Syphilis

Background

Syphilis, a genital ulcerative disease, causes significant complications if untreated and facilitates the transmission of HIV. Untreated early syphilis in pregnant women results in perinatal death in up to 40% of cases and, if acquired during the four years preceding pregnancy, may lead to infection of the fetus in 80% of cases.¹

The rate of P&S syphilis reported in the United States decreased during the 1990s; in 2000, the rate was the lowest since reporting began in 1941 (Figure 30). The low rate of infectious syphilis and the concentration of the majority of syphilis cases in a small number of geographic areas in the United States led to the development of the CDC’s National Plan to Eliminate Syphilis, which was announced by Surgeon General David Satcher in October 1999 and revised in May 2006.²

Although the rate of P&S syphilis in the United States declined 89.7% between 1990 and 2000, the rate of P&S syphilis increased annually between 2001 and 2008. Overall increases in rates between 2001 and 2008 were observed primarily among men (increasing from 3.0 cases per 100,000 population to 7.6 cases per 100,000 population). After persistent declines from 1992 to 2003, the rate of P&S syphilis among women increased from 0.8 cases per 100,000 population in 2004 to 1.5 cases per 100,000 population in 2008.

Syphilis remains an important problem in the South and in urban areas in other regions of the country. Increases in cases among MSM (including men who have sex with women and men) have occurred and have been characterized by high rates of HIV co-infection and high-risk sexual behaviors.^3-7 The estimated proportion of P&S syphilis cases attributable to MSM increased from 4% in 2000 to 62% in 2004.^{8, 9} In 2005, CDC requested that all state health departments report sex of sex partners for persons with syphilis. In 2008, 63% of those P&S syphilis cases in 44 states and Washington, D.C. with available information were among MSM. Of reported male cases with P&S syphilis, sex of partner information in 2008 was available for 80%.

Syphilis—All Stages (P&S, Early Latent, Late, Late Latent, Congenital)

Between 2007 and 2008, the number of cases of early latent syphilis reported to CDC increased 15.2% (from 10,768 to 12,401), while the number of cases of late and late latent syphilis increased 9.3% (from 18,256 to 19,945) (Table 1). The total number of cases of syphilis (all stages: P&S, early latent, late, late latent, and congenital syphilis) reported to CDC increased 13.1% (from 40,921 to 46,277) between 2007 and 2008 (Table 1).

P&S Syphilis—United States

In 2008, P&S syphilis cases reported to CDC increased to 13,500 from 11,466 in 2007, an increase of 17.7%. The rate of P&S syphilis in the United States in 2008 (4.5 cases per 100,000 population) was 18.4% higher than the rate in 2007 (3.8 cases per 100,000 population) (Figure 30, Table 1).

P&S Syphilis by Region

The South accounted for 49.7% of the P&S syphilis cases in 2008 and 48.8% in 2007. Between 2007 and 2008, rates increased 19.6% in the South (from 5.1 to 6.1 cases per 100,000 population), 8.8% in the Northeast (from 3.4 to 3.7), 7.5% in the West (from 4.0 to 4.3) and 36.8% in the Midwest (from 1.9 to 2.6) (Figure 32, Table 25).

P&S Syphilis by State

In 2008, P&S syphilis rates in three states were less than or equal to the HP 2010 target of 0.2 case per 100,000 population (Figure 33, Table 24). Four states reported five or fewer cases of P&S syphilis in 2008 (Table 24) (See the Appendix [Interpreting STD Surveillance Data section] for an explanation of HP2010 target setting methods).

P&S Syphilis by Metropolitan Statistical Area (MSA)

The rate of P&S syphilis in 2008 for the 50 most populous MSAs (6.2) exceeded the HP 2010 target of 0.2 case per 100,000 population (Table 28).

P&S Syphilis by County

In 2008, 2,180 of 3,141 counties (69.3%) in the United States reported no cases of P&S syphilis compared with 2,275 (72.4%) in 2007. Of 966 counties reporting at least one case of P&S syphilis in 2008, four (0.4%) had rates at or below the HP2010 target of 0.2 cases per 100,000 population. Rates of P&S syphilis were above the HP2010 target for 962 counties in 2008 (Figure 34). These 962 counties (30.6% of the total number of counties in the United States) accounted for over 99.9% of the total P&S syphilis cases reported in 2008. In 2008, half of the total number of P&S syphilis cases were reported from 26 counties and two cities (Table 31).

P&S Syphilis by Sex

The rate of P&S syphilis increased 15.2% among men (from 6.6 cases to 7.6 cases per 100,000 men) between 2007 and 2008 (Figure 31, Table 27). During this time, the rate increased 36.4% among women from 1.1 to 1.5 cases per 100,000 women (Figure 31, Table 26).

P&S Syphilis by Age

In 2008, the rate of P&S syphilis was highest in persons in the 20- to 24-year-old and 25- to 29-year-old age groups (11.4 and 10.7 cases per 100,000 population, respectively) (Table 33 and Figure 35–37).

Between 2007 and 2008, P&S syphilis rates in most age groups among men and women increased (Table 33 and Figures 35–37).

P&S Syphilis by Race/Ethnicity

From 2007 to 2008, the rate of P&S syphilis increased in all racial and ethnic groups except American Indian/Alaska Natives (Figure 38). The rate increased 10.0% among non-Hispanic whites (from 2.0 to 2.2 cases per 100,000 population), 25.4% among blacks (from 13.8 to 17.3), 11.9% among Hispanics (from 4.2 to 4.7), and 25.0% among Asian/Pacific Islanders (from 1.2 to 1.5). The rate decreased 32.4% (from 3.4 to 2.3 cases per 100,000 population) among American Indian/Alaska Natives (Table 34B).

P&S Syphilis by Sex and Sex Behavior

The male-to-female rate ratio for P&S syphilis has risen steadily since 1996, when it was 1.2, consistent with an increase in MSM (Figure 31). In 2008, however, the rate of P&S syphilis in males was 5.1 times that in females, a small decrease from 6.0 in 2007.

In 2005, CDC began collecting information on sex partners of patients with P&S syphilis. In 2008, this information was available for 80% of male cases.

In 2008, the stage of disease was reported as follows: among heterosexual men (men who have sex with women exclusively) with P&S syphilis, 41.6% had primary syphilis and 58.4% had secondary syphilis. Among female patients, 16.6% had primary syphilis and 83.4% had secondary syphilis. Among MSM with P&S syphilis, 24.5% had primary syphilis and 75.5% had secondary syphilis (Figure 39).

Of females with P&S syphilis, 22.4% were white, 64.4% were black, 9.7% were Hispanic, and 3.6% were of other races/ethnicities. Of heterosexual men, 16.9% were white, 65.8% were black, 13.4% were Hispanic, and 3.9% were of other races/ethnicities. Of MSM, 41.2% were white, 33.6% were black, 18.8% were Hispanic, and 6.4% were of other races/ethnicities (Figure 40).

P&S Syphilis by Race/Ethnicity and Sex

From 2007 to 2008, the P&S syphilis rate among non-Hispanic white males increased 8.1% (from 3.7 to 4.0), and increased among non-Hispanic white females as well (from 0.4 to 0.5). The rate increased 22.3% among black males (from 22.9 to 28.0) and 38.2% among black females (from 5.5 to 7.6). The rate increased 12.3% among Hispanic males (from 7.3 to 8.2), and 25.0% among Hispanic females (from 0.8 to 1.0). The rate increased 25.0% for Asian/Pacific Island males (from 2.4 to 3.0), but remained unchanged for Asian/Pacific Island females (0.1). The rate decreased 23.8% among American Indian/Alaska Native males (from 4.2 to 3.2) and decreased 46.2% among American Indian/Alaska Native females (from 2.6 to 1.4) (Table 34B).

P&S Syphilis by Race/Ethnicity, Age, and Sex

In 2008, the rate of P&S syphilis among blacks was highest among women 20 to 24 years of age (25.3–a 59.1% increase from 15.3 in 2007) and among men 20 to 24 years of age (75.1–a 31% increase from 57.2 in 2007) and 25 to 29 years of age (65.6–an 18% increase from 55.5 in 2007). For non-Hispanic whites, the rate was highest among women 20 to 24 years of age (1.4) and among men 40 to 44 years of age (9.8). For Hispanics, the rate was highest among women 20 to 24 years of age (2.8) and among men 35 to 39 years of age (16.3). For Asian/Pacific Islanders, the rate was highest among women 25 to 29 years of age (0.7) and among men 30 to 34 years of age (7.5). For American Indian/Alaska Natives, the rate was highest among women 30 to 34 years of age (4.0) and among men 25 to 29 years of age (11.7) (Table 34B).

P&S Syphilis by Reporting Source

In 1990, 25.6% of P&S syphilis cases were reported from sources other than STD clinics; this figure increased to 39.2% in 1998. Between 1998 and 2008, the proportion of P&S syphilis cases reported from sources other than STD clinics increased from 39.2% to 66.0% (Figure 41 and Table A2). Between 2001 and 2008, the number of cases among males reported from non-STD clinic sources increased sharply while the number from STD clinics increased only slightly (Figure 41 ).

During 2008, patients with P&S syphilis primarily sought care with private physicians or STD clinics. More cases of syphilis among MSM were reported from private physicians (36.9%) than STD clinics (30.2%) (Figure 42). More cases among women and heterosexual men were reported from STD clinics than private physicians.

Congenital Syphilis—United States

The rate of congenital syphilis remained unchanged between 2007 and 2008 (10.1 cases per 100,000 live births) although there was a 16% rate increase between 2006 and 2007 (Table 40). In 2008, 431 cases were reported (the same number reported in 2007), an increase from 372 in 2006. The increase in the rate of congenital syphilis since 2005 when the rate reached a nadir at 8.2 cases per 100,000 live births may relate to the increase in the rate of P&S syphilis among women that has occurred since 2004 (Figure 43).

In 2008, 27 states and one outlying area had one or more cases of congenital syphilis (Tables 39 and 40).

Syphilis among Special Populations

Additional information about syphilis and congenital syphilis in racial and ethnic minority populations, adolescents, MSM, and other at-risk populations is found in the Special Focus Profiles.

Syphilis Summary

In recent years, MSM have accounted for an increasing number of syphilis cases in the United States;⁹ 63% of reported P&S syphilis cases in the United States are among MSM, based on information from 44 states and Washington, D.C. Although the majority of U.S. syphilis cases have occurred among MSM, syphilis among heterosexuals is an emerging problem.¹⁰

¹ Ingraham NR. The value of penicillin alone in the prevention and treatment of congenital syphilis. Acta Derm Venereol 1951, 31 (suppl 24):60–88.

² Centers for Disease Control and Prevention. The National Plan to Eliminate Syphilis from the United States. Atlanta, GA: U.S. Department of Health and Human Services; May 2006

³ Centers for Disease Control and Prevention. Resurgent bacterial sexually transmitted disease among men who have sex with men–King County, Washington, 1997–1999. MMWR 1999;48:773–777

⁴ Centers for Disease Control and Prevention. Outbreak of syphilis among men who have sex with men–Southern California, 2000. MMWR 2001;50(7):117–20.

⁵ Centers for Disease Control and Prevention. Primary and secondary syphilis among men who have sex with men–New York City, 2001. MMWR 2002;51:853–6.

⁶ Chen SY, Gibson S, Katz MH, Klausner JD, Dilley JW, Schwarcz SK, Kellogg TA, McFarland W. Continuing increases in sexual risk behavior and sexually transmitted diseases among men who have sex with men: San Francisco, California, 1999–2001 [Letter]. Am J Public Health 2002;92:1387–8.

⁷ D’Souza G, Lee JH, Paffel JM. Outbreak of syphilis among men who have sex with men in Houston, Texas. Sex Transm Dis 2003;30:872–3.

⁸ Centers for Disease Control and Prevention. Primary and secondary syphilis–United States, 2003–2004. MMWR 2006;55:269–73.

⁹ Heffelfinger JD, Swint EB, Berman SM, Weinstock HS. Trends in primary and secondary syphilis among men who have sex with men in the United States. Am J Public Health 2007;97:1076–1083.

¹⁰ Centers for Disease Control and Prevention. Primary and secondary syphilis—Jefferson County, Alabama, 2002–2007. MMWR 2009;58:463–467.