Syphilis

Article By:

Stamm, Lola V. Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, North Carolina.

Last reviewed:September 2019

DOI:https://doi.org/10.1036/1097-8542.675600

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• Syphilis, published June 2014:Download PDF Get Adobe Acrobat Reader

A sexually transmitted infection of humans caused by Treponema pallidum. Syphilis is an infectious disease caused by a corkscrew-shaped motile bacterium (spirochete), Treponema pallidum (specifically, T. pallidum subspecies pallidum in the family Spirochaetaceae) [see illustration], and is transmitted principally by sexual intercourse. Because of its narrow width, the spirochete cannot be seen by light microscopy, but can be observed with staining procedures (silver stain or immunofluorescence) and with dark-field, phase-contrast, or electron microscopy. Treponema pallidum is very sensitive to environmental conditions and to physical and chemical agents. The complete genome sequence of T. pallidum has been determined. Analysis of the nucleotide sequence of the small, circular treponemal chromosome indicates that T. pallidum lacks the genetic information for many of the metabolic activities found in other bacteria. Thus, this spirochete is dependent upon the host for most of its nutritional requirements. See also: Bacteria; Chromosome; Electron microscope; Immunofluorescence; Infection; Infectious disease; Medical bacteriology; Sexually transmitted diseases

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