Estimating how many STD cases occur is not a simple or straightforward task.
First, most STDs can be "silent," causing no noticeable symptoms. These asymptomatic infections can be diagnosed only through testing. Unfortunately, routine screening programs are not widespread, and social stigma and lack of public awareness concerning STDs often inhibits frank discussion between health care providers and patients about STD risk and the need for testing. [ASHA. Sexually Transmitted Diseases in America: How Many Cases and at What Cost? December 1998]
More than half of all people will have an STD at some point in their lifetime. 
The estimated total number of people living in the US with a viral STD is over 65 million. 
Every year, there are at least 15 million new cases of STDs, some of which are curable. [2,3]
More than $8 billion is spent each year to diagnose and treat STDs and their complications. This figure does not include HIV. 
In a national survey of US physicians, fewer than one-third routinely screened patients for STDs. 
Less than half of adults ages 18 to 44 have ever been tested for an STD other than HIV/AIDS.
Each year, one in four teens contracts an STD. 
One in two sexually active persons will contact an STD by age 25. 
About half of all new STDs in 2000 occurred among youth ages 15 to 24.  The total estimated costs of these nine million new cases of these STDs was $6.5 billion, with HIV and human papillomavirus (HPV) accounting for 90% of the total burden. 
Of the STDs that are diagnosed, only some (gonorrhea, syphilis, chlamydia, hepatitis A and B) are required to be reported to state health departments and the CDC.
One of 20 people in the United States will get infected with hepatitis B (HBV) some time during their lives.  Hepatitis B is 100 times more infectious than HIV. 
Approximately half of HBV infections are transmitted sexually.  HBV is linked to chronic liver disease, including cirrhosis and liver cancer.
It is estimated that as many as one in four Americans have genital herpes, a lifelong viral infection, yet up to 90 percent of those with herpes are unaware they have it.  With more than 50 million adults in the US with genital herpes and up to 1.6 million new infections each year, some estimates suggest that by 2025 up to 40% of all men and half of all women could be infected. [14,15,16]
Over 6 million people acquire HPV each year, and by age 50, at least 80 percent of women will have acquired genital HPV infection.  Most people with HPV do not develop symptoms. Some researchers believe that HPV infections may self-resolve and may not be lifelong like herpes. 
Cervical cancer in women, while preventable through regular Paps, is linked to high-risk types of HPV.
Each year, there are approximately 3 million new cases of chlamydia, many of which are in adolescents and young adults.  The CDC recommends that sexually active females 25 and under should be screened at least once a year for chlamydia, even if no symptoms are present.
About two-thirds of young females believe doctors routinely screen teens for chlamydia.  However, in 2003 only 30% of women 25 and under with commercial health care plans and 45% in Medicaid plans were screened for chlamydia. 
At least 15 percent of all American women who are infertile can attribute it to tubal damage caused by pelvic inflammatory disease (PID) , the result of an untreated STD. Consistent condom use reduces the risk of recurrent PID and related complications. 
Koutsky L. (1997). Epidemiology of genital human papillomavirus infection. American Journal of Medicine, 102(5A), 3-8.
American Social Health Association. (1998). Sexually transmitted diseases in America: How many cases and at what cost? Research Triangle Park, NC: American Social Health Association.
Cates W, Jr., American Social Health Association Panel. (1999). Estimates of the incidence and prevalence of sexually transmitted diseases in the United States. Sexually Transmitted Diseases, 26(Suppl. 4), S2-7.
Institute of Medicine. (1997). The hidden epidemic–Confronting sexually transmitted disease (edited by Thomas R. Eng and William T. Butler). Washington, DC: National Academy Press.
St Lawrence JS et al. (2002). STD screening, testing, case reporting, and clinical and partner notification practices: a national survey of US physicians. American Journal of Public Health, 92, 1784-1788.
Alan Guttmacher Institute. (1994). Sex and America's Teenagers. New York: Alan Guttmacher Institute.
Cates JR, Herndon NL, Schulz S L, Darroch JE. (2004). Our voices, our lives, our futures: Youth and sexually transmitted diseases. Chapel Hill, NC: University of North Carolina at Chapel Hill School of Journalism and Mass Communication.
Weinstock H, Berman S, Cates W, Jr. (2004). Sexually transmitted diseases among American youth: Incidence and prevalence estimates, 2000. Perspectives on Sexual and Reproductive Health, 36, 6-10.
Chesson HW, Blandford JM, Gift TL, Tao G, Irwin KL. (2004). The estimated direct medical cost of sexually transmitted diseases among American youth, 2000. Perspectives on Sexual and Reproductive Health, 36, 11-19.
Centers for Disease Control and Prevention. Hepatitis B Frequently Asked Questions. Updated April 1, 2005. Retrieved April 22, 2005 from http://www.cdc.gov/ncidod/diseases/hepatitis/b/faqb.htm
Centers for Disease Control and Prevention. Hepatitis B Prevention for Men Who Have Sex With Men. Online Fact Sheet. Updated April 1, 2005. Retrieved April 22, 2005 from http://www.cdc.gov/ncidod/diseases/hepatitis/msm/hbv_msm_fact.htm.
Centers for Disease Control and Prevention. Tracking the hidden epidemics, 2000: Trends in the United States. Retrieved April 22, 2005 from http://www.cdc.gov/nchstp/od/news/RevBrochure1pdfHepatitisB.htm.
Fleming DT et al. (1997). Herpes simplex virus type 2 in the United States, 1976–1994. New England Journal of Medicine, 337, 1105–1111.
Corey L & Handsfield HH. (2000). Genital herpes and public health: addressing a global problem. Journal of the American Medical Association, 283, 791-794.
Armstrong GL et al. (2001). Incidence of herpes simplex virus type 2 infection in the United States. American Journal of Epidemiology, 153, 912-920.
Fisman DN et al. (2002). Projection of the future dimensions and costs of the genital herpes simplex type 2 epidemic in the United States. Sexually Transmitted Diseases, 29, 608-622.
Centers for Disease Control and Prevention. Genital HPV Infection. Online Fact Sheet. Retrieved May 9, 2005 from http://www.cdc.gov/std/HPV/STDFact-HPV.htm.
American Social Health Association. (2005). State of the Nation 2005: Challenges facing STD prevention in youth. Research Triangle Park, NC: American Social Health Association.
National Committee for Quality Assurance. (2004). The state of health care quality: 2004. Washington, DC: NCQA.
Ness RB et al. (2004). Condom use and the risk of recurrent pelvic inflammatory disease, chronic pelvic pain, or infertility following an episode of pelvic inflammatory disease. American Journal of Public Health, 2004, 94:1327-1329.
Page last updated May 3, 2006