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 29). 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 the Surgeon General 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 and remaining unchanged during 2011. During 2012, rates again increased (to 5.0 cases per 100,000 population). Overall increases in rates were observed primarily among men (increasing from 8.1 cases (in 2011) to 9.3 cases (in 2012) per 100,000 population). 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 0.9 cases per 100,000 population in 2011 and 2012.

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 2012 was available for 82%. In 2012, 49 states and the District of Columbia provided information about sex of sex partners. Among cases of P&S syphilis for whom sex of partner was known, MSM accounted for 75% of P&S syphilis cases.

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

During 2011–2012, the number of cases of early latent syphilis reported to CDC increased 10.4% (from 13,136 cases to 14,503 cases), and the number of cases of late and late latent syphilis increased 4.5% (from 18,576 cases to 19,411 cases) (Tables 1, 37, and 39). The total number of cases of syphilis (P&S, early latent, late, late latent, and congenital) reported to CDC increased 8.4% (from 46,040 cases to 49,903 cases) during 2011–2012 (Table 1).

P&S Syphilis—United States

P&S syphilis cases reported to CDC increased from 13,970 in 2011 to 15,667 in 2012, an increase of 12.1%. The rate of P&S syphilis in the United States increased from 4.5 to 5.0 (an 11.1% increase) during 2011– 2012 (Table 1).

P&S Syphilis by Region

The South accounted for 43.5% of P&S syphilis cases in 2012 and 44.1% in 2011. During 2011–2012, rates increased 11.3% in the South (from 5.3 to 5.9 cases per 100,000 population), 15.8% in the Northeast (from 3.8 to 4.4 cases), 3.1% in the Midwest (from 3.2 to 3.3 cases), and 18.4% in the West (from 4.9 to 5.8 cases) (Figure 33, Table 27).

P&S Syphilis by State

In 2012, the 15 states and areas (including the District of Columbia) with the highest rates of P&S syphilis accounted for 70% of all U.S. cases of P&S syphilis. The rate of P&S syphilis in 11 of these 15 states and areas (including the District of Columbia) exceeded the national rate of 5.0 cases per 100,000 population; 9 of these 15 states and areas (including the District of Columbia) were in the South (Figure 33, Table 26).

P&S Syphilis by Metropolitan Statistical Area

The rate of P&S syphilis in 2012 for the 50 most populous MSAs (7.2 cases per 100,000 population) (Table 30) exceeded the overall rate for the United States (5.0 cases) (Table 27). The rate increased in 31 of these 50 MSAs (62%) during 2011–2012.

P&S Syphilis by County

In 2012, 2,123 of 3,142 counties (67.6%) in the United States reported no cases of P&S syphilis, compared with 2,154 counties (68.5%) in 2011 (Figure 34). In 2012, half of the total number of P&S syphilis cases was reported from 26 counties and two cities (Table 33).

P&S Syphilis by Sex

The rate of P&S syphilis increased 14.8% among men (from 8.1 to 9.3 cases per 100,000 men) during 2011–2012 (Figure 31, Table 29). During this same period, the rate among women remained unchanged (0.9 cases per 100,000 women) (Figure 31, Table 28).

P&S Syphilis by Age Group

In 2012, the rate of P&S syphilis was highest among persons aged 20–24 years and 25–29 years (14.8 and 13.7 cases per 100,000 population, respectively) (Table 35).

Rates were highest among men 20–29 years, increasing 11.0% (from 22.8 to 25.3 cases) among men 20–24 years and 15.6% (from 21.2 to 24.5 cases) among men 25–29 years during 2012 (Figures 35 and 37, Table 35). This marks the fifth consecutive year that rates of P&S syphilis among men have been highest among men aged 20–29 years (Table 35). During this time period (2008–2012), rates have increased among men aged 20–24 years by 46.2% (from 17.3 to 25.3 cases) and among men aged 25–29 years by 45.0% (from 16.9 to 24.5 cases). These data indicate a shift since 2006, when the highest rates were in men aged 35–39 years.

Rates increased among women aged 20–24 years and 45–54 years (from 3.7 to 3.9 and from 0.5 to 0.6 cases per 100,000 population, respectively). Rates remained the same or decreased for women of all other age groups. Rates remained highest among women aged 20–24 years (Figures 35 and 36, Table 35).

P&S Syphilis by Race/Ethnicity

In 2012, among the 48 jurisdictions (47 states and the District of Columbia) that submitted data in the new race and ethnic categories according to the revised Office of Management and Budget (OMB) standards, rates of P&S syphilis remained highest among blacks (16.4 cases per 100,000 population) (Table 36B). The rate among blacks was 6.1 times the rate among whites (2.7 cases per 100,000 population). The rate among American Indians/Alaska Natives (2.9) was 1.1 times that of whites, the rate among Native Hawaiians/Other Pacific Islanders (8.4) was 3.1 times that of whites, the rate among Hispanics (5.7) was 2.1 times that of whites, and the rate among Asians (2.0) was 0.7 times that of whites (Table 36B).

During 2008–2012, among the 39 jurisdictions (38 states and the District of Columbia) that submitted data in the new race and ethnic categories for all five years during that period, the rate of P&S syphilis increased 40.9% among Hispanics (from 4.2 to 5.9 cases per 100,000 population), 21.4% among non-Hispanic whites (from 2.4 to 2.9 cases per 100,000 population), 17.8% among American Indians/Alaska Natives (from 2.9 to 3.4 cases per 100,000 population), 55.6% among Asians (from 1.4 to 2.1 cases per 100,000 population), 57.6% among Native Hawaiian or Other Pacific Islanders (from 5.4 to 8.5 cases per 100,000 population), and 188.9% among Multirace individuals (from 0.7 to 1.9 cases per 100,000 population) (Figure 38). The rate decreased 0.7% among non- Hispanic blacks (from 17.1 to 16.9 cases per 100,000 population). Non-Hispanic blacks, non-Hispanic whites, and Hispanics comprised 94.5% of reported cases in 2008 and 93.8% of reported cases in 2012.

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), and again during 2008–2012 (from 5.0 to 10.3), reflecting higher rates in men than women (Figure 31). In 2012, this ratio was almost double the ratio of 2003, and almost seven times the ratio of 2000.

In 2005, CDC began collecting information on the sex partners of patients with P&S syphilis. In 2012, this information was available for 82% of male cases. During 2007–2012, 33 areas reported sex of partner data for at least 70% of cases each year during this time period (Figure 30). During 2007–2008 in these areas, increases in cases occurred among women, men having sex with women only (MSW), and MSM. During 2008–2012 in these areas, cases among women and MSW declined 24% (from 1,364 to 1,034 cases) and 15% (from 1,884 to 1,600 cases), respectively, while cases among MSM increased 46% (from 5,872 to 8,553 cases). During 2011–2012 in these areas, cases increased very slightly among MSW (4%) and women (1%), while cases among MSM increased 15% (from 7,422 cases in 2011 to 8,553 cases in 2012)—a larger increase than in previous years. (In these areas, cases among MSM increased 6% during 2008–2009 (from 5,872 to 6,243), 10% during 2009–2010 (from 6,243 to 6,870 cases), and 8% during 2010–2011 (from 6,870 to 7,422 cases).) In 2012, among MSW with P&S syphilis, 39.2% had primary syphilis, and 60.8% had secondary syphilis. Among women with P&S syphilis, 18.6% had primary syphilis, and 81.4% had secondary syphilis. Among MSM, 27.2% had primary syphilis, and 72.8% had secondary syphilis (Figure 39).Among women with P&S syphilis, 18.1% were white, 65.2% were black, 13.2% were Hispanic, and 2.5% were of other races/ethnicities. Among MSW, 20.4% were white, 55.9% were black, 19.2% were Hispanic, and 2.8% were of other races/ethnicities. Among MSM, 37.9% were white, 34.4% were black, 21.1% were Hispanic, and 4.5% were of other races/ethnicities (Figure 40).

P&S Syphilis by Race/Ethnicity and Sex

In 2012, among the 48 jurisdictions (47 states and the District of Columbia) that submitted data in the new race and ethnic categories according to OMB standards, rates of P&S syphilis among men were highest among non-Hispanic black men (28.9 cases per 100,000 population), followed by Native Hawaiian or Other Pacific Islander (14.9 cases per 100,000 population), Hispanic (10.4 cases per 100,000 population), American Indians/Alaska Natives (5.3 cases per 100,000 population), non-Hispanic white (5.1 cases per 100,000 population), Asian (4.0 cases per 100,000 population) and Multirace (3.8 cases per 100,000 population) men (Figure P, Table 36B).

In 2012, among the 48 jurisdictions (47 states and the District of Columbia) that submitted data in the new race and ethnic categories according to OMB standards, rates of P&S syphilis among women were highest among non-Hispanic black women (4.9 cases per 100,000 population), followed by Native Hawaiian or Other Pacific Islander (1.6 cases per 100,000 population), Hispanic (0.8 cases per 100,000 population), American Indian/Alaska Native (0.7 cases per 100,000 population), non-Hispanic white (0.3 cases per 100,000 population), Multirace (0.2 cases per 100,000 population) and Asian (0.1 cases per 100,000 population) women (Figure P, Table 36B).

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

In 2012, among the 48 jurisdictions (47 states and the District of Columbia) that submitted data in the new race and ethnic categories according to OMB standards, the rate of P&S syphilis among non- Hispanic blacks remained highest among women aged 20–24 years (19.1 cases per 100,000 women) and among men aged 20–24 years and 25–29 years (96.7 and 89.2 cases per 100,000 men, respectively). For Hispanics, the rate was highest among women aged 20–24 years and 25–29 years (2.1 and 2.0 cases per 100,000 women, respectively), and among men aged 20–24 years and 25–29 years (24.3 and 23.2 cases per 100,000 men, respectively). For non-Hispanic whites, the rate was highest among women aged 20–24 years (1.1 cases per 100,000 women) and among men aged 25–29 years and 30–34 years (10.8 cases per 100,000 men for both groups) (Table 36B).

For Asians, the rate was highest among women aged 15–19 years and 20–24 years (0.8 cases per 100,000 women for both groups) and among men aged 25–29 years (10.3 cases per 100,000 men). For American Indians/Alaska Natives, the rate was highest among women aged 20–24 years (3.5 cases per 100,000 women) and among men aged 20–24 years (17.9 cases per 100,000 men). For Native Hawaiian or Other Pacific Islanders, the rate was highest among women aged 20–24 years (9.0 cases per 100,000 women) and among men aged 25–29 years (34.8 cases per 100,000 men). For Multirace individuals, rates were highest among women aged 35–39 years (1.5 cases per 100,000 women) and among men aged 30–34 years (11.7 cases per 100,000 men) (Table 36B).

In some age groups, particularly young men aged 20–24 years and 25–29 years, wide disparities in rates of P&S syphilis have occurred in recent years.^9,10 During 2007–2011, rates among black men aged 20–24 years increased from 54.9 to 96.2 cases per 100,000 population (75%). In 2012, rates among men aged 20–24 years and 25–29 years remained highest among blacks (96.7 cases and 89.2 cases per 100,000 population, respectively). These rates were 10.6 and 8.3 times (respectively) the rate of white men of the same age groups. The 2012 rate among Hispanic men aged 20–24 years is almost double the 2007 rate (24.3 versus 14.4 cases per 100,000 population, respectively), and is 2.7 times the rate of white men aged 20–24 years (9.1 cases per 100,000 population).

These disparities in syphilis rates among young men are of particular concern given data indicating increasing HIV incidence among young men.^11,12

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 1998–2012, the proportion of cases reported from sources other than STD clinics increased from 39.2% to 68.1% (Figure 41, Table A2). During 2003–2012, the number of cases among males reported from non-STD clinic sources increased steadily, while the number reported from STD clinics increased slightly by comparison (Figure 41).

In 2012, 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 42).

Congenital Syphilis—United States

After an 18% increase in the rate of congenital syphilis during 2006–2008, the rate of congenital syphilis decreased 25% during 2009–2012 (from 10.4 to 7.8 cases per 100,000 live births) (Table 42). In 2012, a total of 322 cases were reported, a decrease from 358 cases in 2011, 387 cases in 2010, and 431 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 43). The 2012 rate of congenital syphilis (7.8 cases per 100,000 live births) marks the lowest rate of congenital syphilis recorded since 1988, when the case definition was changed.

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 proportion of syphilis cases in the United States.^{9, 10} According to information reported from 49 states and the District of Columbia, 75% of P&S syphilis cases are among MSM. Although the majority of U.S. syphilis cases have occurred among MSM, transmission among MSW and women continues to occur in certain jurisdictions.

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. Trends in HIV/AIDS diagnoses among men who have sex with men — 33 States, 2000– 2006. MMWR Morb Mortal Wkly Rep. 2008; 57:681–686.

12 Brewer TH, Schillinger J, Lewis FM, Blank S, Pathela P, Jordahl L, et al. Infectious syphilis among adolescent and young adult men: implications for human immunodeficiency virus transmission and public health interventions. Sex Transm Dis. 2011 May;38(5):367-71