Background: This analysis describes co-infection with HIV among individuals with early syphilis, by stage of syphilitic infection, across multiple states of the U.S.
Methods: Case data from areas that reported stage of infection, sex of sex partner, and either HIV-positive or -negative status for ≥70% of cases of primary, secondary, and early latent syphilis reported each year during 2009–2012 were reviewed. Percent co-infected was calculated using individuals with HIV-positive status as the numerator, and individuals with either HIV-positive or HIV-negative status as the denominator.
Results: Data were analyzed from 16 states and Washington DC, comprising 57% of early syphilis morbidity in 2012 (51% of reported HIV morbidity in 2011). Proportions by stage of infection and proportions co-infected varied little during 2009–2012, so 2012 data are presented here. During 2012, 10,657 cases of early syphilis among MSM (15% primary, 39% secondary, 46% early latent (EL)), 2,174 cases among men having sex with women only (MSW) (22% primary, 34% secondary, 44% EL) and 2,098 cases among women (8% primary, 32% secondary, 60% EL) were reported. For primary syphilis, 42% of MSM, 6% of MSW, and 2% of women were co-infected with HIV. For secondary syphilis, 59% of MSM, 17% of MSW, and 6% of women were co-infected. For EL syphilis, 66% of MSM, 12% of MSW, and 4% of women with early latent syphilis were co-infected. Regardless of age group or race/ethnicity, co-infection was lower among individuals with primary syphilis (compared to secondary or EL syphilis).
Conclusions: Co-infection was consistently lower among individuals diagnosed with primary syphilis compared to secondary or EL syphilis. However, MSW were more likely to be diagnosed during primary syphilis, compared to MSM or women. Efforts to reduce transmission of syphilis (and co-infection with HIV) should promote earlier detection.