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Three hundred and forty million new cases of curable sexually transmitted infections (STIs) are estimated to occur each year, according to the World Health Organization (WHO).1 Despite this prevalence, STI infection rates are increasing in most countries, including the United States. In 1997, STIs were labeled a hidden epidemic by the Institute of Medicine (IOM), reflecting that this largely unrecognized U.S. public health threat has a tremendous scope.2 Although the IOM report increased awareness of STIs and stimulated progress in prevention and control of STIs, in the United States, STI rates remain the highest in the developed world, even surpassing rates in some developing countries.3


In 2004, four of the five most common reportable diseases in the United States were STIs. Approximately 65 million Americans currently live with a chronic viral STI, excluding human immunodeficiency virus (HIV);4 and one in two sexually active persons will likely contract an STI by the age of 25.5 Yet, because many STIs are asymptomatic and go undiagnosed, current surveillance systems probably underestimate the actual burden of disease. In truth, the prevalence of STIs in the United States is largely unknown; however, STIs are unquestionably a substantial health and economic burden.

Chlamydia, gonorrhea, acquired immunodeficiency syndrome (AIDS), and syphilis ranked first, second, third, and fifth among infectious diseases reportable to the National Notifiable Diseases Surveillance System (NNDSS), with chlamydia and gonorrhea alone accounting for 80% of these cases.6 Preliminary data from NNDSS for 2005 indicate similar trends.7 For non-reportable diseases such as trichomoniasis and human papillomavirus (HPV), data collection is less complete; however estimates from alternate sources suggest that both occur more frequently than chlamydia.8 The estimated incidence of selected STIs in the United States is summarized in Table 10-1.


Estimates of 2004 (by the Centers for Disease Control and Prevention [CDC] and Family Health International) reveal that approximately 18.9 million persons acquire an STI each year.8 An estimated 15 million incident cases of STIs occurred in the United States in 1996, a 25% increase from 1988. However, this trend likely reflects expansion of screening programs and ...

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