Congenital Syphilis --- United States, 2003--2008

Untreated syphilis during pregnancy, especially early syphilis, can lead to stillbirth, neonatal death, or infant disorders such as deafness, neurologic impairment, and bone deformities. Congenital syphilis (CS) can be prevented by early detection of maternal infection and treatment at least 30 days before delivery. Changes in the population incidence of primary and secondary (P&S) syphilis among women usually are followed by similar changes in the incidence of CS. To assess recent trends in CS rates, CDC analyzed national surveillance data from the period 2003--2008. This report summarizes the results of that analysis, which indicated that, after declining for 14 years, the CS rate among infants aged <1 year increased 23%, from 8.2 cases per 100,000 live births in 2005 to 10.1 during 2008. That increase followed a 38% increase in the P&S syphilis rate among females aged ≥10 years from 2004 to 2007. During 2005--2008, CS rates increased primarily in the South (from 9.6 per 100,000 live births to 15.7) and among infants born to black mothers (from 26.6 per 100,000 live births to 34.6). Reversing the upward trend in CS rates will require collaboration among health-care providers, health departments, health insurers, policymakers, and the public to reduce syphilis among women and to increase early prenatal care access and syphilis screening during pregnancy.

Syphilis, including congenital syphilis, is reportable in all 50 states and the District of Columbia (DC). CS case definitions are developed by the Council of State and Territorial Epidemiologists in collaboration with CDC.* CDC analyzed national surveillance data from the period 2003--2008 for CS cases reported to state and local health departments. Case data were reported to CDC through the National Electronic Telecommunication System for Surveillance (NETSS) (with the exception of a few mailed reports). Rates of CS per 100,000 live births were calculated using denominators from U.S. natality data.† P&S syphilis rates among females aged ≥10 years were calculated using denominators from bridged race population estimates for 2000--2007 based on 2000 U.S. Census counts.§

From 2003 to 2005, the number of CS cases reported annually in the United States decreased from 432 to 339; the corresponding national CS incidence rate decreased from 10.6 cases per 100,000 live births in 2003 to 8.2 in 2005. Subsequently, the number of CS cases increased from 339 in 2005 to 431 in 2008, and the CS rate increased 23% from 8.2 per 100,000 live births to 10.1 during the same period. This increase followed a 38% increase in the P&S syphilis rate among females aged ≥10 years, from 0.8 per 100,000 in 2004 to 1.1 in 2007 (Figure). In 2008, the P&S syphilis rate among females continued to increase, to 1.5 per 100,000 (1). Nearly all of the national increase in CS cases from 2005 to 2008 occurred in the South¶ (Table 1), where the number of cases increased from 148 to 253 and the CS rate increased 64%, from 9.6 per 100,000 live births to 15.7. In the Northeast, the number of cases increased from 28 to 37, and the CS rate increased 29%, from 4.2 per 100,000 live births to 5.4.

From 2005 to 2008, most of the increase in CS cases and CS rate occurred among infants born to black mothers. The number of cases in this population increased from 156 in 2005 to 215 in 2008, and the CS rate increased 30%, from 26.6 per 100,000 live births in 2005 to 34.6 in 2008 (Table 1). The increase in rates among infants born to black mothers was observed primarily in the South. In 2005, 79 (51%) of the 156 infants with CS born to black mothers were born in the South; that percentage increased to 75% (162 of 215 infants) in 2008.

From 2005 to 2008, the CS rate among infants born to Hispanic mothers increased 2%, from 12.6 per 100,000 live births to 12.8. The rate among infants born to white mothers increased 115%, from 1.3 per 100,000 live births to 2.8; however, the number of cases was small (31 in 2005 and 65 in 2008). In 2008, infants of black mothers accounted for 50% of CS cases, infants of Hispanic mothers accounted for 31% of cases, and infants of white, Asian/Pacific Islander, and American Indian/Alaskan Native mothers accounted for 15%, 2%, and 1%, respectively.

Of 431 CS cases reported in 2008, mothers of 125 (29%) infants did not receive prenatal care, and syphilis infection was detected at delivery (Table 2). Among 276 CS cases in which the mother received prenatal care, in 75 (27%) cases mothers were first screened for syphilis ≤30 days of delivery, and in 67 (24%) cases mothers screened positive >30 days before delivery but were untreated. These 2008 data were similar to those reported for 2003 and 2005.

In 2008, 25 (6%) infants with CS were stillborn, and three (1%) died ≤30 days of delivery, for a case fatality ratio of 6.5%. In 2003, 29 (7%) infants with CS were stillborn, and four (1%) died ≤30 days of delivery, for a case fatality ratio of 7.6%.

Reported by

JR Su, MD, SM Berman, MD, D Davis, HS Weinstock, MD, Div of STD Prevention, National Center for HIV, Hepatitis, STD, and TB Prevention; RD Kirkcaldy, MD, EIS Officer, CDC.

Editorial Note

The increase in the CS incidence rate from 2005 to 2008 reflects an increase in the P&S syphilis rate among women in the United States. After declining from 17.3 cases per 100,000 in 1990 to 0.8 in 2004, the P&S syphilis rate among females increased, particularly in the South (1). In the South, CS rates increased among infants born to black mothers, reflecting the increase in P&S syphilis rates among black women. Recent increases in P&S syphilis among black women in the South have been linked to crack cocaine use and commercial sex work (2). Prevention of CS must rely on prevention of P&S syphilis among women.

In 2008, only 64% of mothers of infants with CS received prenatal care, a percentage virtually unchanged from 2003 and 2005. In contrast, 84% of all live births in the United States in 2005 were to mothers who received early (first trimester) prenatal care (6). Early prenatal care is an essential component of CS prevention because it facilitates early detection and treatment of maternal syphilis. CDC recommends serologic syphilis testing for all pregnant women at the first prenatal visit (7). As of 2003, syphilis screening of pregnant women during the first trimester or at the first prenatal care visit was required by law in 43 states and DC (8). In communities and populations in which the risk for congenital syphilis is high, serologic testing and a sexual history also should be obtained at 28 weeks' gestation and at delivery (7). Any woman who delivers a stillborn infant should be tested for syphilis.

Pregnant women with untreated or inadequately treated syphilis should receive a penicillin regimen appropriate for the stage of syphilis and should be monitored for serologic response to treatment (7). Many pregnant women will deliver before their serologic response to treatment can be assessed definitively. In partnership with prenatal care providers, health departments should explore strategies to coordinate and monitor syphilis care for pregnant women.

The findings in this report are subject to at least two limitations. First, infants who are not infected with syphilis might be included among those with probable CS because a case can be defined solely based on the mother's history of diagnosis, treatment, and follow-up. Second, incomplete reporting or inconsistent application of the case definition might have occurred in some localities or states (e.g., because all mothers of stillborn infants might not have been tested for syphilis, reporting of stillborn CS cases likely is incomplete). A recent report demonstrated that innovative surveillance strategies, such as cross-matching syphilis laboratory reports with live birth and fetal death registries, can enhance CS case detection and increase the number of cases reported (9).

The increase in the P&S syphilis rate from 1.1 per 100,000 females in 2007 to 1.5 in 2008 (1) might portend a larger increase in the CS rate in 2009 and future years. The increase in the CS rate, the substantial burden of P&S syphilis among black women in the South, and the high case-fatality ratio associated with CS require that CS prevention be given high priority in areas with high syphilis morbidity and evidence of heterosexual syphilis transmission.

References

1. CDC. Sexually transmitted disease surveillance, 2008. Atlanta, GA: US Department of Health and Human Services, CDC; 2009. Available at http://www.cdc.gov/std/stats08/main.htm. Accessed April 9, 2010.
2. CDC. Primary and secondary syphilis---Jefferson County, Alabama, 2002--2007. MMWR 2009;58:463--7.
3. United States Preventive Services Task Force. Screening for chlamydial infection: recommendation statement. Available at http://www.guideline.gov/summary/summary.aspx?ss=15&doc_id=10408&nbr=5454&string=. Accessed April 9, 2010.
4. Chou R, Smits AK, Huffman LH, Fu R, Korthuis PT. Prenatal screening for HIV: a review of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med 2005;143:38--54.
5. United States Preventive Services Task Force. Counseling to prevent tobacco use and tobacco-caused disease. Available at http://www.ahrq.gov/clinic/uspstf/uspstbac.htm. Accessed April 9, 2010.
6. National Center for Health Statistics. Health, United States, 2008 with chartbook. Hyattsville, MD: US Department of Health and Human Services, CDC, National Center for Health Statistics; 2009.
7. CDC. Sexually transmitted diseases treatment guidelines, 2006. MMWR 2006;55(No. RR-11).
8. Hollier LM, Hill J, Sheffield JS, Wendel GD Jr. State laws regarding prenatal syphilis screening in the United States. Am J Obstet Gynecol 2003;198:1178--83.
9. Winscott M, Taylor MM, Kenney K. Identifying unreported and undiagnosed cases of congenital syphilis in Arizona using live birth and fetal death registries. Sex Transm Dis 2009. Epub ahead of print.