Developing a Topology of Syphilis in the United States

Abstract

Background: In the United States, reported rates of syphilis continue to increase. Co-occurring epidemics of syphilis among men who have sex with men (MSM) and heterosexual populations create challenges for the prioritization of resources and the implementation of context-specific interventions.

Methods: State was the unit of analysis and was restricted to the 44 states with the most complete data of sex or sex partners for their reported adult syphilis cases. States were classified as high, medium, or low for reported congenital syphilis (CS) and MSM primary and secondary (P&S) syphilis rates. Average values of a range of ecologic state level variables were examined among the 9 categories created through the cross-tabulation of CS and MSM P&S syphilis rates. Patterns among ecologic factors were assessed across the 9 categories of states' syphilis rates.

Results: Among the 44 states categorized, 4 states had high rates of both CS and MSM P&S syphilis in 2015, whereas 12 states fell into the medium/medium category and 7 into the low category. Six states had high CS and medium MSM syphilis and 4 states had medium CS but high MSM syphilis. Several area-level factors, including violent crime, poverty, insurance status, household structure and income, showed qualitative patterns with higher rates of CS and MSM P&S syphilis. Higher proportions of urban population were found among states with higher CS rates; no trend was seen with respect to urbanity and MSM P&S syphilis.

Conclusions: Several area-level factors were associated with CS and MSM P&S syphilis in similar ways, whereas other ecologic factors functioned differently with respect to the 2 epidemics. Explorations of community and area-level factors may shed light on novel opportunities for population specific prevention of syphilis.

Figure 1.

Reported rates of CS and primary and secondary syphilis among men who have sex with men 44 states, 2015.

Figure 2.

Proportion of the state population residing in an urban county (2015) by state-level categorization of reported CS and MSM P&S Syphilis Rates (2015). *Horizontal line represents mean. Proportion urban—The percentage of the state population that resides in urban counties according to the 5-year summary file data from the American Community Survey (2011–2015) and the 2013 Urban-rural Classification Scheme for Counties from National Center for Health Statistics. CS rates classified as High represent the 10 states with the highest reported CS rate in 2015; Medium, the 19 states with the highest rates of reported CS syphilis in 2015 after the 10 High States; Low, the 15 states with no reported CS in 2015. MSM P&S syphilis rates were classified as High for the 10 states with the highest reported MSM P&S Syphilis Rates in 2015, medium—for the 24 states with the next highest MSM P&S syphilis rates in 2015, and Low for the 10 states with the lowest reported MSM P&S syphilis rates in 2015. AL, Alabama; AK, Alaska; AZ, Arizona; AR, Arkansas; CA, California; CT, Connecticut; CO, Colorado; FL, Florida; HI, Hawaii; ID, Idaho; IA, Iowa; IL, Illinois; IN, Indiana; KS, Kansas; KY, Kentucky; LA, Louisiana; MA, Massachusetts; MD, Maryland; ME, Maine; MI, Michigan; MN, Minnesota; MO, Missouri; MS, Mississippi; MT, Montana; NH, New Hampshire; NJ, New Jersey; ND, North Dakota; NM, New Mexico; NC, North Carolina; NV, Nevada; OK, Oklahoma; OH, Ohio; OR, Oregon; PA, Pennsylvania; RI, Rhode Island; SC, South Carolina; SD, South Dakota; TN, Tennessee; TX, Texas; UT, Utah; VA, Virginia; VT, Vermont; WA, Washington; WV, West Virginia.

Figure 3.

Proportion of the state population living in poverty (2015) by state-level categorization of reported CS and MSM P&S Syphilis Rates (2015). *Horizontal line represents mean. Proportion poverty—the percentage of the population living in households at or below the poverty threshold. CS rates classified as High represent the 10 states with the highest reported CS rate in 2015; medium, the 19 states with the highest rates of reported CS syphilis in 2015 after the 10 High States; Low, the 15 states with no reported CS in 2015. MSM P&S syphilis rates were classified as High for the 10 states with the highest reported MSM P&S Syphilis Rates in 2015, medium—for the 24 states with the next highest MSM P&S syphilis rates in 2015, and Low for the 10 states with the lowest reported MSM P&S syphilis rates in 2015.