2
The Neglected Health and Economic Impact of STDs

Highlights

  • More than 12 million Americans, 3 million of whom are teenagers, are infected with STDs each year.
  • STDs accounted for 87 percent of all cases reported among the top ten most frequently reported diseases in 1995 in the United States.
  • Since 1980, eight new sexually transmitted pathogens have been recognized in the United States.
  • STDs may cause serious, life-threatening complications including cancers, infertility, ectopic pregnancy, spontaneous abortions, stillbirth, low birth weight, neurologic damage, and death.
  • Women and adolescents are disproportionately affected by STDs and their sequelae.
  • Reducing other STDs decreases the risk of HIV transmission.
  • Every year, approximately $10 billion is spent on major STDs other than AIDS and their preventable complications. This cost is shared by all Americans.

Sexually transmitted diseases (STDs) are a tremendous health and economic burden on the people of the United States. More than 12 million Americans are infected with STDs each year (CDC, DSTD/HIVP, 1993). In 1995, STDs accounted for 87 percent of all cases reported among the top ten most frequently reported diseases in the United States (CDC, 1996). Of the top ten diseases, five are STDs (i.e., chlamydial infection, gonorrhea, AIDS, primary and secondary syphilis, and hepatitis B virus infection).

Rates of "classical" STDs such as gonorrhea and syphilis are slowly declining in the United States, but rates of a number of STDs in the United States are higher than in some developing regions (Piot and Islam, 1994) and still far exceed those of every other developed country1 (Aral and Holmes, 1991) (Figure 2-1). For example, the reported incidence of gonorrhea in 1995 was 149.5 cases per

1  

For the purposes of this report, defined as western and northern European countries, Canada, Japan, and Australia.



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--> 2 The Neglected Health and Economic Impact of STDs Highlights More than 12 million Americans, 3 million of whom are teenagers, are infected with STDs each year. STDs accounted for 87 percent of all cases reported among the top ten most frequently reported diseases in 1995 in the United States. Since 1980, eight new sexually transmitted pathogens have been recognized in the United States. STDs may cause serious, life-threatening complications including cancers, infertility, ectopic pregnancy, spontaneous abortions, stillbirth, low birth weight, neurologic damage, and death. Women and adolescents are disproportionately affected by STDs and their sequelae. Reducing other STDs decreases the risk of HIV transmission. Every year, approximately $10 billion is spent on major STDs other than AIDS and their preventable complications. This cost is shared by all Americans. Sexually transmitted diseases (STDs) are a tremendous health and economic burden on the people of the United States. More than 12 million Americans are infected with STDs each year (CDC, DSTD/HIVP, 1993). In 1995, STDs accounted for 87 percent of all cases reported among the top ten most frequently reported diseases in the United States (CDC, 1996). Of the top ten diseases, five are STDs (i.e., chlamydial infection, gonorrhea, AIDS, primary and secondary syphilis, and hepatitis B virus infection). Rates of "classical" STDs such as gonorrhea and syphilis are slowly declining in the United States, but rates of a number of STDs in the United States are higher than in some developing regions (Piot and Islam, 1994) and still far exceed those of every other developed country1 (Aral and Holmes, 1991) (Figure 2-1). For example, the reported incidence of gonorrhea in 1995 was 149.5 cases per 1   For the purposes of this report, defined as western and northern European countries, Canada, Japan, and Australia.

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--> Figure 2-1 Rates of reported syphilis (primary and secondary cases) and gonorrhea in the United States and other developed countries, 1995. SOURCES: 1) Australia: Herceg A, Oliver G, Myint H, Andrews G, Curran M, Crerar S, et al. Annual report of the national notifiable diseases surveillance system, 1995. Communicable Diseases Intelligence, Commonwealth Department of Health and Family Services. October 14, 1996;20:440-464. Rates of primary and secondary syphilis not available; 2) Canada: JoAnne Doherty, Laboratory Center for Disease Control, Division of STD Prevention & Control, Ottawa, Ontario, Canada, personal communication, November 1996; 3) Denmark: Dr. Inga Lind, WHO Collaborating Centre for Reference and Research in Gonococci, Copenhagen, Denmark, personal communication, November 1996; 4) England: Hannah Bowers, Public Health Laboratory Services, Communicable Disease Surveillance Centre, London, England, United Kingdom, personal communication, November 1996; 5) Germany: Dr. Lyle Petersen, Robert Koch Institute, Berlin, Germany, personal communication, November 1996; 6) Sweden: Dr. Kristina Ramstedt, Swedish Institute for Infectious Disease Control, Epidemiological Department, personal communication, November 1996; 7) United States: Division of STD Prevention, Sexually transmitted disease surveillance, 1995. U.S. Department of Health and Human Services, Public Health Service. Atlanta: Centers for Disease Control and Prevention, September 1996.

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--> 100,000 persons in the United States versus 3.0 cases per 100,000 in Sweden (CDC, DSTDP, 1996; Swedish Institute for Infectious Disease Control, unpublished data, 1996). Because actual U.S. rates are estimated to be approximately twice the reported rate, the U.S. rate is 100 times the reported rate in Sweden. Similarly, the reported incidence of gonorrhea in Canada in 1995 was 18.6 cases per 100,000, or approximately 12 percent of the U.S. rate (Laboratory Centre for Disease Control, Canada, unpublished data, 1996). In addition, the rate of primary and secondary syphilis in the United States was 6.3 cases per 100,000 persons versus 0.4 cases per 100,000 persons in Canada. Therefore, rates of curable STDs, including gonorrhea, syphilis, and chancroid are many times higher in the United States than in other developed countries. The differences in rates of viral STDs between the United States and other developed countries, however, appear to be much smaller. Data for viral STDs are much more limited than for bacterial STDs, but do not suggest major differences. For example, a cohort of young Swedish women studied over a 16-year-period showed a cumulative incidence of genital herpes that was comparable to the age-specific increases in herpes simplex virus type 2 antibodies seen during the approximately the same period in U.S. women (Christenson et al., 1992; Johnson et al., 1993). Potential explanations for the observed differences between the United States and other developed countries in rates of curable STDs are presented in Chapter 3. Further, many new STDs have been discovered or have newly arisen during the antibiotic era. Of these "modern" STDs, some, including HIV infection, human papillomavirus infection, and hepatitis B virus infection, are viral infections that are incurable and are now recognized as major preventable causes of death and disability. The bacterial STDs, such as gonorrhea and syphilis, can be easily diagnosed and successfully treated; others, such as chlamydial infection, are curable but will require a much stronger, coordinated national effort to be brought under control. Broad Scope and Impact of STDs STDs affect persons of all racial, cultural, socioeconomic, and religious groups in the United States. Persons in all states, communities, and social networks are at risk for STDs. The estimated incidence and prevalence of major STDs are summarized in Table 2-1. The term "STD" is not specific for any one disease but denotes the more than 25 infectious organisms that are transmitted through sexual activity and the dozens of clinical syndromes that they cause (Appendix A). With STDs, one infectious organism does not cause one syndrome; rather, there is a matrix of infectious organisms and associated syndromes. For example, some syndromes, such as pelvic inflammatory disease, can be caused by a number of organisms, including Neisseria gonorrhoeae, Chlamydia trachomatis, and other bacteria. Urethritis (inflammation of the canal leading from the urinary bladder) in men is frequently

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--> Table 2-1 Estimated Annual Incidence and Prevalence of Selected Sexually Transmitted Diseases (STDs) in the United States, 1994 STD Incidence Prevalence Chlamydial infection 4,000,000a Not available Gonorrhea 800,000a Not available Syphilis 101,000 Not available Congenital syphilis 3,400 Not available Human papillomavirus infection 500,000-1,000,000 24,000,000 Genital herpes infection 200,000-500,000 31,000,000b Hepatitis B virus infection (sexually transmitted) 53,000a Not available AIDS 79,897c 185,000d HIV infection Not available 630,000-897,000e Chancroid 3,500 Not available Trichomoniasis 3,000,000 Not available Pelvic inflammatory disease >1,000,000f Not available NOTE: The Division of STD Prevention, CDC, is currently developing a process for systematically generating and updating incidence and prevalence estimates for specific STDs. a Number reflects reported cases to the CDC plus estimated unreported cases. b Based on Johnson RE, Nahmias AJ, Magder LS, Lee FK, Brooks CA, Snowden CB. A seroepidemiologic survey of the prevalence of herpes simplex virus type 2 infection in the United States. N Engl J Med 1989;321:7-12. However, recent data indicate a substantial recent increase in prevalence in the United States (Johnson R, Lee F, Hadgu A, McQuillan G, Aral S, Keesling S, et al. U.S. genital herpes trends during the first decade of AIDS—prevalences increased in young whites and elevated in blacks. Proceedings of the Tenth Meeting of the International Society for STD Research, August 29-September 1, 1993, Helsinki [abstract no. 22]). c Reported cases to the CDC. Source: CDC. HIV/AIDS Surveillance Report. Atlanta: Centers for Disease Control and Prevention, 1995;7(2). d Estimated prevalence of persons diagnosed with AIDS at the end of 1993. All AIDS cases including unreported cases. e Prevalence as of January 1993. Source: Rosenberg PS. Scope of the AIDS epidemic in the United States. Science 1995;270:1372-5. f Based on estimate for 1993 by Siegel (Appendix D of present report), Washington and Katz also estimated more than one million cases per year using older data (Washington AE, Katz P. Cost of and payment source for pelvic inflammatory disease. Trends and projections, 1983 through 2000 [see comments]. JAMA 1991;266:2565-9.). PRIMARY SOURCE: CDC, DSTD/HIVP. Annual Report 1994. U.S. Department of Health and Human Services, Public Health Service. Atlanta: Centers for Disease Control and Prevention, 1995. caused by gonorrhea or chlamydia but can also result from infection with ureaplasma, mycoplasma, and other organisms. Genital ulcers can result from herpes, chancroid, syphilis, or other infections. Vaginal discharge can be caused by trichomonas, bacterial vaginosis, or other infections. Syphilis and HIV infection have myriad clinical manifestations and can mimic many health conditions. In addition, common infections once considered trivial are now known to cause

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--> serious complications. For example, bacterial vaginosis, a frequent cause of vaginitis in sexually active women, was once considered to be a benign condition but has recently been shown to be associated with premature delivery, low birth weight, and pelvic inflammatory disease (Hauth et al., 1995; Hillier et al., 1995). Human papillomaviruses, originally recognized to cause warts, are now known to be important causes of several types of cancer. Routes of Transmission Epidemiological and other characteristics of eight common STDs are summarized in Appendix B. STDs are almost always transmitted from person to person by sexual intercourse.2 STDs are transmitted most efficiently by anal or vaginal intercourse, and generally less efficiently by oral intercourse. A few STDs, such as scabies, can also be transmitted without sexual intercourse via direct contact with an infected site of a sex partner. Other more important blood-borne pathogens, such as hepatitis B virus, human T-cell lymphotrophic virus type I, and HIV, are transmitted among adults not only by sexual intercourse, but also by parenteral routes—particularly among intravenous drug users through contaminated injecting drug equipment. The relative contribution of parenteral versus sexual transmission varies according to the risk behaviors of the population and other factors. In addition, pregnant women with an STD may pass their infection to infants in the uterus, during birth, or through breast-feeding. Summary of Common STDs Human Papillomavirus Infection Human papillomavirus is associated with the development of cervical and other genital and anal cancers (Koutsky et al., 1988; Reeves et al., 1989) and is prevalent across all socioeconomic groups in the United States. An estimated 24 million Americans already are infected with human papillomavirus, and as many as one million new human papillomavirus infections occur each year (CDC, DSTD/HIVP, 1995). In one study of female college students presenting for care at a university health center, genital human papillomavirus infections were five times more common than all other STDs combined (Laura Koutsky and King Holmes, University of Washington, unpublished data, 1995). 2   The term ''sexual intercourse" is used throughout this report to refer to all forms of intercourse, including vaginal, anal, and oral intercourse.

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--> Herpes Simplex Virus Infection Sexually transmitted herpes simplex virus infection is widespread in the United States and results in painful recurrent genital ulcers. The ulcers can be treated, but infection persists and ulcers may recur (Quinn and Cates, 1992). Herpes simplex virus can be transmitted to sex partners even when no genital ulcer is present (Mertz et al., 1992) and can also be transmitted from mother to infant during delivery. Approximately 200,000-500,000 new cases of genital herpes occur each year in the United States, and 31 million individuals already are infected (CDC, DSTD/HIVP, 1995). In 1990, the prevalence of antibodies to herpes simplex virus type 2 among persons 15-74 years of age was estimated at 21.7 percent (Johnson et al., 1993). This prevalence estimate suggests that at least one of every four women and one of every five men in the United States will become infected with herpes during their lifetime. Viral Hepatitis Hepatitis B virus infection is an STD with severe complications including chronic hepatitis, cirrhosis, and liver carcinoma. Of approximately 200,000 new hepatitis B virus infections in the United States each year, approximately half are transmitted through sexual intercourse (Alter and Mast, 1994; CDC, 1994b; Goldstein et al., 1996). Preliminary data from a large U.S. multisite study indicate that approximately one-third of persons with acute hepatitis B virus infections in 1995 had a history of another STD (CDC, Hepatitis Branch, unpublished data, 1996). In addition to hepatitis B, several other types of viral hepatitis can be transmitted sexually. Hepatitis A is a cause of acute hepatitis, and less than 5 percent of infections are transmitted through fecal-oral contact during sexual intercourse, mostly among men who have sex with men (CDC, 1994b; CDC, Hepatitis Branch, 1995). Hepatitis D (delta) virus is a virus that can be sexually transmitted but requires the presence of hepatitis B virus to replicate. Sexual transmission of hepatitis D virus occurs, but it is less efficiently transmitted through sexual intercourse than hepatitis B virus (Alter and Mast, 1994). Hepatitis C virus, the most common cause of non-A non-B hepatitis, causes chronic liver disease in most infected adults. The efficiency of sexual and perinatal transmission of this virus, however, seems to be low (Alter and Mast, 1994). Syphilis After sustaining a steady incidence rate during the 1970s and early 1980s, the rate of syphilis increased sharply from 1987 through 1990 (CDC, DSTDP, 1995), after which rates began to fall. This epidemic illustrates the ability of syphilis and other STDs to reemerge with alarming intensity in populations such as illicit drug users—particularly crack cocaine users—and their sex partners

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--> (Farley et al., 1990; Rolfs et al., 1990). The reemergence of syphilis in this new context rendered traditional prevention efforts less effective (Andrus et al., 1990). Gonorrhea Gonorrhea infections in the United States are becoming increasingly resistant to routine antibiotic treatment; this has resulted in increasingly expensive treatments as effective therapeutic options become more limited. As of 1976, all gonorrhea infections were curable by penicillin (Aral and Holmes, 1991). Since then, antibiotic-resistant strains have increased steadily to 2 percent of gonorrhea infections in 1987 and to 30 percent of gonorrhea infections in 1994 (CDC, DSTDP, 1995). The Gonococcal Isolate Surveillance Project of the Centers for Disease Control and Prevention (CDC) measures national trends in gonorrhea antibiotic resistance. The proportion of isolates resistant to penicillin has increased steadily since monitoring began in 1988 (CDC, DSTDP, 1995) (Figure 2-2). In 1994, approximately 30 percent of gonococcal isolates were resistant to tetracycline, penicillin, or both; these antibiotics represent traditional, effective, low-cost treatment for gonorrhea. In addition, resistance to the newer quinolone antibiotics has been documented in the Western Pacific and Southeast Asia and in several U.S. states, indicating that some currently recommended treatment regimens may soon become inadequate (CDC, 1994a; GDHR, Epidemiology and Prevention Branch, 1995). Chlamydial Infection Chlamydial genital infection is the most common bacterial STD in the United States; of the more than 4 million cases estimated to occur annually, 2.6 million cases occur among women (CDC, DSTDP, 1995). As many as 85 percent of infections in women and 40 percent of infections in men may be asymptomatic and will not be identified without screening (Fish et al., 1989; Judson, 1990; Stamm and Holmes, 1990). Uncomplicated chlamydial infections can be easily treated with antibiotics (CDC, 1993); however, primarily as a result of unrecognized and untreated cervical infections, more than one million women each year develop pelvic inflammatory disease (Rolfs et al., 1992). Impact of STDs on Women's Health Complications of STDs are greater and more frequent among women than men for a number of reasons (Wasserheit and Holmes, 1992). Women are biologically more likely to become infected than men if exposed to a sexually transmitted pathogen. STDs are also more likely to remain undetected in women, resulting in delayed diagnosis and treatment, and these untreated infections are more likely to lead to complications.

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--> Figure 2-2 Percentage of isolates resistant to antibiotics, Gonococcal Isolate Surveillance Project, 1991-1994. SOURCE: CDC, DSTDP. Sexually Transmitted Disease Surveillance 1994. U.S. Department of Health and Human Services, Public Health Service. Atlanta: Centers for Disease Control and Prevention, 1995. Many STDs are transmitted more easily from man to woman than from woman to man (Harlap et al., 1991). For example, the risk to a woman of acquiring gonorrhea from a single act of intercourse may be as high as 60 to 90 percent, while transmission from a woman to man is about 20 to 30 percent (Holmes et al., 1970; Hooper et al., 1978; Platt et al., 1983; Judson, 1990; Donegan et al., 1994). Among couples where only one partner was initially infected, the annual risk of transmission of herpes simplex virus was 19 percent from man to woman, but only 5 percent from woman to man (Mertz et al., 1992). The comparative efficiency of male-to-female versus female-to-male transmission of HIV seems to differ according to the study population (Haverkos et al., 1992). Studies in the United States (Peterman et al., 1988; Padian et al., 1991) generally have shown greater efficiency of transmission from man to woman than from woman to man, while studies in Haiti (Deschamps et al., 1996) and Europe (de Vincenzi, 1994) have shown no significant gender difference in efficiency of transmission.

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--> STDs are often silent in women, and even when symptoms of STD occur, they may not arouse suspicion of an STD. For example, 30 to 80 percent of women with gonorrhea are asymptomatic, while fewer than 5 percent of men have no symptoms (Hook and Handsfield, 1990; Judson, 1990). Similarly, as many as 85 percent of women with chlamydial infection are asymptomatic compared to 40 percent of infected men (Fish et al., 1989; Judson, 1990; Stamm and Holmes, 1990). When an STD is suspected, it is often more difficult to diagnose in a woman because the anatomy of the female genital tract makes clinical examination more difficult (Aral and Guinan, 1984). For example, a urethral swab and a Gram stain are sufficient to evaluate the possibility of gonorrhea in men, but a speculum examination of the cervix and a specific culture for gonorrhea have been required for women (Hook and Handsfield, 1990). Thus, women with gonorrhea or chlamydial infection are often not diagnosed with an STD until complications, such as pelvic inflammatory disease, occur. Even then, symptoms of pelvic inflammatory disease due to chlamydial infection may be absent or non-specific, resulting in as many as 85 percent of women delaying seeking medical care, thus increasing their risk for long-term complications (Hillis et al., 1993). Fortunately, the advent of newer tests for detecting gonococci and chlamydia in urine may permit testing women for these organisms without pelvic examination in the future, as described in Chapter 4. Once infected, women are more susceptible than men to complications of certain STDs. For example, women infected with certain types of human papillomavirus are at risk for cancers of the cervix (a relatively common malignancy), as well as cancers of the vagina, vulva, and anus; whereas heterosexual men infected with these human papillomavirus types are at risk only for cancers of the penis (a relatively uncommon malignancy). Another example is the risk of infertility caused by gonorrhea or chlamydial infection, which is much higher in women than in men. Finally, pregnant women and their infants are particularly vulnerable to complications of STD during pregnancy or parturition. Greater Risk of STDs Among Adolescents Every year, approximately 3 million American teenagers acquire an STD (CDC, DSTD/HIVP, 1993). During the past two decades, sexual intercourse among adolescents has steadily increased, resulting in an enlarging pool of young men and women at risk for STDs (CDC, 1995c). As a result, STDs, unintended pregnancies, and other health problems that result from sexual intercourse have increased among adolescents in the United States (AGI, 1994). Adolescents (10-19 years of age) and young adults (20-24 years of age) are the age groups at greatest risk for acquiring an STD, for a number of reasons: they are more likely to have multiple sex partners; they may be more likely to engage in unprotected intercourse; and their partners may be at higher risk for being infected compared to most adults (Cates, 1990; Quinn and Cates, 1992; AGI, 1994; CDC, DSTDP,

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--> 1995). Compared to older women, female adolescents and young women are also more susceptible to cervical infections, such as gonorrhea and chlamydial infection, because the cervix of female adolescents and young women is especially sensitive to infection by certain sexually transmitted organisms (Cates, 1990). In addition, adolescents and young people are at greater risk for substance use and other contributing factors that may increase risk for STDs than older persons; these issues are discussed in Chapter 3. Although overall rates of gonorrhea have been declining in the general population for over a decade, this decline has been less pronounced among adolescents than in other age groups. During 1993 and 1994, the gonorrhea rate for 15-19-year-old adolescents actually increased nearly 3 percent (CDC, DSTDP, 1995). The increase in gonorrhea among adolescents can be entirely attributed to increases in gonorrhea among female adolescents of all races, while rates of gonorrhea among male adolescents during this period leveled off. If one takes into account that not all teenagers are sexually active, the actual risk for acquiring an STD among sexually active teens is even higher than the rates themselves may suggest (Aral et al., 1988). Chlamydial infection has been consistently high among adolescents; in some studies, up to 30-40 percent of sexually active adolescent females studied have been infected (Toomey et al., 1987; Cates, 1990). In general, rates of chlamydial are at least two to four times higher than rates of gonorrhea in this age group (Washington et al., 1986; Shafer et al., 1987). Viral STDs also are becoming increasingly prevalent at younger ages as adolescents initiate sexual intercourse earlier (Moscicki et al., 1990). Cervical cancer rates and cohort mortality from cervical cancer (Krone et al., 1995; Kathleen Toomey, Georgia Department of Human Resources, unpublished data, 1996) are increasing among young women, undoubtedly a reflection of increased exposure to STDs such as human papillomavirus. Other Groups at Risk Reported STD rates in the United States vary among ethnic and racial groups (CDC, DSTDP, 1995). African Americans and Hispanic Americans have higher reported rates of chlamydial infection, gonorrhea, and syphilis than European Americans. Data on STDs among other ethnic or racial groups are more limited because of their smaller populations in the United States. Rates of certain STDs, however, among some American Indian/Alaska Native populations are high (Toomey et al., 1993). National surveillance data suggest that rates of reportable STDs, except for hepatitis B virus infection (Alter, 1991), are low among Asian Americans/Pacific Islanders compared to the general U.S. population (CDC, DSTDP, 1995). Although national surveillance data may overrepresent cases diagnosed among some racial and ethnic groups (CDC, DSTD/HIVP, 1995), the higher prevalence of some STDs among African Americans and Hispanic Americans

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--> compared to the European American population has been confirmed by serological population surveys of markers for sexually transmitted infections (Hahn et al., 1989; Johnson et al., 1993). However, serosurvey data indicate that the differences in STD rates among racial and ethnic groups are actually smaller than those suggested by national surveillance data. The reasons for the racial and ethnic differences in STD rates are unclear and complex. Possible explanations include socioeconomic status, variability in access to and utilization of health care, differences in sexual behavior, and varying risk of STDs among sexual networks (Toomey et al., 1993). Some investigators have concluded that factors other than poverty and occupational status account for the observed differences in rates of gonorrhea and chlamydial infection and that nonbehavioral factors, such as geographic segregation, may promote a higher prevalence of these STDs in certain social networks (Ellen et al., 1995). Differences in sexual behavior also cannot entirely explain the racial gap in STD rates. African Americans, for example, are generally more likely to use condoms compared to other groups (Laumann et al., 1994; Anderson et al., 1996). STDs are transmitted among all sexually active people, including heterosexual persons, men who have sex with men, and women who have sex with women (AMA, Council on Scientific Affairs, 1996). Men who have sex with men are at greater risk for many life-threatening STDs, including HIV infection, hepatitis B virus infection, and anal cancer compared to heterosexual men (AMA, Council on Scientific Affairs, 1996). Other STDs of concern among men who have sex with men include anal syphilis, urethritis, and a range of oral and gastrointestinal infections. While it is well established that men who have sex with men are at increased risk for STDs, including HIV infection, less is known about the risk of STD transmission among women who have sex with women (Kennedy et al., 1995). When compared to men who have sex with men and heterosexual persons, women who have sex only with women (and whose partners do likewise) are at substantially lower risk for acquisition of STDs. Studies show that some women who have sex with women and some bisexual women have high rates of risky behaviors, such as drug use and exchanging sex for drugs or money, as do some heterosexual women (Chu et al., 1990; Bevier et al., 1995). Although women who only have sex with women seem to be at less risk for some bacterial STDs compared to women who have sex with men (Robertson and Schachter, 1981), bacterial vaginosis and genital human papillomavirus infections are not uncommon in such women (Berger et al., 1995; Marrazzo et al., 1996). Most cases of HIV infection among women who have sex with women have been attributed to injection drug use or heterosexual intercourse (Chu et al., 1990, 1994; Cohen et al., 1993; Bevier et al., 1995). Female-to-female transmission of HIV infection seems to be relatively rare (AMA, Council on Scientific Affairs, 1996).

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--> Economic Consequences of STDs While the substantial morbidity caused by STDs is now being more widely recognized, little attention has been paid to what they cost. Limited resources and current competing health care needs, however, are forcing consideration of the economic consequences of STDs as a pivotal criterion for determining the relative urgency of this problem. By this measure also, STDs rank as a formidable health problem. Estimating STD-Associated Costs The economic burden of STDs is associated with both direct and indirect cost. Direct costs refer to expenditures for health care and represent the value of goods and services that actually were used to treat STDs or associated sequelae. These direct health care expenditures may be for either medical or nonmedical services and materials. Examples of STD-related direct costs include costs for health professionals' services (i.e., physicians, nurses, and technicians), costs of laboratory services, and cost of hospitalizations for STD (i.e., hospital accommodations and operating room). Resources used for transportation, residential care, special education, and other similar purposes are also considered direct costs. In contrast, indirect costs refer to lost productivity and represent the value of output forgone by individuals with STDs and associated disability. Indirect costs include these lost wages due to not working and/or value of household management that is not performed because of STD-related illnesses. Lost wages due to premature deaths are also considered indirect costs. The costs of a few STDs have been estimated (IOM, 1985; Washington et al., 1987; Washington and Katz, 1991), but no comprehensive, current analysis of the direct and indirect costs of STDs is available. Such information is vital to accurately depict the full magnitude of the STD problem. Moreover, only with complete STD cost data can the true benefits of investments in STD prevention be assessed. Therefore, the committee commissioned a paper to provide the basis for estimating the economic burden of STDs. Results from this analysis (conducted by Joanna Siegel at the Harvard School of Public Health) are summarized below (Table 2-5) and described in more detail in Appendix D. Total costs for a selected group of common STDs and related syndromes are estimated to be approximately $10 billion in 1994 dollars (Table 2-5). Important to note is that this rough, conservative estimate does not capture the economic consequences of several other STDs and associated syndromes such as vaginal bacteriosis, trichomoniasis, nongonococcal urethritis, mucopurulent cervicitis, lymphogranuloma venereum, molluscum contagiosum, scabies, and pediculosis pubis. Nor does this estimate include the annual cost of sexually transmitted HIV/AIDS-related illness, which is estimated to be $6.7 billion (Table 2-5). Inclusion of these costs raises the overall cost of sexually transmitted illnesses in the United

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--> Table 2-5 Estimated Costs of Selected STDs and Associated Sequelae in the United States, 1994 STD Direct Cost (1994$ millions) Total Costa (1994$ millions) Bacterialb     Chlamydial infection 1,513.9 2,013 Gonorrhea 790.6 1,051 Pelvic inflammatory disease 3,118.8 4,148 Syphilis 79.4 106 Chancroid 0.7 1 Viral     Herpes simplex virus infectionb 178.3 237 Human papillomavirus infectionc 2,877.5 3,827 Hepatitis B virus infectiond 117.0 156 Cervical cancera 554.0 737 Subtotal STDs (excluding HIV/AIDS) 7,484.4e 9,954e Sexually transmitted HIV/AIDSf 5,025.0 6,683 Total (including HIV/AIDS)a 12,509.4 16,638 a Total cost assumes a direct to indirect cost ratio of 3:1 (total cost = direct cost × 1.33); this is based on computed ratios for chlamydia of 1:1 (Washington AE, et al., 1987; see above); pelvic inflammatory disease of 2:1 (Washington AE, Katz P. Cost of and payment source for pelvic inflammatory disease. Trends and projections, 1983 through 2000 [see comments]. JAMA 1991;266:2565-9), and hepatitis B of 1:1 (Hepatitis Branch, CDC, unpublished data, 1996). b Bacterial STD, herpes simplex virus infection, and cervical cancer direct costs estimates from Joanna E. Siegel, Sc.D., Harvard School of Public Health (Appendix D of the present report). Estimate assumes 70 percent of cervical cancer is STD-related. c Human papillomavirus direct cost estimate provided by Laura Koutsky, Ph.D., Center for AIDS and STD, University of Washington, Seattle, based on data from Medicaid and other sources. Cost estimate excludes cost of HPV-related cervical cancer. d Hepatitis B virus infection direct costs based on unpublished data from the Hepatitis Branch, Centers for Disease Control and Prevention, Atlanta. Assumes half of estimated cases are sexually transmitted. e Estimate assumes that the non-pelvic-inflammatory-disease-related costs for chlamydia are approximately $462 million, or approximately 30.5 percent of total chlamydial costs (Washington AE, Johnson RE, Sanders LL. Chlamydia trachomatis infections in the United States: what are they costing us? JAMA 1987;257:2070-2), and the non-pelvic-inflammatory-disease-related costs for gonorrhea are $96.4 million or the cost of just primary treatment for gonorrhea (Appendix D of present report). f HIV/AIDS estimates provided by James G. Kahn, M.D., M.P.H., Institute for Health Policy Studies, University of California, San Francisco, based on data in Hellinger FJ. The lifetime cost of treating a person with HIV. JAMA 1993;270:474-8; CDC. HIV/AIDS surveillance report. Atlanta: Centers for Disease Control and Prevention, 1995;7(2); and Rosenberg PS. Scope of the AIDS epidemic in the United States. Science 1995;270:1372-5. Does not reflect costs of more recently recommended therapeutic regimes for this infection.

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--> States to nearly $17 billion in 1994. These cost estimates underscore the enormous burden of STDs on the U.S. economy. They also represent compelling evidence of the need for effective STD prevention programs, especially in light of the fact that a sizable proportion of the direct costs of STDs results from failure to detect and effectively manage STDs in the initial, acute stage. For example, nearly three-fourths of the $1.5 billion cost of chlamydial infections is due to preventable consequences of untreated, initially uncomplicated infections (Washington et al., 1987; Appendix D). Sources of Payment for STD-Related Costs There are limited data regarding who pays for the costs associated with STDs. A study of payment sources for pelvic inflammatory disease from 1983 through 1987 found that private insurance and public payment sources covered 41 and 30 percent, respectively, of the direct costs associated with this STD (Washington and Katz, 1991). During the study period, the proportion of payments from private insurance decreased from 54 to 41 percent. Another study in a Midwest county hospital in 1984 and 1985 showed that 54 percent of total charges associated with pelvic inflammatory disease were not reimbursed by a third-party payer or by county funding to the hospital (Nettleman and Jones, 1989). Conclusions STDs affect persons of all racial, cultural, socioeconomic, and religious groups in the United States. Persons of all sexual orientations and sexually active persons in all states, communities, and social networks are at risk for STDs. These diseases are a tremendous health and economic burden on the people of the United States. STDs predominantly affect otherwise healthy youth and young adults, but the consequences can be lifelong. This impact is largely unrecognized by the public and even some health care professionals. Severe complications of STDs include cancer, reproductive health problems, neurologic diseases, and sometimes death. Women and their infants bear a disproportionate burden of these STD-associated complications. The committee estimates that the total annual cost associated with major STDs is approximately $10 billion, which rises to $17 billion when sexually transmitted HIV infections are included. The large number of STD-related deaths and morbidity, and the high costs of managing STDs and their complications, in the United States underscores the importance of effective prevention programs for STDs. Many cases of cancer, infertility, spontaneous abortions, low birth weight, STD-related deaths, and other STD-related conditions are clearly preventable. These data justify investing in effective STD prevention programs to both reduce human suffering and contain health care costs.

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