Are There Increases in Syphilis Among Heterosexual Men in Florida?

Background: Florida classifies syphilis cases as men who have sex with other men (MSM) and men with no evidence of sex with other men (non-MSM) Reported syphilis among non-MSM increased 33% from 2012 (N=955) to 2014 (N=1,272).  We investigated cases to see if this was an increase in heterosexual men or an artifact of surveillance.

Methods: We examined male syphilis cases reported from 2012 through 2014 to Florida’s sexually transmitted disease (STD) surveillance system.  Cases were examined to determine if they were reported as MSM, heterosexual men, or had missing information. Bivariate analyses were performed to make comparisons between the study groups. 

Results: From 2012 through 2014, there were 12,757 men with infectious and latent syphilis including 9,484 (74%) MSM and 3,273 (26%) Non-MSM. The proportion of Non-MSM with an unknown MSM status increased from 20% (N=187) to 31% (N=396) over time.  After excluding cases with unknown responses to MSM status, the actual number of heterosexual  male cases still increased by 14% from 2012 (N=768) to 2014 (N=876).  42% of the increase in Non-MSM was due to increases in heterosexual men and 58% explained by an increase in missing data.  There was a 23% increase among women during this same time frame 2012 (N=1,083) to 2014 (N=1,317). 

Conclusions: There was a real increase (14%) in syphilis among heterosexual men from 2012 to 2014, though some misclassification of MSM status likely remains.  STD programs need to account for missing MSM status when examining syphilis trends.