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 primary and secondary (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 28). 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 CDCs 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 2007. Overall increases in rates between 2001 and 2007 were observed primarily among men (from 3.0 cases per 100,000 population to 6.6 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 0.9 cases per 100,000 population in 2005 to 1.0 case per 100,000 population in 2006, to 1.1 case per 100,000 population in 2007.

Syphilis remains an important problem in the South and in urban areas in other regions of the country. Increases in cases among MSM have occurred and have been characterized by high rates of HIV co-infection and high-risk sexual behavior.^3-7 The estimated proportion of P&S syphilis cases attributable to MSM increased from 4% in 2000 to 62% in 2004. In 2005, CDC requested that all state health departments report sex of sex partners for persons with syphilis. In 2007, 65% 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 2007 was available for 79%.

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

Between 2006 and 2007, the number of cases of early latent syphilis reported to CDC increased 17.2% (from 9,186 to 10,768), while the number of cases of late and late latent syphilis increased 3.5% (from 17,644 to 18,256) (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 10.7% (from 36, 959 to 40, 920) between 2006 and 2007 (Table 1).

P&S Syphilis — United States

In 2007, P&S syphilis cases reported to CDC increased to 11,466 from 9,756 in 2006, an increase of 17.5%. The rate of P&S syphilis in the United States in 2007 (3.8 cases per 100,000 population) was 15.2% higher than the rate in 2006 (3.3 cases per 100,000 population), and it is greater than the HP 2010 target of 0.2 case per 100,000 population (Figure 29, Table 1).¹⁰

P&S Syphilis by Region

The South accounted for 48.8% of the P&S syphilis cases in 2007 and 47.1% in 2006. Between 2006 and 2007, rates increased 21.4% in the South (from 4.2 to 5.1 cases per 100,000 population), 30.8% in the Northeast (from 2.6 to 3.4), 8.1% in the West (from 3.7 to 4.0) and 5.6% in the Midwest (from 1.8 to 1.9). The 2007 rates in all regions were greater than the HP 2010 target of 0.2 cases per 100,000 population (Figure 30, Table 25).

P&S Syphilis by State

In 2007, 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 31, Table 24). Four states and one outlying area reported five or fewer cases of P&S syphilis in 2007 (Table 24).

P&S Syphilis by Metropolitan Statistical Area (MSA)

The rate of P&S syphilis in 2007 for the 50 most populous MSAs (5.7) exceeded the HP 2010 target of 0.2 cases per 100,000 population (Table 28).

P&S Syphilis by County

In 2007, 2,275 of 3,140 counties (72.4%) in the United States reported no cases of P&S syphilis compared with 2,360 (75.2%) in 2006. Of 865 counties reporting at least one case of P&S syphilis in 2007, five (0.6%) 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 860 counties in 2007 (Figure 32). These 860 counties (27.4% of the total number of counties in the United States) accounted for 99.9% of the total P&S syphilis cases reported in 2007. In 2007, half of the total number of P&S syphilis cases were reported from 23 counties and two cities (Table 31).

P&S Syphilis by Sex

The rate of P&S syphilis increased 17.9% among men (from 5.6 cases to 6.6 cases per 100,000 men) between 2006 and 2007 (Figure 29, Table 27). During this time, the rate increased 10.0% among women from 1.0 to 1.1 cases per 100,000 women (Figure 29, Table 26).

P&S Syphilis by Age

In 2007, the rate of P&S syphilis was highest in persons in the 25- to 29-year-old age group (8.9 cases per 100,000 population) (Figure 33 and Table 32).

Between 2006 and 2007, P&S syphilis rates in most age groups among men and women increased (Table 32 and Figures 34 and 35).

P&S Syphilis by Race/Ethnicity

From 2006 to 2007, the rate of P&S syphilis increased in all racial and ethnic groups except Asian/Pacific Islanders (Figure 36). The rate increased 5.3% among non-Hispanic whites (from 1.9 to 2.0), 25% among blacks (from 11.2 to 14.0), 22.9% among Hispanics (from 3.5 to 4.3), and 6.3% among American Indian/Alaska Natives (from 3.2 to 3.4).  The rate remained the same at 1.2 cases per 100,000 population among Asian/Pacific Islanders (Table 33B).

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, suggesting an increase among MSM. In 2007, the rate of P&S syphilis in males was 6.0 times that in females, an increase from 5.7 in 2006.

In 2005, CDC began collecting information on the sexual orientation of patients with P&S syphilis. In 2007, this information was available for 79% of male cases.

In 2007, the stage of disease was reported as follows: among heterosexual men with P&S syphilis, 43.0% had primary syphilis and 57% had secondary syphilis. Among female patients, 17.9% had primary syphilis and 82.1% had secondary syphilis. Among men who had sex with men with P&S syphilis, 24.3% had primary syphilis and 75.7% had secondary syphilis (Figure 37).

Of females with P&S syphilis, 21.9% were white, 63.5% were black, 9.6% were Hispanic, and 5.0% were of other races/ethnicities. Of heterosexual men, 19.3% were white, 59.8% were black, 16.1% were Hispanic, and 4.8% were of other race/ethnicities. Of men who had sex with men, 40.8% were white, 33.2% were black, 19.3% were Hispanic, and 6.7% were of other races/ethnicities (Figure 38).

P&S Syphilis by Race/Ethnicity and Sex

From 2006 to 2007, the P&S syphilis rate among non-Hispanic white males increased 5.7% (from 3.5 to 3.7), and increased among non-Hispanic white females as well (from 0.3 to 0.4). The rate increased 28.2% among black males (from 18.1 to 23.2) and 14.3% among black females (from 4.9 to 5.6). The rate increased 25.0% among Hispanic males (from 6.0 to 7.5), but remained unchanged among Hispanic females (0.8). The rate remained unchanged for both Asian/Pacific Island males (2.4), and Asian/Pacific Island females (0.1). The rate increased 36.8% among American Indian/Alaska Native females (from 1.9 to 2.6), but decreased 8.5% among American Indian/Alaska Native males (from 4.7 to 4.3) (Table 33B).

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

In 2007, the rate of P&S syphilis among blacks was highest among women aged 20 to 24 years (16.0) and among men aged 20 to 24 years (57.5) and 25 to 29 years (57.4). For non-Hispanic whites, the rate was highest among women aged 20 to 24 years (1.1) and among men aged 40 to 44 years (10.4). For Hispanics, the rate was highest among women aged 20 to 24 years (2.3) and among men aged 40 to 44 years (15.5). For Asian/Pacific Islanders, the rate was highest among women aged 20 to 24 years and 30 to 34 years (both 0.4) and among men aged 25 to 29 years (5.8). For American Indian/Alaska Natives, the rate was highest among women aged 25 to 29 years (7.8) and among men aged 30 to 34 years (18.2) (Table 33B).

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 2007, the proportion of P&S syphilis cases reported from sources other than STD clinics increased from 39.2% to 68.7% (Figure 39 and Table A2). Between 2001 and 2007, the number of cases among males reported from non-STD clinic sources increased sharply while the number from STD clinics increased slightly (Figure 39).

During 2007, patients with P&S syphilis primarily sought care with private physicians or STD clinics. Men who have sex with men were more frequently reported from private physicians (36.7%) than STD clinics (27.1%) (Figure 40). More cases among women and heterosexual men were reported from STD clinics than private physicians.

Congenital Syphilis — United States

After 14 years of decline in the United States, the rate of congenital syphilis increased 15.4% between 2006 and 2007 (from 9.1 to 10.5 cases per 100,000 live births) (Table 39). In 2007, 430 cases were reported, an increase from 373 in 2006. This increase in the rate of congenital syphilis may relate to the increase in the rate of P&S syphilis among women that has occurred in recent years (Figure 41).

Congenital Syphilis by State

In 2007, 29 states, the District of Columbia, and two outlying area had rates of congenital syphilis that exceeded the HP 2010 target of one case per 100,000 live births (Tables 38 and 39).

Syphilis Among Special Populations

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

Syphilis Summary

In recent years, MSM have accounted for an increasing number of estimated syphilis cases in the United States⁹ and now account for 65% of syphilis cases in the United States based on information from 44 states and Washington, D.C. Despite the majority of U.S. syphilis cases occurring among MSM, syphilis cases among heterosexuals is an emerging problem given the recent increases among women and infants.

 

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 CDC. 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. Sexually Transmitted Diseases 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 U.S. Department of Health and Human Services. Healthy People 2010. 2nd ed. With Understanding and Improving Health and Objectives for Improving Health. 2 vols. Washington, DC: U.S. Government Printing Office, November 2000.