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 over 70% 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 26). 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 Collaboration with diverse organizations, public health professionals, the private medical community, and other partners working in the fields of STD and HIV is essential for the successful elimination of syphilis in the United States.3
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 from 2001 to 2005. Overall increases in rates between 2001 and 2005 were observed primarily among men. In 2005, for the first time in over 10 years, the rate of primary and secondary syphilis among women increased from 0.8 cases per 100,000 population in 2003 and 2004 to 0.9 cases per 100,000 population.
Despite national progress toward syphilis elimination, syphilis remains an important problem in the South and in urban areas in other regions of the country. Increases among men who have sex with men have occurred at least since 2000 and continue through 2005. These men have been characterized by high rates of HIV co-infection and high-risk sexual behavior.4-11
Syphilis – All Stages (P&S, Early Latent, Late, Late Latent, Congenital)
Between 2004 and 2005, the number of cases of early latent syphilis reported to CDC increased 5.3% (from 7,768 to 8,176), while the number of cases of late and late latent syphilis decreased 7.2% (from 17,300 to 16,049) (Table 1). The total number of cases of syphilis (all stages: P&S, early latent, late, late latent, and congenital syphilis) reported to CDC decreased 0.4% (from 33,419 to 33,278) between 2004 and 2005 (Table 1).
P&S Syphilis – United States
In 2005, P&S syphilis cases reported to CDC increased to 8,724 from 7,980 in 2004, an increase of 9.3%. The rate of P&S syphilis in the United States in 2005 (3.0 cases per 100,000 population) was 11.1% higher than the rate in 2004 (2.7 cases per 100,000 population), and it is greater than the HP 2010 target of 0.2 case per 100,000 population (Figure 26, Table 1).12 Between 2004 and 2005, P&S syphilis rates in most age groups increased. (Table 31).
P&S Syphilis by Region
The South accounted for 46.4% of P&S syphilis in 2005 and 47.5% in 2004. Between 2004 and 2005, rates increased in all U.S. regions; rates increased 5.6% in the South (from 3.6 to 3.8 cases per 100,000 population), 4.5% in the Northeast (from 2.2 to 2.3), 14% in the West (from 2.9 to 3.3); and 13% in the Midwest (from 1.6 to 1.8). The 2005 rates in all regions were greater than the HP 2010 target of 0.2 case per 100,000 population (Figure 28, Table 24).
P&S Syphilis by State
In 2005, P&S syphilis rates in six states and no outlying areas were less than or equal to the HP 2010 target of 0.2 case per 100,000 population (Figure 29, Table 23). Seven states and two outlying areas reported five or fewer cases of P&S syphilis in 2005 (Table 23).
P&S Syphilis by County
In 2005, 2,434 of 3,140 counties (77.5%) in the United States reported no cases of P&S syphilis compared with 2,488 (79.3%) counties reporting no cases in 2004. Of 706 counties reporting at least one case of P&S syphilis in 2005, 5 (0.7%) had rates at or below the HP2010 target of 0.2 case per 100,000 population. Rates of P&S syphilis were above the HP2010 target for 701 counties in 2005 (Figure 30). These 701 counties (22.3% of the total number of counties in the United States) accounted for 99.9% of the total P&S syphilis cases reported in 2005.
In 2005, half of the total number of P&S syphilis cases were reported from 19 counties and two cities (Table 27).
P&S Syphilis by MSA
The rate of P&S syphilis in 2005 for the 50 most populous MSAs (4.5) exceeded the HP 2010 target of 0.2 case per 100,000 population (Table 28).
P&S Syphilis by Reporting Source
Between 1990 and 2005, the proportion of P&S syphilis cases reported from sources other than STD clinics increased from 25.6% to 68.7% (Figure 31, Table A2). Between 2001 and 2005, the number of cases among males reported from non-STD clinic sources increased sharply while the number from STD clinics remained stable (Figure 31).
P&S Syphilis by Sex
The rate of P&S syphilis increased 8.5% among men (from 4.7 cases to 5.1 cases per 100,000 men) between 2004 and 2005 (Figure 27, Table 26). During this time, the rate increased among women from 0.8 to 0.9 cases per 100,000 women (Figure 27, Table 25).
P&S Syphilis by Male to Female Rate Ratio
The male-to-female rate ratio for P&S syphilis has risen steadily since 1996 when it was 1.2 (Figure 33), suggesting an increase in syphilis among MSM during this time. The male-to-female rate ratio in 2005 was 5.7.
Between 2004 and 2005, the male-to-female rate ratio for P&S syphilis increased among whites (from 10 to 11), African Americans (from 3.3 to 3.6) Asian/Pacific Islanders (from 11 to 12), and American Indians/Alaska Natives (from 1.3 to 2.1). The male-to-female rate ratio decreased among Hispanics (from 7.7 to 6.1) (Table 32B).
An increase in the male-to-female rate ratio for P&S syphilis occurred in the District of Columbia, Puerto Rico and in 18 of 33 states (55%) that reported at least 25 cases in 2005.
P&S Syphilis by Race/Ethnicity and Sex
From 2004 to 2005, the rate among non-Hispanic whites increased 12.5% (from 1.6 to 1.8); rates among men increased 10% (from 3.0 to 3.3) and stayed the same among women (0.3). The rate among African Americans increased 11.4% (from 8.8 to 9.8); rates among men increased 12.9% (from 13.9 to 15.7), and rates among women increased 4.8% (from 4.2 to 4.4). The rate among Hispanics increased 6.5% (from 3.1 to 3.3); rates among men increased 1.9% (from 5.4 to 5.5), and rates among women increased 28.6% (from 0.7 to 0.9). The rate among Asian/Pacific Islanders stayed the same (1.2); rates among men increased 4.5% (from 2.2 to 2.3) and stayed the same among women (0.2). The rate among American Indian/Alaska Natives decreased 22.6% (from 3.1 to 2.4); rates among men decreased 5.7% (from 3.5 to 3.3), and rates among women decreased 42.9% (from 2.8 to 1.6) (Figure 32, Table 32B).
In 2005, the rate of P&S syphilis reported among African Americans (9.8 cases per 100,000 population) was 5.4 times higher than the rate among non-Hispanic whites (1.8 cases per 100,000 population), reflecting an overall decrease in disparity during the last several years (Table 32B).
P&S Syphilis by Race/Ethnicity, Age, and Sex
In 2005, the rate of P&S syphilis among African Americans was highest among women aged 20-24 years (13.5) and among men aged 25-29 years (38.2). For non-Hispanic whites, the rate was highest among women aged 20-24 years (0.8) and among men aged 35-39 years (10.3). For Hispanics, the rate was highest among women aged 20-24 years (2.9) and among men aged 35-39 years (14.0). For Asian/Pacific Islanders, the rate was highest among women aged 20-24 years (0.8) and among men aged 30-34 years (6.6). For American Indian/Alaska Natives, the rate was highest among women aged 35-39 years (4.7) and among men aged 30-34 years (11.4) (Table 32B).
Congenital Syphilis – United States
Between 2004 and 2005, the overall rate of congenital syphilis decreased 12.1% in the United States, from 9.1 to 8.0 cases per 100,000 live births (Figure 37, Table 37). The continuing decline in the rate of congenital syphilis (Figure 38) likely reflects the substantial reduction in the rate of P&S syphilis among women that has occurred during the last decade (Figure 37).13,14
Between 1996 and 2005, the average yearly percentage decrease in the congenital syphilis rate was 14.1% (Table 37). The average yearly percentage decrease in the rate of P&S syphilis among women between 1996 and 2005 was 14.1%. Overall, there has been a 74% decrease in cases of congenital syphilis since 1996.
Congenital Syphilis by State
Syphilis Among Special Populations
Additional information about syphilis and congenital syphilis in racial and ethnic minority populations, adolescents, men who have sex with men, and other at risk populations can be found in the Special Focus Profiles.
6 Bronzan R, Echavarria L, Hermida J, Trepka M, Burns T, Fox, K. Syphilis among men who have sex with men (MSM) in Miami – Dade County, Florida [Abstract no. P135]. In: Program and abstracts of the 2002 National STD Prevention Conference, San Diego, California, March 4-7, 2002.
8 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.
9 Ciesielski CA, Boghani S. HIV infection among men with infectious syphilis in Chicago, 1998–2000 [Abstract no. 12]. In: Program and abstracts of the 9th Conference on Retroviruses and Opportunistic Infections, Seattle, Washington, February 24-28, 2002.
11 Robinson BC, Chiliade PA, Lee C, Bautista J, Saenz G. Redirecting elimination efforts in response to the changing epidemiology of syphilis [Abstract no. 167]. In: Program and abstracts of the 2004 National STD Prevention Conference, Philadelphia, Pennsylvania, March 8-11, 2004.
12 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.