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Surveillance for Geographic and Secular Trends in Congenital Syphilis -- United States, 1983-1991

MMWR 42(SS-6);59-71

Publication date: 12/17/1993


Table of Contents

Article

References

POINT OF CONTACT FOR THIS DOCUMENT:

Tables
Incidence of congenital syphilis, by region & by cities & states
Expected & observed cases of congenital syphilis during 2-year...

Figures
Rates of CD and P&S among women -- United States, 1983-1991
Rates of congenital syphilis, by region -- United States, 1983-91
Comparison of the rates of congenital syphilis reported the BDMP


Article

Ruth Ann Dunn, M.D.
Linda A. Webster, Ph.D.
Allyn K. Nakashima, M.D.
Division of Sexually Transmitted Diseases/HIV Prevention National Center for Prevention Services Gregg C. Sylvester, M.D., M.P.H.
Division of Birth Defects and Developmental Disabilities National Center for Environmental Health

Abstract

Problem/Condition: CDC monitors trends in the occurrence of congenital syphilis (CS) in the United States by using surveillance data sent from state and local health departments. Comparisons of data from this surveillance system with data from the Division of Sexually Transmitted Diseases/HIV Prevention and the Birth Defects Monitoring Program (BDMP) can be used to assess the potential effects of changes in case finding and reporting practices on these trends.

Reporting Period Covered: This report covers CS surveillance in the United States for the years 1983-1991.

Description of System: Cases of CS among infants less than 1 year of age and primary and secondary (P&S) syphilis among women are reported quarterly to CDC. The BDMP is a CDC national surveillance system that samples hospital discharge data on U.S. births.

Results: During the period 1983-1991, 12,151 CS cases were reported. Before 1988, regional CS incidence increased 35%-131% annually. Larger increases occurred in the Northeast (578%) in 1989 and in the South (178%), Midwest (244%), and West (777%) in 1990. Within regions, these larger increases were temporally related to increases in P&S syphilis in women and changes to a more sensitive CS case definition.

Interpretation: CS incidence has increased since 1983 in all regions of the United States. Increases since 1988 reflect both changes in surveillance reporting practices--the surveillance case definition for CS was changed in 1988 and further revised in 1989--and a true increase in incidence.

Actions Taken: These data indicate where CS prevention efforts need to be targeted. To facilitate reporting of CS cases, CDC has developed a) a shorter form for reporting cases of CS after 1991 and b) a software package for use by state and local health departments to enter and analyze CS data.

INTRODUCTION

In 1992, more than 40 years since the introduction of penicillin, congenital syphilis (CS) should have been a disease of the past. The infection is largely preventable if pregnant women are tested for syphilis and, if found to be infected, treated with penicillin early in pregnancy (1,2). Failure to prevent transmission of syphilis to the fetus often has devastating consequences: an estimated 40% of pregnancies among women who have untreated early syphilis will result in perinatal death (3). Despite the widespread availability of penicillin and serologic tests for syphilis, CS continues to be a public health problem. In 1991, more cases of CS among infants less than 1 year of age were reported than at any time since surveillance of CS in this age group began in 1951 (4).

The increase in the number of CS cases among infants less than 1 year of age probably represents a true increase in the incidence of CS in the United States. Primary and secondary (P&S) syphilis increased markedly after 1985; this increase was greater for women than men (5). Access to and use of prenatal care by women at high risk for syphilis may have decreased during the 1980s, thus reducing their chances of receiving adequate treatment during pregnancy (6). However, some of the increase in the number of CS cases since 1988 may be explained by changes in CS reporting practices: a more sensitive surveillance case definition for CS was developed in 1988 and further revised in 1989 (7,8). This new definition increased the number of cases considered reportable to CDC. In addition, several areas with high P&S syphilis rates initiated more active surveillance for CS in conjunction with or after the introduction of the surveillance case definition. This change also resulted in an increased number of cases identified and reported to CDC (CDC, unpublished data). Because these changes in CS case-finding and reporting practices did not occur uniformly in all reporting areas, trends in CS incidence can be difficult to interpret.

To examine trends in CS incidence and to assess the potential effects of the changes in CS case finding and reporting practices on these trends, we analyzed data for the number of CS cases reported to CDC from 1983 through 1991.

METHODS

Congenital Syphilis Case Definition

From 1983 through 1987, the Kaufman criteria served as the case definition for reporting CS to CDC. The Kaufman criteria are a combination of clinical and serologic findings that define and classify a case of CS on the basis of the likelihood of infection (9). These complex diagnostic criteria reflect the difficulty of clinical diagnosis and the inadequacy of currently available tests. Most infected infants do not manifest clinical signs at birth, and serologic tests for syphilis (STS) do not reliably indicate infection because of passive transfer of maternal antibody to the fetus.

The Kaufman criteria had limitations as a surveillance and reporting definition for public health use. They required laboratory tests that were not always performed at birth and follow-up STS that were difficult to obtain from infants whose mothers did not use health-care services (10). The sensitivity of the criteria was further diminished because stillbirths due to syphilis were not specifically mentioned in the criteria. Health departments differed in their interpretation of the criteria when they reported cases of CS, especially on the inclusion of infants who were stillborn or who had no signs of CS. For these reasons, the number of reported cases underrepresented the true burden of disease. Recognizing these problems, CDC developed a surveillance case definition for CS in 1988, which was revised in 1989 (7,8). This case definition classifies as "presumptive" the infection of an infant whose mother had untreated or inadequately treated syphilis at delivery, regardless of signs in the infant; or the infection of an infant or child who has a reactive treponemal test for syphilis and any one of the following:

Cases are classified as "confirmed" (among infants) if they are laboratory confirmed. A syphilitic stillbirth is defined as a fetal death in which the mother had untreated or inadequately treated syphilis at delivery of a fetus of greater than or equal to 20 weeks' gestation or of greater than 500 grams birth weight.

The relative simplicity and heightened sensitivity of this case definition (e.g., infants who were stillborn or who had no clinical signs are included) should allow more complete description of the burden of disease in the population.

From 1988 through 1991, health departments used either the Kaufman criteria or the CDC surveillance case definition. Surveys of health departments indicated that the surveillance case definition was not yet widely or uniformly adopted across the United States through 1990 (CDC, unpublished data). By the end of 1991, most but not all areas had adopted the surveillance case definition.

CDC Sexually Transmitted Disease (STD) Surveillance Data: Summary Reports of CS and P&S Syphilis Among Women

Reports of cases of CS and P&S syphilis were received by local and state health departments. For the period 1983-1991, summary data of cases of CS among infants less than 1 year of age and cases of P&S syphilis among women were sent quarterly from state health departments to CDC. Data were available for 50 states and 63 large cities (most of which had populations greater than 200,000).

Denominator Data

Natality data from CDC's National Center for Health Statistics (NCHS) provided numbers of live births for the period 1983-1989; these data were used to compute national incidence (11,12). The incidence of CS among infants less than 1 year of age was calculated as cases per 100,000 live births. The 1990 and 1991 provisional estimates for U.S. live births were used to calculate national CS incidence for those years (13). For the incidence of CS in regions, states, and large cities, we used natality data for the period 1983-1989; 1989 was used as an estimate for 1990 and 1991 births (12). The four geographic regions used in this report (Northeast, Midwest, South, and West) were defined by the U.S. Department of Commerce, Bureau of the Census (14).

Stillbirths were included in the numerator for incidence calculations for two reasons. First, because vital status was not collected in this data base, it was not possible to determine which cases occurred among stillborn infants. Second, on the basis of information from another data base of individual CS case reports, the number of stillbirths was small and unlikely to change incidence substantially. (Cases could not be linked between the two data bases because of incomplete reporting.)

Birth Defects Monitoring Program Data

The Birth Defects Monitoring Program (BDMP) is a CDC national surveillance system that samples hospital discharge data on U.S. births (15). In 1983, the BDMP sampled approximately 800,000 births; more recently, 400,000-500,000 births have been sampled per year. Because hospitals participate in the BDMP voluntarily, the sample is neither random nor completely geographically representative. The percentages of live births sampled in each region are approximately 13% in the Northeast, 22% in the Midwest, 8% in the South, and 19% in the West.

We examined CS data from the BDMP for the period 1983-1991 as an independent measure of CS incidence for the United States. A case of CS was defined as occurring in an infant who received an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnostic code in the range 090.0-090.9.

Other Data Sources

Data for surveillance practices and the case definition in use for the period 1983-1991 were ascertained directly from results of a telephone survey conducted by CDC in 1991 of state and local health department personnel. Passive surveillance was defined as identification of cases through reports of reactive STS in pregnant women or their infants to the health department from hospitals, laboratories, or health-care workers. Active surveillance was defined as identification of cases through regular reviews of hospital or laboratory records for reactive STS in pregnant women or their infants by health department personnel.

Calculating the CS-to-P&S Ratio

We calculated the ratio of CS cases to cases of P&S syphilis among women (the CS-to-P&S ratio) to estimate the number of CS cases per 100 women with P&S syphilis. Cases of P&S syphilis in women in the year preceding CS cases were used to calculate the ratio because the changes in CS incidence lag behind P&S incidence by approximately 1 year (16). This ratio was calculated by assuming that the number of women reported with P&S syphilis was proportional to the size of the pregnant population with infectious syphilis during a given year. For this assumption to be valid, changes in the age and racial/ethnic distribution of women with P&S syphilis were assumed not to substantially alter the fertility rate of this population over the study period. Because no data exist on fertility rates of women with syphilis, these assumptions were tested by applying age- and racial/ethnic-specific fertility rates of U.S. women to the population of women with P&S syphilis. The estimated proportion of women with P&S syphilis who became pregnant was not found to change over time (CDC, unpublished data).

The CS-to-P&S ratio was used to compute the expected number of CS cases in the 2-year period during the implementation of the surveillance definition for different areas. A 2-year period was chosen because the implementation of the surveillance definition usually occurred in stages and affected greater than 1 calendar year. For each area, the expected number of cases was calculated by multiplying the average CS-to-P&S ratio for the 5-year period before the change in case definition by the 2-year total of P&S syphilis cases in women. Cases of P&S syphilis in women were defined as including both the year before and the first year of implementation of the surveillance definition to allow for a year's delay between CS and P&S incidence. For example, the average CS-to-P&S ratio for the 5-year period before the change in case definition in New York City was 10.8 cases per 100 women with P&S syphilis. Therefore, the expected number of CS cases during the 2-year implementation period (1988-1989) was 377 (10.8 multiplied by 3,488 {the number of women with P&S syphilis cases during 1987-1988} divided by 100).

The difference between the observed (reported) CS cases and the expected CS cases, expressed as a percentage of the observed cases, was a crude estimate of the effect of factors other than P&S syphilis among women on reported CS incidence for those years. This difference, when expressed as a percentage of the expected cases, showed how much observed cases exceeded the expected numbers.

RESULTS

Summary CS Data

From 1983 through 1991, 12,151 CS cases in infants less than 1 year of age were reported in the United States. CS incidence increased from 4.3 cases per 100,000 live births (158 cases) in 1983 to 107.0 cases per 100,000 live births (4,398 cases) in 1991; the largest increase in cases occurred after 1988 (Figure 1).

From 1983 through 1988, before the introduction of the surveillance case definition, CS incidence in each region increased at an average annual rate ranging from 35% (Midwest) to 131% (Northeast) (Figure 2). From 1988 through 1989, CS incidence in the Northeast increased 578% (from 21.9 to 148.5 cases per 100,000 live births); the incidence in the West declined slightly (from 14.5 to 9.8 cases per 100,000 live births) (Table 1). From 1989 through 1990, CS incidence increased 178% in the South (from 33.8 to 93.9 cases per 100,000 live births), 777% in the West (from 9.8 to 86.0 cases per 100,000 live births), and 244% in the Midwest (from 9.3 to 32 cases per 100,000 live births). In 1991, the Northeast had the highest rate of CS (186.2 cases per 100,000 live births), followed by the South (120.9 cases per 100,000 live births), the West (80.6 cases per 100,000 live births), and the Midwest (54.8 cases per 100,000 live births) (Table 1).

CS incidence in the Northeast was primarily affected by two cities -- New York City and Philadelphia. From 1988 through 1991, CS cases in New York City and Philadelphia accounted for 87% of cases in the Northeast and for 92% and 95% of cases in New York and Pennsylvania, respectively. During the same period, 87% of the increase in CS cases in the Northeast was attributable to increases in these two cities.

In contrast, a number of states and large cities contributed to CS incidence in the South. From 1989 through 1991, CS cases from some of the largest Southern cities (Miami, St. Petersburg, and Tampa, Florida; Atlanta, Georgia; New Orleans, Louisiana; Baltimore, Maryland; Dallas and Houston, Texas) contributed only 33% of cases in the South, which suggests that CS occurrence was also substantial in less highly urbanized areas. From 1989 through 1990, 81% of the increase in CS cases in the South was attributable to five states -- Florida, Georgia, Louisiana, Maryland, and Texas. The increase in 1991 was attributed primarily to increases in two large urban areas (Washington, DC, and Miami, Florida) where large increases offset decreases in several other cities and states. In 1991, the incidence in Washington, DC, and Miami exceeded that in New York City and Philadelphia.

Cases of CS in California were the source of most of the increase in the West after 1989. In 1990, 65% of the increase in incidence was attributable to the increase in Los Angeles, where the incidence increased 1,155% (from 49.3 to 618.5 cases per 100,000 live births). In 1991, the incidence in the West decreased as a result of decreases in Los Angeles and the rest of California.

CS incidence in the Midwest, as in the Northeast, occurred primarily in two large urban areas -- Chicago and Detroit. These two cities contributed 69% of cases in the Midwest from 1989 through 1991. In addition, they accounted for 71% of the increase in CS in 1990 and 43% of the increase in 1991. An additional 29% of the increase in 1991 was attributable to cases reported from Illinois and Michigan, excluding Chicago and Detroit.

Surveillance Practices

From 1983 through 1991, most areas used passive surveillance to find CS cases. Some areas (i.e., Dallas, Houston, and Los Angeles) had established active surveillance practices before 1983 that did not change through 1991. Some areas initiated active surveillance during the period 1983-1991. These areas included Chicago in 1990; Detroit in 1991; Louisiana in 1989; Maryland, excluding Baltimore, in 1989; and New York City in 1988.

Comparison of Expected and Observed CS Cases

For selected areas with high incidence, observed (reported) cases during the 2-year implementation period were higher than expected (mean percentage increase: 528%; range: 134%-1,300%) based on the CS-to-P&S ratio (Table 2). The mean percentage increase was greater among areas that adopted active surveillance during the implementation of the surveillance definition than among areas that continued passive surveillance (576% vs. 462%).

Overall, the average percentage difference between observed and expected cases was 77% (range: 57%-93%) (i.e., an average 77% of observed CS cases could not be explained by trends in P&S syphilis cases among women).

Before the change in case definition, the CS-to-P&S ratio differed widely among areas (range: 0.9-15.3). During the implementation of the surveillance definition, the CS-to-P&S ratio increased in all areas; however, the increase was uneven (range: 134%-1,170%) and differences among areas persisted. Three of five areas that adopted active surveillance during the implementation of the surveillance definition (Chicago, Detroit, and New York City) had smaller changes in the CS-to-P&S ratio than did areas that maintained passive surveillance practices.

BDMP Data

From 1983 through 1991, the BDMP detected a trend in CS similar to the trend seen in the STD surveillance system for CS (Figure 3). However, the CS incidence in the BDMP was consistently higher than its incidence in the STD surveillance system. Before 1989, the incidence in the BDMP was 100% to 300% higher than in the STD surveillance system. From 1989 through 1991, the incidence in the BDMP was only 2% to 34% higher. The BDMP surveillance system detected the first substantial increase (50%) in CS incidence 1 year before the STD surveillance system (1987 vs. 1988).

DISCUSSION

The incidence of CS increased throughout the United States during the period 1983 through 1991, and the largest increases occurred after 1988. This trend was seen in each region, although the increases after 1988 differed in magnitude. The most dramatic increases in a single year occurred in the Northeast and the West, reflecting increases in cases reported from New York City and Los Angeles. Similarly, cases reported from major urban areas in the Midwest (Chicago and Detroit) and the South (Washington, DC, and Miami) contributed to large increases in those regions.

The beginning of the increase in CS in each region was closely related to increases in P&S syphilis among women (17). Except in the Midwest, the increase in CS in each region was proportionately larger than the increases in P&S syphilis among women. The increases in CS continued after the incidence of P&S syphilis among women had reached a plateau or declined by 1991. In the Midwest, the CS and P&S syphilis trends were similar and still increasing through 1991.

The timing of the large increases in CS in different areas often coincided with the adoption of the more sensitive CS surveillance case definition. After the surveillance definition was introduced, the proportion of observed cases in excess of those expected (percentage difference) ranged from 60% to 80% for most areas with high incidence. The weighted average of the percentage difference for these areas (75%) could be considered an estimate of the proportion of cases in the United States from 1989 through 1991 that were attributable to the changes in the CS case definition. This estimate should be interpreted only to represent the maximum potential effect of the change in case definition, because other changes in surveillance and reporting during this period could also have contributed to the additional cases observed.

The lack of sensitivity of the Kaufman criteria was an important factor in the magnitude of the increase in CS cases after the surveillance case definition was implemented. The experiences in Florida and Chicago were probably typical of the areas that already included infants without signs of CS and stillbirths in their case definition. Other areas, such as Los Angeles County, which previously included only infants with clinically apparent CS, were likely to report greater increases under the surveillance case definition. These three areas had also estimated the increase in cases by examining their records to determine how many infants would have been reported as having CS cases under the surveillance definition before it was implemented. In Florida, 25% more cases would have been reported (R.S. Hopkins, personal communication); in Chicago, 50% more cases would have been reported (L. Galaska, personal communication). In Los Angeles County, 295% more cases would have been reported if only the infants already known to the health department were included in the analysis (18). Similar to our findings, the estimated increases were lower for Florida and Chicago than for Los Angeles.

The difference between our estimates of the increase in cases following implementation of the surveillance definition and the estimates of local and state health departments may be explained by several factors. The evaluations done by the health departments compared cases for a single year and were not affected by other surveillance and reporting changes. In our analysis, two periods of time were compared. Between the comparison periods, surveillance and reporting may have improved or the risk of having an infant with CS among women with syphilis may have increased. Other important surveillance factors that could have influenced the changes in CS incidence include syphilis screening policies in states and municipalities, testing policies in hospitals, reporting practices in hospitals, and the number of health-department personnel available to monitor reporting practices and investigate possible CS cases.

In addition, the change from passive to active surveillance could have contributed substantially to the reported increases in the number of cases. In areas where syphilis testing was mandatory at delivery and where health departments conducted active surveillance of laboratory and hospital records, a higher proportion of infants infected with CS would have been identified than in areas where these practices were not in place. After areas were stratified by the surveillance method used during the implementation period, the average percentage increase was greater for areas that changed to active surveillance; this finding indicates that changing to active surveillance increased the number of reported cases in addition to the change in the case definition. Because these changes occurred simultaneously, the proportion of the increase contributed by each of these changes is difficult to measure.

Although changes in surveillance and reporting practices affected CS trends, several factors suggest a true increase in CS incidence has occurred. First, increases were occurring in most areas before the surveillance case definition was implemented. Second, the number of cases during the implementation of the surveillance definition was also predicted to be higher on the basis of increases in the number of cases of P&S syphilis among women. Third, in large cities that had not changed case definition or surveillance practices through 1991 (e.g., Baltimore and Dallas), increases in CS incidence were still noted. Finally, an increase in CS after 1986 was also demonstrated by an independent surveillance system, the BDMP. The higher CS incidence in the BDMP data indicates that, before 1989, the CS surveillance system may not have been adequately describing the burden of disease. After 1988, the decrease in the difference in incidence reported by the two systems (2% vs. 34%) indicates that the sensitivity of the CS surveillance system had improved.

Alternatively, selection and reporting biases in the BDMP may account for the higher incidence observed by use of this surveillance system. First, the BDMP may have oversampled hospitals in areas with high syphilis morbidity, mandatory syphilis testing practices, or better detection methods for CS. To determine if CS cases from cities with high syphilis morbidity contributed more to incidence in the BDMP system compared with the STD system, BDMP and STD data were reanalyzed after data were excluded for cases from six large cities (Chicago, Detroit, Los Angeles, Miami, New York City, and Philadelphia). We found that CS incidence in both systems decreased; however, incidence in the BDMP system remained higher than in the STD system for all years except 1990 and 1991. After 1987, these six large cities accounted for 52% of the CS incidence each year in both the STD and BDMP surveillance systems. These findings indicate that the selection of hospitals in six cities with high syphilis morbidity did not account for the difference between the two systems.

An important reporting bias in the BDMP was the lack of a case definition for CS. The BDMP system used ICD-9-CM diagnostic codes, which did not specify the criteria for the diagnosis of CS. Thus, infants may have been included who would not have met the CDC criteria for CS. For example, in some hospitals, all infants who had reactive STS at birth may have been diagnosed and treated as having CS, regardless of maternal history. Similarly, changes to more sensitive detection methods among selected hospitals could have caused some of the increase in incidence in the BDMP system after 1986.

RECOMMENDATIONS

To improve the detection and reporting of CS, health departments should a) ensure that all personnel responsible for CS case investigation and reporting understand and consistently use the surveillance case definition; b) ensure that hospitals with obstetrical services in areas with high syphilis incidence test all women for syphilis at the time of delivery and that test results be available before the mother and infant are discharged from the hospital; and c) teach the medical community how to evaluate and treat infants suspected of having CS and how to report these cases to the health department.

Health departments also should regularly evaluate surveillance data to ensure that all cases of CS are being identified. The CS-to-P&S ratio may be useful as a measure of effective case finding. Although no single ratio should be attained by all areas, areas with high syphilis morbidity that identify substantially fewer CS cases per 100 women with P&S syphilis than do other high morbidity areas should evaluate the effectiveness of their case finding. This evaluation should include a review of hospital or laboratory records for additional cases of CS and a review of the adequacy of current syphilis testing policies for pregnant women. A low CS-to-P&S ratio should not be assumed to demonstrate successful prevention of CS. Prevention effectiveness can be evaluated only after CS case-finding activities appropriate to the level of syphilis morbidity in the area have been well established. A high ratio should prompt a reevaluation of prevention efforts.


References

References

  1. Ingraham NR, Beerman H. The present status of penicillin in the treatment of syphilis in pregnancy and infantile congenital syphilis. Am J Med Sci 1950;219:433-42.
  2. Platou RV. Treatment of congenital syphilis with penicillin. Adv Pediatr 1949;4:39-86.
  3. Ingraham NR. The value of penicillin alone in the prevention and treatment of congenital syphilis. Acta Derm Venereol 1951;31(suppl 24):60-88.
  4. Venereal Disease Program, Public Health Service. VD fact sheet. Washington, DC: US Department of Health, Education, and Welfare, Public Health Service, December 1954:16; PHS publication no. 341.
  5. Rolfs RT, Nakashima AK. Epidemiology of primary and secondary syphilis in the United States, 1981 through 1989. JAMA 1990;264:1432-7.
  6. Brown SS, ed. Prenatal care: reaching mothers, reaching infants. Washington, DC: National Academy Press;1988:45-51.
  7. CDC. Guidelines for the prevention and control of congenital syphilis. MMWR 1988;37 (suppl 1):1-13.
  8. CDC. Congenital syphilis -- New York City, 1986-1988. MMWR 1989;38:825- 9.
  9. Kaufman RE, Jones OG, Blount JH, Wiesner PJ. Questionnaire survey of reported early congenital syphilis: problems in diagnosis, prevention, and treatment. Sex Transm Dis 1977;4:135-9.
  10. Zenker PN, Berman SM. Congenital syphilis: reporting and reality. Am J Public Health 1990;80:271-2.
  11. National Center for Health Statistics. 1983 to 1988 Natality detail {Public use data tape documentation}. Hyattsville, MD: US Department of Health and Human Services, Public Health Service, CDC, 1983-1988.
  12. National Center for Health Statistics. Advance report of final natality statistics, 1989. Hyattsville, MD: US Department of Health and Human Services, Public Health Service, CDC, 1991;40:38-40. (Monthly vital statistics report).
  13. National Center for Health Statistics. Births, marriages, divorces, and deaths for 1991. Hyattsville, MD: US Department of Health and Human Services, Public Health Service, CDC, 1992;40:1. (Monthly vital statistics report).
  14. Bureau of the Census. Geographic identification code scheme; 1980 Census of Population and Housing: 3,10; PHC80-R5. Washington, DC: US Department of Commerce, Bureau of the Census, April 1983.
  15. Edmonds LD, Layde PM, James LM, Flynt JW, Erickson JD, Oakley GP. Congenital malformations surveillance: two American systems. Int J Epidemiol 1981;10:247-52.
  16. Schulz KF, Murphy FK, Patamasucon P, Meheus AZ. Congenital syphilis. In: Holmes KK, Mardh PA, Sparling PF, Wiesner PJ. Sexually transmitted diseases. 2nd ed. New York, NY: McGraw-Hill;1990:822.
  17. Webster LA, Rolfs RT, Nakashima AK, Greenspan JR. Regional and temporal trends in the surveillance of syphilis, United States, 1986-1990. In: CDC surveillance summaries, December 1991. MMWR 1991;40(No. SS-3):29- 33.
  18. Cohen D, Boyd D, Prabhudas I, Mascola L. The effects of case definition, maternal screening, and reporting criteria on rates of congenital syphilis. Am J Public Health 1990;80:316-7.


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Table 1

TABLE 1. Incidence * of congenital syphilis, by region and by cities and states with
highest incidence -- United States, 1987-1991
======================================================================================
                      1987        1988        1989        1990        1991
----------------------------------------------------------------------------
Northeast               20.3        21.9       148.5       179.8       186.2
  New York City         98.5       104.4       765.6       756.6       736.2
  Philadelphia          45.5        62.1        78.5       611.0     1,027.4

Midwest                  1.7         2.7         9.3        32.0        54.8
  Detroit               15.0        25.3        83.2       267.3       306.7
  Chicago               14.5        24.8        94.4       278.0       420.4

South                   15.7        25.1        33.8        93.9       120.9
  Florida +             53.0        85.7        79.1       293.8       203.7
  Georgia                6.8         5.7        12.7        76.2       126.1
  Maryland               2.8         7.9        25.6       104.8        69.0
  Miami                156.2       440.9       533.7       412.9     1,283.9
  New Orleans            0.0         0.0       299.2       993.8       288.5
  Texas                 14.9        13.8        31.2        68.3        84.5
  Washington, DC        19.6        47.4        84.8       246.0     2,086.7

West                     8.6        14.5         9.8        86.0        80.6
  California &           6.5        10.3         9.4        51.6        45.4
  Los Angeles           52.7        96.7        49.3       618.5       599.2
----------------------------------------------------------------------------
* Number of cases per 100,000 live births.
+ Excludes Miami.
& Excludes Los Angeles.
======================================================================================


Table 2

TABLE 2. Expected and observed (reported) cases of congenital syphilis during the 2-year period of implementation of the
surveillance case definition, by method of surveillance -- selected areas with high incidence, United States, 1988-1991
============================================================================================================================================
                                                                    Cases
                           Average
                       CS-to-P&S ratio        2-year                                                                      CS-to-P&S ratio
Surveillance method/        before        implementation     P&S         CS         CS           %             %              during
Area                   implementation *       period       syphilis  expected +  observed    increase &   difference @   implementation **
------------------------------------------------------------------------------------------------------------------------------------------
Passive continuous
  Florida ++                  5.3            1990-91        4,418       234         862         268          72.8             19.5
  Georgia                     0.9            1990-91        3,308        30         223         643          86.5              6.7
  Miami                      12.3            1990-91          840       103         337         227          69.4             40.1
  Philadelphia                6.6            1990-91        1,876       124         480         287          74.2             25.6
  Washington, DC              5.1            1991             483        25         246         884          89.8             50.9

Active continuous
  Los Angeles                 4.4            1990-91        1,809        80       1,012       1,165          92.1             55.9

Passive-active
  Chicago                    15.3            1990-91          922       141         407         189          65.4             44.1
  Detroit                    10.3            1990-91          502        52         131         152          60.3             26.1
  New Orleans                 0.9            1988-89          255         2          28       1,300          92.9             11.0
  Maryland                    1.4            1989-90          662         9         102       1,033          91.2             15.4
  New York City              10.8            1988-89        3,488       377       1,150         205          67.2             33.0

Mixed &&
  California @@               4.9            1990-91        2,017        99         472         377          79.0             23.4
  Texas                       5.0            1990-91        4,014       201         470         134          57.2             11.7
------------------------------------------------------------------------------------------------------------------------------------------
 * The average ratio of CS cases to P&S syphilis cases among women during the 5-year period before the implementation of the
   surveillance case definition.
 + The expected number of CS cases was calculated as {(average CS-to-P&S ratio before implementation) x (number of P&S syphilis
   cases among women reported)}/100.
 & The percentage increase was calculated as {(observed - expected) / expected} x 100. For Washington, DC, this increase was calculated
   by using observed cases for a 1-year period.
 @ The percentage difference was calculated as {(observed - expected) / observed} x 100. For Washington, DC, this difference was
   calculated by using observed cases for a 1-year period.
** The average ratio of CS cases to P&S syphilis cases among women for the 2-year implementation period.
++ Excludes Miami.
&& Surveillance practices differed among cities in both states.
@@ Excludes Los Angeles.

CS=Congenital syphilis.
P&S syphilis=Primary and secondary syphilis.
============================================================================================================================================


Figure 1

Rates of CD and P&S among women -- United States, 1983-1991

Prevention Guidelines Image


Figure 2

Rates of congenital syphilis, by region -- United States, 1983-91

Prevention Guidelines Image


Figure 3

Comparison of the rates of congenital syphilis reported the BDMP

Prevention Guidelines Image




This page last reviewed: Friday, July 25, 2014
This information is provided as technical reference material. Please contact us at cwus@cdc.gov to request a simple text version of this document.
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