Syphilis

Background

Syphilis, a genital ulcerative disease, causes significant complications if untreated and facilitates the transmission of HIV infection. Untreated early syphilis in pregnant women results in perinatal death in up to 40% of cases and, if acquired during the 4 years before pregnancy, can 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 34). The low rate of P&S 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 CDC’s National Plan to Eliminate Syphilis, which was announced by Surgeon General David Satcher, MD, PhD, in October 1999 and revised in May 2006.²

Although the rate of P&S syphilis in the United States declined 89.7% during 1990–2000, the rate increased annually during 2001–2009 before decreasing in 2010. Overall increases in rates were observed primarily among men (increasing from 3.0 cases per 100,000 population in 2001 to 7.9 cases in 2010). After persistent declines during 1992–2003, the rate among women increased from 0.8 cases (in 2004) to 1.5 cases (in 2008) per 100,000 population, declining to 1.1 cases per 100,000 population in 2010.

Syphilis remains a major health problem in the South and in urban areas in other regions of the country. Increases in cases among MSM (including men having sex with both men and women) 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 7% in 2000 to 64% in 2004.^8,9 In 2005, CDC requested that all state health departments report the sex of sex partners for persons with syphilis. Of reported male cases with P&S syphilis, sex of sex partner information in 2010 was available for 82%.

In 2010, 67% of P&S syphilis cases in 44 states and the District of Columbia that provided information about sex of sex partners were among MSM.

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

During 2009–2010, the number of cases of early latent syphilis reported to CDC increased 4.1% (from 13,066 to 13,604 cases), and the number of cases of late and late latent syphilis increased 4.3% (from 17,338 to 18,079 cases) (Tables 1, 36, and 38). The total number of cases of syphilis (P&S, early latent, late, late latent, and congenital) reported to CDC increased 2.2% (from 44,830 to 45,834 cases) during 2009–2010 (Table 1).

P&S Syphilis—United States

P&S syphilis cases reported to CDC decreased from 13,997 in 2009 to 13,774 in 2010, a decrease of 1.6%. The rate of P&S syphilis in the United States in 2010 (4.5 cases per 100,000 population) was 2.2% lower than the rate in 2009 (4.6 cases) (Figure 34, Table 1). This is the first overall decrease in P&S syphilis in 10 years.

P&S Syphilis by Region

The South accounted for 45.5% of P&S syphilis cases in 2010 and 53.0% in 2009. During 2009–2010, rates decreased 15.4% in the South (from 6.5 to 5.5 cases per 100,000 population) and increased 5.3% in the Northeast (from 3.8 to 4.0 cases), 21.4% in the Midwest (from 2.8 to 3.4 cases), and 16.2% in the West (from 3.7 to 4.3 cases) (Figure 36, Table 26).

P&S Syphilis by State

In 2010, the 15 states and areas (including the District of Columbia) with the highest rates of P&S syphilis accounted for 72% of all U.S. cases of P&S syphilis. The rate of P&S syphilis in 14 of these 15 states and areas (including the District of Columbia) exceeded the national rate of 4.5 cases per 100,000 population; of these 14 states and areas (including the District of Columbia), 9 were in the South (Figure 37, Table 25).

P&S Syphilis by Metropolitan Statistical Area

The rate of P&S syphilis in 2010 for the 50 most populous MSAs (6.3 cases per 100,000 population) (Table 29) exceeded the overall rate for the United States (4.5 cases) (Table 26). The rate increased in 29 of these 50 MSAs (58%) during 2009–2010.

P&S Syphilis by County

In 2010, 2,167 of 3,141 counties (69.0%) in the United States reported no cases of P&S syphilis, compared with 2,194 counties (69.9%) in 2009 (Figure 38). In 2010, half of the total number of P&S syphilis cases was reported from 27 counties and two cities (Table 32).

P&S Syphilis by Sex

The rate of P&S syphilis increased 1.3% among men (from 7.8 to 7.9 cases per 100,000 men) during 2009–2010 (Figure 35, Table 28). During this same period, the rate decreased 21.4% among women (from 1.4 to 1.1 cases per 100,000 women) (Figure 35, Table 27).

P&S Syphilis by Age

In 2010, the rate of P&S syphilis was highest among persons aged 20–24 years and 25–29 years (13.5 and 11.3 cases per 100,000 population, respectively) (Table 34).

During 2009–2010, rates for men increased the most in those aged 20–24 years and 25–29 years (Figures 39 and 41, Table 34). Rates for men are now highest in those aged 20–24 years, and the rates decrease with age. These data indicate a major shift since 2006, when the highest rates were in men aged 35–39 years. Rates among women decreased in all age groups in 2010 (except for women aged 55 years and older), with the largest decrease in women aged 40–44 years. Rates remained highest among women aged 20–24 years (Figures 39 and 40).

P&S Syphilis by Race/Ethnicity

During 2009–2010, the rate of P&S syphilis increased 9.5% among Hispanics (from 4.2 to 4.6 cases per 100,000 population), 8.7% among American Indians/Alaska Natives (from 2.3 to 2.5 cases per 100,000 population), and 5.0% among non-Hispanic whites (from 2.0 to 2.1 cases per 100,000 population) (Figure 42). The rate decreased 8.7% among non-Hispanic blacks (from 18.4 to 16.8 cases per 100,000 population) and 13.3% among Asian/Pacific Islanders (from 1.5 to 1.3 cases per 100,000 population).

P&S Syphilis by Sex and Sex Behavior

The male-to-female ratio for P&S syphilis rates has risen steadily since 1996, when it was 1.2, reflecting higher rates in men than women (Figure 35). This increase supports analyses of case report data showing increases in P&S syphilis among MSM during 2005–2008.¹⁰ In 2008, this ratio decreased to 5.0, but increased to 5.6 in 2009, and 7.2 in 2010.

In 2005, CDC began collecting information on the sex partners of patients with P&S syphilis. In 2010, this information was available for 82% of male cases.

In 2010, among men who have sex with women only (MSW) with P&S syphilis, 35.8% had primary syphilis, and 64.2% had secondary syphilis. Among women with P&S syphilis, 16.0% had primary syphilis, and 84.0% had secondary syphilis. Among MSM, 25.0% had primary syphilis, and 75.0% had secondary syphilis (Figure 43).

Among women with P&S syphilis, 16.8% were white, 72.8% were black, 6.6% were Hispanic, and 1.6% were of other races/ethnicities. Among MSW, 14.8% were white, 67.0% were black, 13.8% were Hispanic, and 2.5% were of other races/ethnicities. Among MSM, 38.1% were white, 37.0% were black, 19.8% were Hispanic, and 3.1% were of other races/ethnicities (Figure 44).

P&S Syphilis by Race/Ethnicity and Sex

In 2010, rates of P&S syphilis among men were highest among non-Hispanic black men (28.2 cases per 100,000 population), followed by Hispanic (8.5 cases per 100,000 population), American Indians/Alaska Natives (4.3 cases per 100,000 population), non-Hispanic white (4.0 cases per 100,000 population), and Asian/Pacific Islander (2.6 per 100,000 population) men (Figure S).

In 2010, rates of P&S syphilis among women were highest among non-Hispanic black women (6.4 per 100,000 population), followed by American Indians/Alaska Natives (0.7 cases per 100,000 population), Hispanic (0.5 cases per 100,000 population), non-Hispanic white (0.3 cases per 100,000 population), and Asian/Pacific Islander (0.1 per 100,000 population) women (Figure S).

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

In 2010, the rate of P&S syphilis among non-Hispanic blacks was highest among women aged 20–24 years (23.2 cases per 100,000 women) and among men aged 20–24 years (92.5 cases per 100,000 men) and 25–29 years (74.8 cases). For non-Hispanic whites, the rate was highest among women aged 20–24 years (0.9 cases) and among men aged 40–44 years (9.1 cases).

For Hispanics, the rate was highest among women aged 20–24 years (1.8 cases per 100,000 women) and among men aged 20–24 years (19.8 cases per 100,000 men). For Asians/Pacific Islanders, the rate was highest among women aged 20–24 years (1.2 cases) and among men aged 20–24 years (6.5 cases). For American Indians/Alaska Natives, the rate was highest among women aged 30–34 years and 35–39 years (2.4 cases for both) and among men aged 20–24 years (15.6 cases) (Table 35B).

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. During 1998–2010, the proportion of cases reported from sources other than STD clinics increased from 39.2% to 68.1% (Figure 45, Table A2). During 2001–2010, the number of cases among males reported from non-STD clinic sources increased sharply, while the number reported from STD clinics increased only slightly (Figure 45).

During 2010, patients with P&S syphilis usually sought care from private physicians or STD clinics. More cases of syphilis among MSM were reported from private physicians (33.5%) than STD clinics (30.3%) (Figure 46). More cases among women and MSW were reported from STD clinics than from private physicians.

Congenital Syphilis—United States

After an 18% increase in the rate of congenital syphilis during 2006–2008, the rate of congenital syphilis decreased during 2009–2010 (from 9.9 to 8.7 cases per 100,000 live births) (Table 41). In 2010, a total of 377 cases were reported, a decrease from 429 cases in 2009 and 446 cases in 2008. This recent decrease in the rate of congenital syphilis is associated with the decrease in the rate of P&S syphilis among women that has occurred since 2008 (Figure 47).¹¹

In 2010, a total of 28 states, the District of Columbia, and 1 outlying area had 1 or more cases of congenital syphilis (Tables 40 and 41).

In 2009, a total of 33 states and 1 outlying area had 1 or more cases of congenital syphilis (Tables 41).

Syphilis Among Special Populations

More information about syphilis and congenital syphilis in racial and ethnic minority populations, adolescents, MSM, and other populations at higher risk can be found in the Special Focus Profiles.

Syphilis Summary

In recent years, younger men and MSM have accounted for an increasing number of syphilis cases in the United States.⁹ According to information reported in 44 states and the District of Columbia, 67% of P&S syphilis cases are among MSM. Although the majority of U.S. syphilis cases have occurred among MSM, syphilis among MSW continues to be a problem.¹²

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: U.S. Department of Health and Human Services; 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 Morb Mortal Wkly Rep. 1999;48:773-7.

4 Centers for Disease Control and Prevention. Outbreak of syphilis among men who have sex with men — Southern California, 2000. MMWR Morb Mortal Wkly Rep. 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 Morb Mortal Wkly Rep. 2002;51:853-6.

6 Chen SY, Gibson S, Katz MH, Klausner JD, Dilley JW, Schwarcz SK, et al. 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 Morb Mortal Wkly Rep. 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;97:1076-83.

10 Su JR, Beltrami JF, Zaidi AA, Weinstock HS. Primary and secondary syphilis among black and Hispanic men who have sex with men: case report data from 27 States. Ann Intern Med. 2011;155(3):145-51.

11 Centers for Disease Control and Prevention. Congenital syphilis — United States, 2003–2008. MMWR Morb Mortal Wkly Rep. 2010;59:413-7.

12 Centers for Disease Control and Prevention. Primary and secondary syphilis — Jefferson County, Alabama, 2002–2007. MMWR Morb Mortal Wkly Rep. 2009;58:463-7.