Gang-Related Outbreak of Penicillinase-Producing Neisseria Gonorrhoeae and Other Sexually Transmitted Diseases -- Colorado Springs, Colorado, 1989-1991

In April 1990, the El Paso County (Colorado) Health Department (EPCHD) recognized an outbreak of penicillinase-producing Neisseria gonorrhoeae (PPNG) and other sexually transmitted diseases (STDs) occurring in Colorado Springs (1990 census population: 397,014), Colorado. An investigation by the EPCHD and the Colorado Department of Health eventually identified 56 cases of PPNG from December 1989 through March 1991 (Figure 1). The outbreak revealed a previously unidentified core group of persons with STDs in Colorado Springs. This report summarizes traditional and innovative measures used to investigate and manage the outbreak, and describes this core group and its role in STD transmission in Colorado Springs.

Disease intervention specialists (DISs) used both traditional (e.g., partner notification and referral) and innovative (e.g., ethnographic methods) approaches to obtain the cooperation of persons with PPNG and other STDs (1) and to help identify other persons who had been sexually exposed. Persons were interviewed in STD clinics, in their homes, and at locations where they congregated (e.g., movie theaters, shopping malls, clubs, and bars). Network analysis (2) was performed on case-finding data to characterize sexual and social connections of those identified.

The network analysis included 578 persons connected through social or sexual associations. A densely connected subset of 410 persons (218 men and 192 women) within this network included adolescents and young adults associated with street gangs. These gangs, which originated in Los Angeles and are associated with the crack cocaine trade in the United States, had not been observed in Colorado Springs before May 1988 (3,4). The men in this subset were young (mean age: 21.5 years) and mostly black (87.2%), and the women were younger (mean age: 19.7 years) and more racially / ethnically diverse. During interviews with DISs, many women reported engaging in multiple risk behaviors associated with transmission of STDs (e.g., engaging in frequent sexual encounters with multiple sex partners, exchanging sex for crack cocaine, and heavily using crack cocaine). In comparison, fewer men reported heavy use of crack cocaine, but many reported having engaged in frequent sexual encounters and having had multiple sex partners.

Of the 410 persons in this subset, 300 received medical examinations at public STD clinics, hospitals, and community health centers (Figure 2); of these 300 persons, 248 (83%) were infected with one or more STDs. A total of 390 laboratory-confirmed sexually transmitted infections, including two early syphilis infections, were diagnosed among these 248 persons. A relatively high proportion of those infected with N. gonorrhoeae were coinfected with Chlamydia trachomatis; 18 (46%) of 39 PPNG episodes and 64 (29%) of 222 nonresistant-gonorrhea episodes involved coinfection with C. trachomatis.

During interviews by DISs, 200 (81%) of the 248 persons with infections named 558 sex partners and 571 others in the sociosexual network (5,6). Through outreach efforts (including partner notification and referral), DISs identified 91 persons that represented 130 (33%) of the 390 sexually transmitted infections diagnosed (12 PPNG infections, 62 gonococcal infections, 55 genital chlamydial infections, and one syphilitic infection) (Figure 2); 21 of these infections were identified in other members in the sociosexual network.

During December 1989 - March 1991, the 39 gang-related PPNG cases accounted for 70% of the total 56 cases reported in Colorado Springs. Persons in this core group and their sex partners accounted for 261 (22%) of 1170 gonorrhea infections, 127 (11%) of 1164 chlamydial infections, and two (11%) of 18 infectious syphilis cases during that period.

Reported by: RP Bethea, SQ Muth, JJ Potterat, DE Woodhouse, JD, JB Muth, MD, El Paso County Dept of Health and Environment, Colorado Springs; NE Spencer, MSPH, RE Hoffman, MD, State Epidemiologist, Colorado Dept of Health. Office of the Director, National Center for Chronic Disease Prevention and Health Promotion; Behavioral and Prevention Research Br, Div of Sexually Transmitted Diseases and HIV Prevention, National Center for Prevention Svcs, CDC.

Editorial Note

Editorial Note: Before this outbreak was detected, PPNG in Colorado Springs had been limited to sporadic cases, primarily among military personnel returning from Southeast Asia. From 1976 through 1989, a total of 105 PPNG cases (0.5% of all gonorrhea cases) were reported in Colorado Springs. The investigation of the occurrence of epidemic PPNG revealed a previously unidentified core group that appeared to play an important role in the incidence of many STDs in Colorado Springs. The 213 persons who had 261 episodes of gonorrhea (both PPNG and non-PPNG) during this outbreak represented only 0.1% of the population aged 18-44 years in Colorado Springs. However, this group accounted for 22% of all (1170) reported cases of gonorrhea during a 16-month period. The observation of at least 390 sexually transmitted infections in a group of 410 people and the high percentages of coinfection with other STDs further support the core-group concept for transmission of STDs.

Network analysis indicated that this group was strongly interconnected and comprised predominantly young men and women with social ties to street gangs. These findings correspond with observations from other cities (7) that gonorrhea incidence is unequally distributed and concentrated within certain core populations, and provide added evidence that such groups, once established, may be responsible for maintaining high levels of transmission of many endemic STDs (8,9). Age, sex, race/ethnicity, socioeconomic status, urban residence, cocaine use, or gang affiliation may serve as useful risk markers (7) for identifying core populations at greatest risk for STDs. Further characterization of such groups at elevated risk is needed. Moreover, STD-prevention strategies responsive to the needs of specific populations (e.g., young urban persons) must be developed.

Rapid intervention using traditional case-finding techniques has been associated with the control of both highly focal and communitywide outbreaks of STDs (10). Management of this outbreak further illustrates how specially trained public health professionals, who combine traditional and innovative disease-control strategies, can work with street gang members and other disenfranchised groups (5).

References

1. Holden C. Street-wise crack research. Science 1989;246:1376-81.

2. Klovdahl AS, Potterat J, Woodhouse D, Muth J, Muth S, Darrow WW. HIV infection in an urban social network: a progress report. Bulletin de Methodologie Sociologique 1992;36:24-33.

3. Rinfret M. Cocaine price, purity, and trafficking trends. In: Schober S, Schade C, eds. The epidemiology of cocaine use and abuse, 1991. Silver Spring, Maryland: US Department of Health and Human Services, Public Health Service, National Institute on Drug Abuse, 1991:296-303.

4. Koester S, Schwartz J. Crack, gangs, sex and powerlessness: a view from Denver. In: National Institute on Drug Abuse, ed. Crack pipe as pimp: an eight-city ethnographic study of the sex-for-crack phenomenon -- final report. Silver Spring, Maryland: US Department of Health and Human Services, Public Health Service, National Institute on Drug Abuse, 1991:II-1-II-14.

5. CDC. Alternative case-finding methods in a crack-related syphilis epidemic -- Philadelphia. MMWR 1991;40:77-80.

6. Gerber AR, King LC, Dunleavy GJ, Novick LF. An outbreak of syphilis on an Indian reservation: descriptive epidemiology and disease control measures. Am J Public Health 1989;79:83-5.

7. Rice RJ, Roberts PL, Handsfield HH, Holmes KK. Sociodemographic distribution of gonorrhea incidence: implications for prevention and behavioral research. Am J Public Health 1991;81:1252-8.

8. Yorke JA, Hethcote HW, Nold A. Dynamics and control of the transmission of gonorrhea. Sex Transm Dis 1979;5:51-6.

9. Rothenberg RB. The geography of gonorrhea -- empirical demonstration of core group transmission. Am J Epidemiol 1983;117:688-94.

10. Potterat JJ, Meheus A, Gallwey J. Partner notification: operational considerations. International Journal of STD/AIDS 1991;2:411-5.

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