WP 84 Repeat Syphilis Infections, 2008-2015, Marion County, Indianapolis, Indiana

Wednesday, September 21, 2016
Galleria Exhibit Hall
Justin Holderman, MPH1, Dawne DiOrio, MPA2 and Janet Arno, MD1, 1Bell Flower Clinic, Marion County Public Health Department, Indianapolis, IN, 2Field Assignee, CDC, NCHHSTP, DSTDP and Indiana State Dept of Health, Indianapolis, IN

Background:  The Indianapolis MSA (District 5) has had a steady rise in syphilis for several years and comprises the largest share of morbidity in the state, reporting 133 P&S cases and 119 early latent cases in 2015. A review of literature yielded minimal publications that assessed syphilis reinfection rates by year of diagnosis.  Studies ranged from a reinfection rate of 5.9% within two years (California 2002-2006) to 20% (Baltimore 2010-2011).  

Methods:  Extraction of reported morbidity for primary, secondary, and early latent syphilis in District 5 from 2008-2015 came from Indiana’s STD reporting database, SWIMSS. Individuals were included in 5-year cohorts from the entrance of the patient into the dataset to allow enough time for reinfection to occur while minimizing bias. SAS analysis, including Chi-squared and logistic regression, was used to examine differences in age, race, sex, orientation, HIV status, and syphilis staging diagnosis. 

Results:  Of the 1,362 reported cases of early syphilis, the overall reinfection rate for 2008-2015 was 15.27%. Reinfection rates have increased over time as 2015 alone had a 31% reinfection rate. Of the 208 total patients with repeat syphilis infections, 78% experienced 2 infections, 1.98% had 3 infections, and 1.40% had ≥ 4 infections. In 2015, significant risks for reinfection included MSM orientation (76.2 vs. 93.7%, p=.0019) and HIV+ status (37.0 vs 79.5%, p<.0001). Logistic regression showed that the risk of reinfection was only significant in the HIV+ patients (OR=5.192 [2.526, 10.671]).

Conclusions:  In our analysis, 15.27% of patients experienced more than one syphilis infection. Those with HIV were more likely to have a repeat infection, and the occurrence of repeat infections seems to be increasing over time. Analysis and prevention of repeat syphilis infections is a challenging but important step for enhanced public health efforts to address the groups at highest risk of reinfection.