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 36). 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. The 2011 rate remained unchanged. Overall increases in rates were observed primarily among men (increasing from 3.0 cases per 100,000 population in 2001 to 8.2 cases in 2011). 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 and 1.0 cases per 100,000 population in 2011.

Syphilis remains a major health problem with increases persisting among men who have sex with men (MSM). Cases among MSM 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 2011 was available for 83%. In 2011, 72% of P&S syphilis cases in 46 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 2010–2011, the number of cases of early latent syphilis reported to CDC decreased 3.4% (from 13,604 cases to 13,136), and the number of cases of late and late latent syphilis increased 2.7% (from 18,079 cases to 18,576) (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 0.4% (from 45,844 cases to 46,042) during 2010–2011 (Table 1).

P&S Syphilis—United States

P&S syphilis cases reported to CDC increased from 13,774 in 2010 to 13,970 in 2011, an increase of 1.4%. The rate of P&S syphilis in the United States in 2011 (4.5 cases per 100,000 population) remained unchanged from the rate in 2010 (Figure 36, Table 1).

P&S Syphilis by Region

The South accounted for 44.1% of P&S syphilis cases in 2011 and 45.5% in 2010. During 2010–2011, rates decreased 1.8% in the South (from 5.5 to 5.4 cases per 100,000 population), 5.0% in the Northeast (from 4.0 to 3.8 cases), and 5.9% in the Midwest (from 3.4 to 3.2 cases), and increased 14.0% in the West (from 4.3 to 4.9 cases) (Figure 40, Table 26).

P&S Syphilis by State

In 2011, the 15 states and areas (including the District of Columbia) with the highest rates of P&S syphilis accounted for 71% of all U.S. cases of P&S syphilis. The rate of P&S syphilis in all of these 15 states and areas (including the District of Columbia) exceeded the national rate of 4.5 cases per 100,000 population; 10 of these 15 states and areas (including the District of Columbia) were in the South (Figure 40, Table 25).

P&S Syphilis by Metropolitan Statistical Area

The rate of P&S syphilis in 2011 for the 50 most populous MSAs (6.4 cases per 100,000 population) (Table 29) exceeded the overall rate for the United States (4.5 cases) (Table 26). The rate increased in 27 of these 50 MSAs (54%) during 2010–2011.

P&S Syphilis by County

In 2011, 2,154 of 3,142 counties (68.5%) in the United States reported no cases of P&S syphilis, compared with 2,167 counties (69.0%) in 2010 (Figure 41). In 2011, half of the total number of P&S syphilis cases was reported from 26 counties and two cities (Table 32).

P&S Syphilis by Sex

The rate of P&S syphilis increased 3.8% among men (from 7.9 to 8.2 cases per 100,000 men) during 2010–2011 (Figure 38, Table 28). During this same period, the rate decreased 9.1% among women (from 1.1 to 1.0 cases per 100,000 women) (Figure 38, Table 27).

P&S Syphilis by Age

In 2011, the rate of P&S syphilis was highest among persons aged 20–24 years and 25–29 years (13.8 and 12.1 cases per 100,000 population, respectively) (Table 34).

Rates were highest among men 20–29 years, increasing 5.9% (from 22.1 to 23.4 cases) among men 20–24 years and 7.0% (from 20.0 to 21.4 cases) among men 25–29 years during 2011 (Figures 42 and 44, Table 34). This marks the fourth consecutive year that rates of P&S syphilis among men have been highest among men aged 20–29 years (Table 34).These data indicate a shift since 2006, when the highest rates were in men aged 35–39 years.

Rates among women decreased in all age groups during 2010–2011 (except for women aged 10–14 and 55 years and older), with the largest decrease in women aged 45–54 years. Rates remained highest among women aged 20–24 years (Figures 42 and 43, Table 34).

P&S Syphilis by Race/Ethnicity

During 2010–2011, the rate of P&S syphilis increased 4.5% among Hispanics (from 4.4 to 4.6 cases per 100,000 population), 8.0% among American Indians/Alaska Natives (from 2.5 to 2.7 cases per 100,000 population), 9.5% among non-Hispanic whites (from 2.1 to 2.3 cases per 100,000 population), and 33.3% among Asian/Pacific Islanders (from 1.2 to 1.6 cases per 100,000 population) (Figure 45). The rate decreased 6.6% among non-Hispanic blacks (from 16.6 to 15.5 cases per 100,000 population)

P&S Syphilis by Sex and Sex Behavior

The male-to-female rate ratio for P&S syphilis rates rose steeply during 2000–2003 (from 1.5 to 5.3), reflecting higher rates in men than women (Figure 38). This ratio has since increased more gradually to 8.2 in 2011.

In 2005, CDC began collecting information on the sex partners of patients with P&S syphilis. In 2011, this information was available for 83% of male cases. During 2007–2011, 33 areas reported sex of partner data for at least 70% of cases each year during this time period. In these areas, cases among women and men having sex with women only (MSW) have declined since 2008, while cases among MSM have increased each consecutive year (Figure 37).

In 2011, among MSW with P&S syphilis, 40.1% had primary syphilis, and 59.9% had secondary syphilis. Among women with P&S syphilis, 18.9% had primary syphilis, and 81.1% had secondary syphilis. Among MSM, 26.3% had primary syphilis, and 73.7% had secondary syphilis (Figure 46).

Among women with P&S syphilis, 17.4% were white, 69.4% were black, 9.5% were Hispanic, and 2.0% were of other races/ethnicities. Among MSW, 18.9% were white, 61.8% were black, 14.6% were Hispanic, and 2.5% were of other races/ethnicities. Among MSM, 38.7% were white, 35.7% were black, 18.8% were Hispanic, and 4.4% were of other races/ethnicities (Figure 47).

P&S Syphilis by Race/Ethnicity and Sex

In 2011, rates of P&S syphilis among men were highest among non-Hispanic black men (27.0 cases per 100,000 population), followed by Hispanic (8.5 cases per 100,000 population), American Indians/Alaska Natives (5.0 cases per 100,000 population), non-Hispanic white (4.4 cases per 100,000 population), and Asian/Pacific Islander (3.1 cases per 100,000 population) men (Figure S, Table 35B).

In 2011, rates of P&S syphilis among women were highest among non-Hispanic black women (5.0 cases per 100,000 population), followed by Hispanic (0.6 cases per 100,000 population), American Indian/Alaska Native (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, Table 35B).

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

In 2011 the rate of P&S syphilis among non-Hispanic blacks was highest among women aged 20–24 years (18.9 cases per 100,000 women) and among men aged 20–24 years (96.2 cases per 100,000 men) and 25–29 years (82.5 cases). For non-Hispanic whites, the rate was highest among women aged 20–24 years and 25–29 years (0.9 cases for both) and among men aged 25–29 years (9.5 cases) and 40–44 years (9.6 cases) (Table 35B).

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 and 25–29 years (18.8 cases per 100,000 men for both). For Asians/Pacific Islanders, the rate was highest among women aged 20–24 years (0.5 cases) and among men aged 30–34 years (7.3 cases). For American Indians/Alaska Natives, the rate was highest among women aged 25–29 years (2.1 cases) and among men aged 20–24 years (13.5 cases) and 30–34 years (13.3 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 1998–2011, the proportion of cases reported from sources other than STD clinics increased from 39.2% to 72.0% (Figure 48, Table A2). During 2002–2011, 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 48).

During 2011, patients with P&S syphilis usually sought care from private physicians or STD clinics. Similar proportions of cases among women and MSM were reported from private physicians and STD clinics, while substantially more cases among MSW were reported from STD clinics than from private physicians (Figure 49).

Congenital Syphilis—United States

After an 18% increase in the rate of congenital syphilis during 2006–2008, the rate of congenital syphilis decreased during 2008–2011 (from 10.5 to 8.5 cases per 100,000 live births) (Table 41). In 2011, a total of 360 cases were reported, a decrease from 387 cases in 2010 and 429 cases in 2009. 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 50).

In 2011, a total of 23 states, the District of Columbia, and 1 outlying area had 1 or more cases of congenital syphilis (Table 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, young MSM have accounted for an increasing number of syphilis cases in the United States.^{9, 10} According to information reported from 46 states and the District of Columbia, 72% of P&S syphilis cases are among MSM. Although the majority of U.S. syphilis cases have occurred among MSM, syphilis among MSW and women continues to be a problem. ¹¹

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.