetel, Claude. The History of Syphilis. Baltimore: Johns Hopkins University Press, 1990.

Sutton, Amy L., ed. Sexually Transmitted Diseases Sourcebook. 3d ed. Detroit, Mich.: Omnigraphics, 2006.