A9d Giving STDs to Friends: Using Social Network Methods to Study Syphilis and Gonorrhea in Baltimore

Tuesday, March 9, 2010: 11:00 AM
Grand Ballroom C (M4) (Omni Hotel)
Janet Rosenbaum, PhD, AM, STD Center, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, Jacky Jennings, PhD, MPH, General Pediatrics and Adolescent Medicine, Johns Hopkins School of Medicine, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, Jonathan Ellen, MD, School of Medicine Ped Bay Bayview Pediatric Unit, The Johns Hopkins University, Baltimore, MD, Laurel Borkovic, MSEd, STD Center, Division of Infectious Diseases, Johns Hopkins Bayview Medical Center, Baltimore, MD, Jo-Ann Scott, BA, Johns Hopkins Bayview Medical Center, Johns Hopkins Medical Institutions, Baltimore, MD, Charleen Wylie, BA, Infectious Diseases, Johns Hopkins Bayview Medical Center, Baltimore, MD and Anne Rompalo, MD, ScM, School of Medicine, Division of Infectious Diseases, Johns Hopkins University, Baltimore, MD

Background:   STD control traditionally uses sexual contact tracing, but patients may not name all sexual contacts, leaving likely cases unidentified.

Objectives:   This study screens social contacts in addition to sexual contacts of gonorrhea- and syphilis- infected patients and maps the sex and social networks of individuals with incident syphilis.

Methods:  Data was collected from 528 patients at the two Baltimore STD clinics and the Baltimore City Health Department in 2001--2005, including social and sexual contacts of index patients.   Social network size was 331 non-isolates and sexual-only network size was 140 non-isolates.  Data was analyzed using exponential family random graph analysis in the R statnet package.

Results:   Syphilis is clustered within sexual (odds ratio=2.2, 95% confidence interval (1.36, 3.66)) and social contacts (OR=1.31, 95% CI (1.02, 1.68)).  Gonorrhea is clustered within reported  social (OR=1.56, 95% CI (1.22, 2.00)) but not sexual contacts (OR=0.98, 95% CI (0.62, 1.53)).  The number of social and sexual contacts that attend clinic does not differ by index case gender (Fisher p=0.2), race (p=0.5), or syphilis (p=0.3), gonorrhea (p=0.3), chlamydia (p=0.9), or HIV (p=0.5) status.  

Conclusions:  Social contact tracing can yield diagnosed cases of syphilis and gonorrhea that would not be found with sexual contact tracing alone.  Syphilis is clustered more highly within sexual than social contacts, as expected.  Gonorrhea is clustered within social but not sexual contacts.  Gonorrhea index cases may not have reported all sexual contacts if they had not also been asked for social contacts.  Both sexual and social contacts come to clinic irrespective of index case's disease status.  

Implications for Programs, Policy, and/or Research:  Social contact tracing complements sexual contact tracing to increase numbers of identified syphilis and gonorrhea cases.