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Sexually Transmitted Infections (STI) are measured as the chlamydia incidence (number of new cases reported) per 100,000 population.
Chlamydia is the most common bacterial STI in North America and is one of the major causes of tubal infertility, ectopic pregnancy, pelvic inflammatory disease, and chronic pelvic pain.[1,2] STIs are associated with a significantly increased risk of morbidity and mortality, including increased risk of cervical cancer, involuntary infertility, and premature death. STIs also have a high economic burden on society. The direct medical costs of managing sexually transmitted infections and their complications in the US, for example, was approximately 15.6 billion dollars in 2008.
Chlamydia incidence rates are associated with unsafe sexual activity. Chlamydia rates are readily available and reliable for nearly all counties. An important caveat in chlamydia rate reporting is that increases in reported infections may reflect true increases in disease, but may also reflect expanded screening, use of increasingly sensitive diagnostic tests, increased emphasis on case reporting from providers and laboratories, and improvement in the information systems for reporting. Communities with poor screening rates may have artificially low rates of chlamydia incidence. Last, chlamydia is only one of many STIs.
Data on sexually transmitted infections were provided by the National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP). NCHHSTP is responsible for public health surveillance, prevention research, and programs to prevent and control human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS), other sexually transmitted diseases (STDs), viral hepatitis, and tuberculosis (TB). Center staff work in collaboration with governmental and nongovernmental partners at community, state, national, and international levels, applying well-integrated multidisciplinary programs of research, surveillance, technical assistance, and evaluation.
While there is no national source for stratifying STI rates, most states publish STI data, often with age, race or gender breakdowns. When available, we link to these resources in our Finding More Data section.
 Genuis SJ, Genuis SK. Managing the sexually transmitted disease pandemic: A time for reevaluation. Am J Obstet Gynecol. 2004;191:1103-1112.  Akinbami LJ, Schoendorf KC, Kiely JL. Risk of preterm birth in multiparous teenagers. Arch Pediatr Adolesc Med. 2000;154:1101-1107. Meade CS, Ickovics JR. Systematic review of sexual risk among pregnant and mothering teens in the USA: Pregnancy as an opportunity for integrated prevention of STD and repeat pregnancy. Soc Sci Med. 2005;60:661-678. Owusu-Edusei K Jr, Chesson HW, Gift TL, Tao G, Mahajan R, Ocfemia MC, Kent CK. The estimated direct medical cost of selected sexually transmitted infections in the United States, 2008. Sex Transm Dis. 2013;40(3):197-201.
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