Developing a Topology of Syphilis in the United States.

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.