Epidemic Early Syphilis -- Montgomery County, Alabama, 1990-1991

In Montgomery County (1990 population: 209,085), Alabama, an epidemic of early syphilis (ES) (i.e., primary, secondary, and early latent) involving 1010 cases occurred from August 1990 through November 1991 (Figure 1). From June 17 through November 7, 1991, the Alabama Department of Public Health (ADPH) and CDC initiated an intervention campaign to reduce the incidence of ES; the intervention increased case-finding primarily through partner notification (PN) and cluster investigations. * This report assesses the intervention campaign by describing 1) the results of PN/cluster investigation interviews during the intervention, 2) the relation between reported crack cocaine use and PN/cluster investigation results, 3) a comparison of interview results for the first 6 weeks of the campaign (i.e., early campaign period) with the 6-week period immediately before the campaign (i.e., precampaign period), and 4) the syphilis morbidity trends for 1990 and 1991.

To conduct this campaign, the ADPH increased from 45 to 71 the weekly number of hours the county sexually transmitted disease (STD) clinic was open, increased from eight to 22 the number of public health workers assigned to syphilis intervention, provided supplemental training in PN/cluster investigation techniques, and intensified supervision throughout the intervention period. To enhance analysis of trends in syphilis incidence, trends for only those case-patients who self-referred with primary and secondary syphilis were analyzed. PN/Cluster Investigation Interview Results

During the intervention campaign, 373 case-patients were interviewed and provided sufficient information to initiate efforts to locate 984 sex partners. ** Of these, 696 (71%) were examined: 113 (11%) had syphilis and were treated, and 547 (56%) were given prophylactic antibiotic treatment. In addition, case-patients provided information to initiate efforts to locate 1446 high-risk associates. *** Of these, 1153 (80%) were examined: 41 (3%) had syphilis and were treated, and 836 (58%) were treated prophylactically.

The 116 (31%) case-patients who identified at least one infected sex partner or high-risk associate could not be distinguished from the remaining case-patients by demographics, disease stage, or manner in which the case-patients were detected. Relation Between Crack Cocaine Use and PN/Cluster Investigation Results

Information about risk behaviors was provided by 352 (94%) of the 373 case-patients. Of the 198 males, 40 (20%) reported crack cocaine use. Exchanging sex for drugs was more likely to be reported by those who reported crack cocaine use (seven {18%} of 40) than by those who did not (nine {6%} of 158) (prevalence ratio {PR}=3.1; 95% confidence interval {CI}=1.2-7.8). Of the 154 females, 32 (21%) reported crack cocaine use. Exchanging sex either for drugs or money was more likely to be reported by those who reported crack cocaine use (24 {75%} of 32) than by those who did not (six {5%} of 122) (PR=15.3; 95% CI=6.8-34.1).

Compared with nonusers, crack cocaine users reported, on average, nearly twice as many sex partners per case (8.4 versus 4.7 {p less than 0.01}) during the interview period **** but more than three times as many sex partners per case for whom interviews yielded insufficient information to initiate PN/cluster investigations (4.8 versus 1.5 {p less than 0.01}). Although more PN/cluster investigations were initiated for crack cocaine users than for nonusers per case (6.5 versus 6.0), these investigations found 28% fewer infected persons (0.31 versus 0.43 per case), and 14% fewer persons (3.2 versus 3.7) who received prophylactic antibiotic treatment. Comparison of Early Campaign Period with Precampaign Period Interview Results

Compared with the precampaign period, the number of new ES cases identified through PN/cluster investigations increased during the early campaign period by 165% (from 23 to 61); the number identified through screening, 79% (from 24 to 43); and the number identified through self-referral, 52% (from 31 to 47). Overall, the number of new case-patients interviewed increased 94% (from 78 to 151). These 151 early campaign period case-patients provided sufficient information to initiate efforts to locate on average 6.8 previously unevaluated sex partners and high-risk associates per case-patient; while the 78 precampaign case-patients provided sufficient information to initiate efforts to locate on average 4.6 previously unevaluated sex partners and high-risk associates per case-patient.

Comparing the early campaign with the precampaign period, the average number of infected persons per case was similar (0.48 versus 0.37 {p=0.66}); however, the average number of persons prophylactically treated per case was greater (3.9 versus 2.5 {p less than 0.01}). Most of the differences in PN/cluster investigation productivity between the early campaign and precampaign periods reflected the substantial increase in the number of high-risk associates identified during the early campaign period. Syphilis Morbidity Trends for 1990-1991

During 1990, the number of ES cases ranged from 20 to 56 cases per month (Figure 1). In comparison, during February-March 1991, cases increased from 27 to 132 per month before declining during October-December. By month of treatment (data available for 1991 only), the number of ES cases peaked in July before declining by December. Reported bimonthly, the number of self-referred primary and secondary syphilis case-patients (data available for 1991 only) increased from 38 during January/February to 49 during March/April and gradually declined to 18 during November/December.

Reported by: C Sims, J Hill, M Rizer, MD, T Miller, MD, Montgomery County Health Dept; D Beard, M Kerr, M O'Cain, D Williamson, MD, C Woernle, MD, State Epidemiologist, Alabama Dept of Public Health. Div of Sexually Transmitted Diseases and HIV Prevention, National Center for Prevention Svcs; Div of Field Epidemiology, Epidemiology Program Office, CDC.

Editorial Note

Editorial Note: The goals of syphilis-prevention programs are to interrupt sexual transmission; prevent fetal loss and congenital syphilis (CS) and its complications; and prevent late complications in adults. Early detection, treatment of persons known to be infected, and prophylactic antibiotic treatment of those likely to be infected are methods to interrupt sexual transmission and prevent transmission from mother to unborn child. Case-finding can be enhanced through screening, PN/cluster investigation, or increased self-referrals as a result of education and/or reduced barriers to health care.

Previous reports have suggested that interventions emphasizing PN in cocaine-related STD outbreaks are inadequate because cocaine users do not provide sufficient information to enable public health workers to locate their sex partners (1,2). However, in Montgomery County, public health workers were able to combine PN and cluster investigation techniques to increase identification of infected and potentially infected sex partners and high-risk associates of syphilis case-patients by increasing STD clinic hours and personnel, providing supplemental training, and intensifying supervision.

In particular, use of cluster investigations emphasized identification of high-risk associates (who would have otherwise gone undetected and unexamined) and thereby substantially increased the number of persons who received prophylactic antibiotic treatment. However, the impact of prophylactic treatment in any STD outbreak is difficult to evaluate because the proportion of persons at increased risk (i.e., high-risk associates) that actually have incubating syphilis is not estimable; the impact can be estimated for persons with known exposure to syphilis (i.e., sex partners).

PN/cluster investigation efforts may be more efficient when directed toward groups that yield greater numbers of infected persons; identifying characteristics (e.g., demographics) of these targeted groups is critical. During this outbreak, however, because characteristics of syphilis case-patients who had infected sex partners or high-risk associates were similar to those who did not, no target group was identified.

With this intervention campaign, incidence of syphilis, as measured by self-referred primary and secondary cases, declined 63% (from 49 cases during March/April to 18 cases during November/December), although the decline appears to have begun before the intervention was initiated. Use of both PN and cluster investigations, as well as additional personnel who receive supplemental training in PN/cluster investigation techniques and intensified supervision, should be considered in intervention campaigns for other syphilis outbreaks. Continued evaluation of these methods, including monitoring trends among self-referred primary and secondary case-patients, will be crucial to determine their effectiveness in stemming syphilis outbreaks.

References

1. Andrus JK, Fleming DW, Harger DR, et al. Partner notification: can it control epidemic syphilis? Ann Intern Med 1990;112:539-43.

2. Rolfs RT, Goldberg M, Sharrar RG. Risk factors for syphilis: cocaine use and prostitution. Am J Public Health 1990;80:853-7.

* Cluster investigations are designed to identify persons (other than sex partners) at high risk for syphilis. In this report, persons identified through cluster investigations are referred to as high-risk associates. 

** An additional 240 sex partners were identified who had already been evaluated by the ADPH; no additional efforts were made to locate and evaluate these persons. 

*** An additional 731 high-risk associates were identified who had already been evaluated by the ADPH; no additional efforts were made to locate and evaluate these persons. 

**** Defined as the interval during which sexual contact may have resulted in transmission of syphilis. For primary stage syphilis, the interview period is 3 months plus the duration of disease symptoms; for secondary, 6 months plus duration of disease symptoms; and for early latent, 1 year.

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