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Epidemiology
Syphilis is a systemic sexually acquired infection whose
etiologic agent is Treponema pallidum. Syphilis remains chronic without treatment and progresses in stages characterized by episodes of active disease interrupted by periods of latent infection. The
incubation period is estimated to be between 10 and 90 days (average 3 weeks).
Syphilis has often been called "the great imitator" because so many of the signs and symptoms may be difficult to distinguish from those of other diseases. Early clinical manifestations (primary and secondary stages) primarily involve the skin and mucosal surfaces
although secondary syphilis is a systemic illness. Latent disease has no clinical signs or symptoms. Late manifestations may affect virtually any organ system, and neurosyphilis can occur at any stage of syphilis.
Transmission
The major routes of transmission are sexual and
vertical (in utero from infected pregnant woman via
hematogenous
spread to her fetus). An infected individual is
primarily contagious to sex partners during the primary and
secondary stages of infection when infectious lesions or
rash are present.
Incidence
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Estimated Annual Incidence of Selected STDs in the U.S.
, 2000 |
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Trichomoniasis
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7.4 million
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Human Papillomavirus (HPV)
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6.2 million
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Chlamydia
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2.8 million
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Herpes Simplex Virus (HSV) Type 2
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1.6 million
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Gonorrhea
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718,000
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Syphilis
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37,000
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Syphilis was distributed widely throughout the U.S. after the 1940s. Incidence declined rapidly after the introduction of penicillin therapy and broad-based public health programs. Between 1986 and 1990, there was a dramatic rise (83% increase) in the incidence of infectious (primary and secondary) syphilis; some
researchers have linked this increase to the use of crack cocaine.
During the 1990s, reported cases of syphilis decreased on average approximately 15% each year. By the late 1990s, syphilis rates in the U.S. had declined to a point where public health authorities declared syphilis elimination a feasible goal. In 2000, the reported rate of syphilis in the U.S. was at an all-time low.
The
rate of P & S syphilis has increased from 2001-2006; this
increase was observed primarily in men. CDC has developed a national plan to eliminate syphilis, which includes rapid case identification and reporting.
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