25

Sexually Transmitted Diseases

Lead Agency:

Centers for Disease Control and Prevention

Overview

Sexually transmitted diseases (STDs) refer to the more than 25 infectious organisms transmitted primarily through sexual activity. STDs are among many related factors that affect the broad continuum of reproductive health agreed on in 1994 by 180 governments at the International Conference on Population and Development (ICPD). At ICPD, all governments were challenged to strengthen their STD programs.[1] STD prevention as an essential primary care strategy is integral to improving reproductive health.

Despite the burdens, costs, complications, and preventable nature of STDs, they remain a significant public health problem, largely unrecognized by the public, policymakers, and public health and health care professionals in the United States. STDs cause many harmful, often irreversible, and costly clinical complications, such as reproductive health problems, fetal and perinatal health problems, and cancer. In addition, studies of the worldwide human immunodeficiency virus (HIV) pandemic link other STDs to a causal chain of events in the sexual transmission of HIV infection.[2] (See Focus Area 13. HIV.)

Issues

A 1997 Institute of Medicine (IOM) report characterized STDs as “hidden epidemics of tremendous health and economic consequence in the United States” and stated, “STDs represent a growing threat to the Nation’s health and that national action is urgently needed.”3 IOM’s principal conclusion was that the United States needs to establish a much more effective national system for STD prevention, which takes into account the complex interaction between biological and social factors that sustain STD transmission in populations; focuses on preventing the disproportionate effect that STDs have on some population groups; applies proven, cost-effective behavioral and biomedical interventions; and recognizes that education, mass communication media, financing, and health care infrastructure policies must foster change in personal behaviors and in health care services.[3] (See Focus Area 23. Public Health Infrastructure.)

Biological factors. STDs are behavior-linked diseases that result from unprotected sex.3 Several biological factors contribute to their rapid spread.

Asymptomatic nature of STDs. The majority of STDs either do not produce any symptoms or signs, or they produce symptoms so mild that they often are disregarded, resulting in a low index of suspicion by infected persons who should, but often do not, seek medical care. For example, as many as 85 percent of women and up to 50 percent of men with chlamydia have no symptoms.[4], [5], [6], [7] A person infected with HIV may be asymptomatic and may transmit the disease to another person. That person may, in turn, be infected for years but remain unaware until symptoms manifest themselves.

Lag time between infection and complications. Often, a long interval—sometimes years—occurs between acquiring a sexually transmitted infection and recognizing a clinically significant health problem. Examples are cervical cancer caused by human papillomavirus (HPV), liver cancer caused by hepatitis B virus infection,[8] and infertility and ectopic pregnancy resulting from unrecognized or undiagnosed chlamydia or gonorrhea.[9] The original infection often is asymptomatic, and, as a result, people frequently do not perceive a connection between the original sexually acquired infection and the resulting health problem.

Gender and age. Women are at higher risk than men for most STDs, and young women are more susceptible to certain STDs than are older women. The higher risk is partly because the cervix of adolescent females is covered with cells that are especially susceptible to STDs, such as chlamydia.[10]

Social and behavioral factors. The spread of STDs, especially in certain vulnerable population groups, is directly affected by social and behavioral factors. Social and cultural factors may cause serious obstacles to STD prevention by adversely influencing social norms regarding sex and sexuality.

Poverty and marginalization. STDs disproportionately affect disenfranchised persons and persons who are in social networks in which high-risk sexual behavior is common and either access to care or health-seeking behavior is compromised. Some disproportionately affected groups include sex workers (people who exchange sex for money, drugs, or other goods), adolescents, persons in detention, and migrant workers.3 Without publicly supported STD services, many people in these categories would lack access to STD care.

Substance abuse, sex work, and STDsare closely connected, and substance abuse and sex work frequently are causes for arrest and detention. Studies show that comprehensive screening of incarcerated populations can be done successfully and safely within the criminal justice system.[11], [12], [13] Discussed below are several connected themes relevant to any discussion of poverty and marginalization issues.

Access to health care. Access to high-quality health care is essential for early detection, treatment, and behavior-change counseling for STDs. Often, groups with the highest rates of STDs are the same groups in which access to health services is most limited. This limitation relates to (1) lacking access to publicly supported STD clinics (present in only 50 percent of U.S. public health jurisdictions),[14] (2) having no health care coverage, (3) having coverage that imposes a copayment or deductible, or (4) having coverage that excludes the basic preventive health services that help avert STDs or their complications. (See Focus Area 1. Access to Quality Health Services.)

Substance abuse.Many studies document the association of substance abuse, especially the abuse of alcohol and drugs, with STDs.[15] At the population level, the introduction of new illicit substances into communities often can drastically alter sexual behavior in high-risk sexual networks, leading to the epidemic spread of STDs.[16] Behavioral factors that can increase STD transmission in a community include increases in the exchange of sex for drugs, increases in the number of anonymous sex partners, decreases in motivation to use barrier protection, and decreases in attempts to seek medical treatment. The nationwide syphilis epidemic of the late 1980s, for example, was fueled by increased crack cocaine use.[17] Other substances, including alcohol, may affect an individual’s cognitive and negotiating skills before and during sex, lowering the likelihood that protection against STD transmission and pregnancy will be used.

Sexual coercion. Analysis of adolescent female sexual activity reveals the frequency of coercive behaviors and brings to light that not all young women enter sexual relationships as willing partners.[18] In fact, sexual coercion is a major problem for significant numbers of young women in the United States. In 1995, 16 percent of females whose first sexual intercourse took place when they were aged 15 years or under reported that it was not voluntary.[19] This aspect of adolescent sexual behavior demands increased national and local attention, both for social justice and for health reasons. Sexual violence against women contributes both directly and indirectly to STD transmission. Directly, women experiencing sexual violence are less able to protect themselves from STDs or pregnancy. Indirectly, research demonstrates that women with a history of involuntary sexual intercourse are more likely to have voluntary intercourse at earlier ages—a known risk factor for STDs—than women who are not sexually abused.[20]

Sexuality and secrecy.Perhaps the most important social factor contributing to the spread of STDs in the United States and the factor that most significantly separates the United States from those industrialized countries with low rates of STDs is the stigma associated with STDs and the general discomfort of people in the United States with discussing intimate aspects of life, especially those related to sex.[21] Sex and sexuality pervade many aspects of the Nation’s culture, and people in the United States are fascinated with sexual matters. Paradoxically, while sexuality is considered a normal aspect of human functioning, people in the United States nevertheless are secretive and private about their sexual behavior. Talking openly and comfortably about sex and sexuality is difficult even in the most intimate relationships. One survey showed that, for married couples, about one-fourth of women and one-fifth of men had no knowledge of their partner’s sexual history.[22] In its study, IOM stated, “The secrecy surrounding sexuality impedes sexuality education programs for adolescents, open discussion between parents and their children and between sex partners, balanced messages from mass media, education and counseling activities of health care professionals, and community activism regarding STDs.”[23]

Changing sexual behaviors and sexual norms will be an important part of any long-term strategy to develop a more effective national system of STD prevention in the United States. A new sexual openness needs to become the norm to ensure that all sexual relationships are consensual, nonexploitive, and honest and to protect against disease and unintended pregnancy. This openness would allow (1) parents to talk frankly and comfortably with their children, and teachers and counselors with their students, about responsible behavior and avoiding risks (for example, abstaining from intercourse, delaying initiation of intercourse, reducing the number of sex partners, and increasing the use of effective barrier contraception), (2) sex partners to talk openly about safe behaviors, and (3) health care providers to talk comfortably and knowledgeably with patients about sexuality and sexual risk, to counsel them about risk avoidance, and to screen them regularly for STDs when indicated.[24] (See Focus Area 11. Health Communication.)

The entertainment industry, particularly television, has noticed interest in sexual themes. While people in the United States are bombarded by sexual messages and images, very little informed, high-quality STD prevention advice or discussion exists regarding contraception, sexuality, or the risks of early, unprotected sexual behavior. Popular television programs depict as many as 25 instances of sexual behaviors for every 1 instance of protected behavior or discussion about STDs or pregnancy prevention.[25]Media companies can play an important part in reshaping sexual behaviors and norms in the United States in the next decade.

Trends

STDs are common, costly, and preventable. Worldwide, an estimated 333 million cases of curable STDs occur annually.[26] In 1995, STDs were the most common reportable diseases in the United States.[27] They accounted for 87 percent of the top 10 infections most frequently reported to the Centers for Disease Control and Prevention (CDC) from State health departments. Of the top 10 infections, 5 were STDs (chlamydia, gonorrhea, AIDS, syphilis, and hepatitis B). Each year an estimated 15 million new STD infections occur in the United States, and nearly 4 million teenagers are infected with an STD.[28] The direct and indirect costs of the major STDs and their complications, including sexually transmitted HIV infection, are conservatively estimated at $17 billion annually.3

Despite recent progress toward controlling some STDs, when compared to other industrialized nations, the United States has failed to go far enough or fast enough in its national attempt to contain acute STDs and STD-related complications.3 STD rates in this Nation exceed those in all other countries of the industrialized world (including the countries of western and northern Europe, Canada, Japan, and Australia). Through a sustained, collaborative, multifaceted approach, other countries have reduced significantly the burden of STDs on their citizens, an accomplishment the United States also should strive to achieve.

Disparities

All racial, cultural, economic, and religious groups are affected by STDs. People in all communities and sexual networks are at risk for STDs. Nevertheless, some population groups are disproportionately affected by STDs and their complications.

Gender disparities. Women suffer more frequent and more serious STD complications than men do. Among the most serious STD complications are pelvic inflammatory disease (PID), ectopic pregnancy, infertility, and chronic pelvic pain.[29] Women are biologically more susceptible to infection when exposed to a sexually transmitted agent. Often, STDs are transmitted more easily from a man to a woman.[30] Acute STDs (and even some complications) often are very mild or are completely asymptomatic in women. STDs are more difficult to diagnose in women due to the physiology and anatomy of the female reproductive tract. This combination of increased susceptibility and “silent” infection frequently can result in women being unaware of an STD, which results in delayed diagnosis and treatment.

STDs in pregnant women can cause serious health problems or death to the fetus or newborn.[31] Sexually transmitted organisms in the mother can cross the placenta to the fetus or newborn, resulting in congenital infection, or these organisms can reach the newborn during delivery, resulting in perinatal infections. Regardless of the route of infection, these organisms can permanently damage the brain, spinal cord, eyes, auditory nerves, or immune system. Even when the organisms do not reach the fetus or newborn directly, they can significantly complicate the pregnancy by causing spontaneous abortion, stillbirth, premature rupture of the membranes, or preterm delivery.[32] For example, women with bacterial vaginosis are 40 percent more likely to deliver a preterm, low birth weight infant than are mothers without this condition.[33], [34] (See Focus Area 16. Maternal, Infant, and Child Health.)

Age disparities. For a variety of behavioral, social, and biological reasons, STDs also disproportionately affect adolescents and young adults.[35] In 1997, females aged 15 to 19 years had the highest reported rates of both chlamydia and gonorrhea among women; males aged 20 to 24 years had the highest reported rates of both chlamydia and gonorrhea among men.[36] The herpes infection rate of white youth aged 12 to 19 years increased nearly fivefold from the period 1976–80 to the period 1988–94.[37] Indeed, because not all teenagers are sexually active, the actual rate of STDs in teens is probably higher than the observed rates suggest.10 There are several contributing factors:

Racial and ethnic disparities. Certain racial and ethnic groups (mainly African American and Hispanic populations) have high rates of STDs, compared with rates for whites. Race and ethnicity in the United States are risk markers that correlate with other fundamental determinants of health status, such as poverty, limited or no access to quality health care, fewer attempts to get medical treatment, illicit drug use, and living in communities with a high number of cases of STDs. National surveillance data may overrepresent STDs in racial and ethnic groups that are more likely to receive STD services from public-sector STD clinics where timely and complete illness reporting is generally the rule. However, studies using random sampling techniques document higher rates of STDs in marginalized populations, particularly African Americans as compared with whites.37 Surveillance data from 1997 show:36

Finally, young heterosexual women, especially minority women, are increasingly acquiring HIV infection and developing AIDS. In 1998, 41 percent of reported AIDS cases in persons aged 13 to 24 years occurred in young women, and more than four of every five AIDS cases reported in women occurred in certain racial and ethnic groups (mostly African American or Hispanic).[40] The U.S. spread of HIV infection through heterosexual transmission closely parallels other STD epidemics.2

Compelling worldwide evidence indicates that the presence of other STDs increases the likelihood of both transmitting and acquiring HIV infection.2 Prospective epidemiologic studies from four continents, including North America, have repeatedly demonstrated that when other STDs are present, HIV transmission is at least two to five times higher than when other STDs are not present. Biological studies demonstrate that when other STDs are present, an individual’s susceptibility to HIV infection is increased, and the likelihood of a dually infected person (having HIV infection and another STD) infecting other people with HIV is increased. Conversely, effective STD treatment can slow the spread of HIVat the individual and community levels.

Opportunities

Prevention opportunities arise from an understanding of STD transmission dynamics. The rate of STD infection in a population is determined by the interaction of three principal factors:[41], [42]

Effective STD prevention requires effective population-level and individual-level interventions that can alter the natural course of these factors. IOM advised in its report, “Use of available information and interventions could have a rapid and dramatic impact on the incidence and prevalence of STDs in the United States. Many effective and efficient behavioral and biomedical interventions are available.”3

Behavioral interventions can be brought to bear on exposure, transmission, and duration factors. They help persons abstain from sexual intercourse, delay initiation of intercourse, reduce the number of sex partners, and increase the use of effective physical barriers, such as condoms, or emerging chemical barriers, such as microbicides. Further attention must be given to helping parents become better at imparting STD information. Currently, a small percentage of adolescents receive STD prevention information from parents.[43] Schools are the main source of STD information for most teenagers,43 indicating that school-based interventions can play a significant role in informing young people about STD exposure and transmission issues and in motivating them to modify their behaviors.43 (See Focus Area 7. Educational and Community-Based Programs.) Both school-based health information and school-based health service programs are potentially beneficial to young persons.[44]

Mass media campaigns have been effective in bringing about significant changes in awareness, attitude, knowledge, and behaviors for other health problems, such as smoking.[45] National communication efforts are needed to help overcome widespread misinformation and lack of awareness about STDs.

Biomedical interventions can affect aspects of transmission and duration factors. Vaccines minimize the probability of infection, disease, or both, after exposure (transmission). While vaccines for some STDs are in various stages of development, the only effective and widely available STD vaccine is for hepatitis B.[46], [47] Unfortunately, hepatitis B vaccine coverage remains minimal, especially in high-risk groups, mainly due to a lack of awareness on the part of health care providers, limited opportunities to reach high-risk youth in traditional health care settings, and limited financial support for wide-scale implementation of this effective intervention. (See Focus Area 14. Immunization and Infectious Diseases.)

Correct and consistent condom use decreases STD transmission.[48] While condom use has been on the rise in the United States over the past few decades,[49] women who use the most effective forms of contraception (sterilization and hormonal contraception) are less likely to use condoms for STD prevention.[50], [51], [52] IOM stated in its report, “Because no single method of preventing STDs or pregnancy confers the maximum level of protection against both conditions, use of dual protection—that is, a condom and another effective contraceptive for pregnancy—is especially important. Not clear, however, is how well the public understands the need for dual protection against STDs and pregnancy.”3 Dual methods could prevent unwanted pregnancy and STDs.[53] Yet most sexually active young people do not employ this strategy.[54] See Focus Area 9. Family Planning.)

Identifying and treating partners of persons with curable STDs to break the chain of transmission in a sexual network always have been integral to organized control programs.[55] Early antimicrobial prophylaxis of the exposed partner reduces the likelihood of transmission and thwarts infection. With partner treatment, the initially infected person benefits from a reduced risk of reinfection from an untreated partner, and the partner avoids acute infection and its potential complications. Future sex partners are protected by treating partners; thus, this treatment strategy also benefits the community.

Active partner notification and partner treatment generally have been the responsibility of personnel in public STD clinics. New approaches for getting more partners treated are being assessed both in traditional and nontraditional STD treatment settings. One approach actively involves initially infected patients in the process of referring their partners for evaluation and treatment.[56] Another approach uses new techniques to assess sexual networks in outbreak situations in order to identify infected patients and their partners more quickly.[57] Because most STD care in the United States is delivered in the private sector, private health care providers, managed-care organizations, and health departments need to work together to overcome barriers to rapid and effective treatment of the nonplan sex partners of health plan members.

Screening and treatment of STDs affect both transmission and duration factors. For curable STDs, screening and treatment can be cost-effective, or even cost-saving, in altering the period during which infected persons can infect others. Screening for STDs clearly meets the criteria for an effective preventive intervention.[58] For STDs that frequently are asymptomatic, screening and treatment benefit those who are likely to suffer severe complications (especially women) if infections are not detected and treated early.[59] For example, in a randomized controlled trial conducted in a large managed-care organization, chlamydia screening reduced by 56 percent new cases of subsequent pelvic inflammatory disease in a screened group.[60] Selective screening for chlamydia in the Pacific Northwest reduced the burden of disease in the screened population by 60 percent in 5 years.[61]

When combined with a new generation of sensitive and rapid diagnostic tests, some of which can be performed on a urine specimen, STD screening of specific high-risk populations in nontraditional settings appears to be a promising control strategy that expands access to underserved groups.[62] The success of screening programs will depend on the availability of funds, the willingness of communities and institutions to support them, and the availability of well-trained health care providers and of well-equipped and accessible laboratories.

Terminology

(A listing of abbreviations and acronyms used in this publication appears in Appendix H.)

Bacterial and protozoal STDs: Refer to curable sexually transmitted infections caused by Chlamydia trachomatis (chlamydia), Neisseria gonorrhoeae (gonorrhea), Treponema pallidum (syphilis), Haemophilus ducreyi (chancroid), Trichomonas vaginalis (trichomoniasis), bacterial vaginosis, and other organisms.

Congenital syphilis: A condition in a fetus or newborn caused by infection with the syphilis bacteria from an untreated mother. Infected newborns show a wide spectrum of clinical signs, and only severe cases are clinically apparent at birth. Severe illness or death can result after birth if the newborn is not treated.

Fertility problems: Refer to the standard medical definitions of infertility (have not used contraception and have not become pregnant for 12 months or more) or impaired fecundity (women reporting no sterilizing operation and classified as finding it difficult or impossible to get pregnant or carry a baby to term).

Provider referral: Formerly called contact tracing, the process whereby health department personnel directly and confidentially notify the sex partners of infected individuals about their exposure to a sexually transmitted disease for the purposes of education, counseling, and referral to health care services.

STD complications: Refer to serious health problems that occur following an acute bacterial or viral STD. Among the most serious of these complications:

Cancer: Includes cervical cancer and its precursors (due to some strains of human papillomavirus) and liver cancer that can result after chronic infection with hepatitis B virus.

Infection of a fetus or newborn: Includes conditions such as congenital syphilis, neonatal herpes, HIV infection, eye infections, and pneumonia.

Pelvic inflammatory disease (PID): Can cause permanent damage to the female reproductive tract and lead to ectopic pregnancy, infertility, or chronic pelvic pain.

Preterm birth: Can result from maternal infection.

Sexually transmitted HIV infection: Can be facilitated by the presence of an inflammatory or ulcerative STD in one or both sex partners.

Syphilis elimination: Refers to the elimination of sustained domestic transmission of syphilis. Term means that there is no continuing transmission of the disease within a community or jurisdiction and absence of transmission within a jurisdiction except within 90 days of report of an imported case.

Viral STDs: Refer to the sexually transmitted viral infections—HIV infection, genital herpes, and HPV infection. Initial infections with these organisms may be asymptomatic or may cause only mild symptoms. Hepatitis B virus and hepatitis C virus can be transmitted through sexual activity.

References

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