Economic Burden of Sexually Transmitted Infections: Incidence and Direct Medical Cost of Chlamydia, Gonorrhea, and Syphilis Among Illinois Adolescents and Young Adults, 2005–2006

Background: Local assessment of sexually transmitted infections (STI) magnitude and economic burden can aid in targeting resources and prevention programs. Methods: Reported cases of Chlamydia, gonorrhea, and primary and secondary syphilis (obtained from the Illinois Department of Public Health) were used to estimate the number of incident cases among persons aged 15 to 24 years, accounting for the proportion of undiagnosed and unreported cases, and sexually active population. STI costs were obtained from the published literature, and multiplied by the estimated incident cases of STIs in 2005 and 2006 to determine direct medical costs of incident infections. Incident rates per 100,000 population and costs in 2007 US dollars are estimated by age, gender, race, and county. Results: Chlamydia incidence and cost were estimated at 5030 infections per 100,000 population and $27,576,686 in 2005, and 5259 infections per 100,000 population and $28,779,734 in 2006. Gonorrhea incidence and cost were estimated at 1740 infections per 100,000 population and $7,698,135 in 2005, and 1704 infections per 100,000 population and $7,546,500 in 2006. Syphilis incidence and cost were estimated at 9.4 per 100,000 and $59,940 in 2005, and 10.4 per 100,000 population and $66,333 in 2006. Incidence and costs of all STIs were highest among women and blacks. Ten counties accounted for >80% of the estimated statewide morbidity and costs. Conclusions: Estimates of STI incidence and costs are conservative, yet represent a significant economic burden in Illinois. Focusing prevention efforts on locales with the highest STI rates may maximize effectiveness in terms of disease prevention and cost reduction.