OBJECTIVES: Substantial biologic and epidemiologic data indicate the importance of syphilis as a potential cofactor for sexual transmission of HIV infection, but few detailed data exist on the geographic covariation of these two important sexually transmitted infections. DESIGN: HIV prevalence in childbearing women and primary and secondary (P&S) syphilis data from 29 states were examined to explore the importance of the epidemiology of syphilis as a factor in facilitating HIV transmission. METHOD: The spatial relationship between P&S syphilis and HIV infection in the health districts of 29 states was analyzed and adjusted for demographic and socioeconomic factors such as racial composition, income, housing, education levels, and access to medical services using the 1990 US census, and geographic location. RESULTS: In 29 states and the District of Colombia, 448 health districts, representing more than 75% of the US population, reported HIV prevalence rates for mothers' district of residence. The HIV seroprevalence ranged from 0 to 1258/10 000 in these health districts. The incidence of P&S syphilis from 1984-1994 in these districts ranged from 0 to 87/100 000. The P&S syphilis incidence was positively associated with the prevalence of HIV infection among childbearing women (P < 0.0001). CONCLUSIONS: Syphilis that persists in communities in the United States appears to represent a 'sentinel public health event' reflecting risk for sexual HIV transmission. These findings, along with other biologic and epidemiologic information, reinforce the importance of syphilis as an indicator for targeting HIV prevention efforts generally, as well as syphilis control as a specific HIV-prevention strategy.
OBJECTIVES: Substantial biologic and epidemiologic data indicate the importance of syphilis as a potential cofactor for sexual transmission of HIV infection, but few detailed data exist on the geographic covariation of these two important sexually transmitted infections. DESIGN: HIV prevalence in childbearing women and primary and secondary (P&S) syphilis data from 29 states were examined to explore the importance of the epidemiology of syphilis as a factor in facilitating HIV transmission. METHOD: The spatial relationship between P&S syphilis and HIV infection in the health districts of 29 states was analyzed and adjusted for demographic and socioeconomic factors such as racial composition, income, housing, education levels, and access to medical services using the 1990 US census, and geographic location. RESULTS: In 29 states and the District of Colombia, 448 health districts, representing more than 75% of the US population, reported HIV prevalence rates for mothers' district of residence. The HIV seroprevalence ranged from 0 to 1258/10 000 in these health districts. The incidence of P&S syphilis from 1984-1994 in these districts ranged from 0 to 87/100 000. The P&S syphilis incidence was positively associated with the prevalence of HIV infection among childbearing women (P < 0.0001). CONCLUSIONS: Syphilis that persists in communities in the United States appears to represent a 'sentinel public health event' reflecting risk for sexual HIV transmission. These findings, along with other biologic and epidemiologic information, reinforce the importance of syphilis as an indicator for targeting HIV prevention efforts generally, as well as syphilis control as a specific HIV-prevention strategy.