sexually transmitted disease

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Definition

Sexually transmitted disease (STD) is a term used to describe more than 20 different infections that are transmitted through exchange of semen, blood, and other body fluids; or by direct contact with the affected body areas of people with STDs. Sexually transmitted diseases are also called venereal diseases.

Description

The Centers for Disease Control and Prevention (CDC) has reported that 85% of the most prevalent infectious diseases in the United States are sexually transmitted. The rate of STDs in this country is 50 to 100 times higher than that of any other industrialized nation. One in four sexually active Americans will be affected by an STD at some time in his or her life.

About 12 million new STD infections occur in the United States each year. One in four occurs in someone between the ages of 16 and 19. Almost 65% of all STD infections affect people under the age of 25.

STDs can have very painful long-term consequences as well as immediate health problems. They can cause:

• birth defects
• blindness
• bone deformities
• brain damage
• cancer
• heart disease
• infertility and other abnormalities of the reproductive system
• mental retardation
• death

Some of the most common and potentially serious STDs in the United States include:

• Chlamydia. This STD is caused by the bacterium Chlamydia trachomatis, a microscopic organism that lives as a parasite inside human cells. Although over 526,000 cases of chlamydia were reported in the United States in 1997, the CDC estimates that nearly three million cases occur annually because 75% of women and 50% of men show no symptoms of the disease after infection. Approximately 40% of women will develop pelvic inflammatory disease (PID) as a result of chlamydia infection, a leading cause of infertility.
• Human papillomavirus (HPV). HPV causes genital warts and is the single most important risk factor for cervical cancer in women. Over 100 types of HPV exist, but only about 30 of them can cause genital warts and are spread through sexual contact. In some instances, warts are passed from mother to child during childbirth, leading to a potentially life-threatening condition for newborns in which warts develop in the throat (laryngeal papillomatosis).
• Genital herpes. Herpes is an incurable viral infection thought to be one of the most common STDs in this country. It is caused by one of two types of herpes simplex viruses: HSV-1 (commonly causing oral herpes) or HSV-2 (usually causing genital herpes). The CDC estimates that 45 million Americans (one out of every five individuals 12 years of age or older) are infected with HSV-2; this number has increased 30% since the 1970s. HSV-2 infection is more common in women (one out of every four women) than men (one out of every five men) and in African Americans (45.9%) than Caucasians (17.6%).
• Gonorrhea. The bacterium Neisseria gonorrhoeae is the causative agent of gonorrhea and can be spread by vaginal, oral, or anal contact. The CDC reports that approximately 650,000 individuals are infected with gonorrhea each year in the United States, with 132.2 infections per 100,000 individuals occurring in 1999. Approximately 75% of American gonorrhea infections occur in persons aged 15 to 29 years old. In 1999, 75% of reported gonorrhea cases occurred among African Americans.
• Syphilis. Syphilis is a potentially life-threatening infection that increases the likelihood of acquiring or transmitting HIV. In 1998, the CDC reported approximately 38,000 cases of syphilis in the United States; this included 800 cases of congenital syphilis. Congenital syphilis causes irreversible health problems or death in as many as 40% of all live babies born to women with untreated syphilis.
• Human immunodeficiency virus (HIV) infection. In 2000, the CDC reported that 120,223 people in the United States are HIV-positive and 426,350 are living with AIDS. In addition, approximately 1,000-2,000 children are born each year with HIV infection. It is also estimated that 33 million adults and 1.3 million children worldwide were living with HIV/AIDS as of 1999 with 5.4 million being newly infected that year. As of 2001, there is no cure for this STD.

STDs affect certain population groups more severely than others. Women, young people, and members of minority groups are particularly affected. Women in any age bracket are more likely than men to develop medical complications related to STDs. With respect to racial and ethnic categories, the incidence of syphilis is 60 times higher among African Americans than among Caucasians, and four times higher in Hispanics than in Anglos. According to the CDC, in 1999 African Americans accounted for 77% of the total number of gonorrhea cases and nearly 46% of all genital herpes cases.

— Maureen Haggerty

For more information on sexually transmitted disease, visit Britannica.com.

Infections that are acquired and transmitted by sexual contact. Although virtually any infection may be transmitted during intimate contact, the term sexually transmitted disease is restricted to conditions that are largely dependent on sexual contact for their transmission and propagation in a population. The term venereal disease is literally synonymous with sexually transmitted disease but traditionally is associated with only five long-recognized diseases (syphilis, gonorrhea, chancroid, lymphogranuloma venereum, and donovanosis). Sexually transmitted diseases occasionally are acquired nonsexually (for example, by newborn infants from their mothers, or by clinical or laboratory personnel handling pathogenic organisms or infected secretions), but in adults they are virtually never acquired by contact with contaminated intermediaries such as towels, toilet seats, or bathing facilities. However, some sexually transmitted infections (such as human immunodeficiency virus infection, viral hepatitis, and cytomegalovirus infection) are transmitted primarily by sexual contact in some settings and by nonsexual means in others. See also Gonorrhea; Syphilis.

The sexually transmitted diseases may be classified in the traditional fashion, according to the causative pathogenic organisms, as follows:

Bacteria

     Chlamydia trachomatis

     Neisseria gonorrhoeae

     Treponema pallidum

     Mycoplasma genitalium

     Mycoplasma hominis

     Ureaplasma urealyticum

     Haemophilis ducreyi

     Calymmatobacterium granulomatis

     Salmonella species

     Shigella species

     Campylobacter species

Viruses

     Human immunodeficiency viruses (types 1 and 2)

     Herpes simplex viruses (types 1 and 2)

     Hepatitis viruses B, C, D

     Cytomegalovirus

     Human papillomaviruses

     Molluscum contagiosum virus

     Kaposi sarcoma virus

Protozoa

     Trichomonas vaginalis

     Entamoeba histolytica

     Giardia lamblia

     Cryptosporidium and related species

Ectoparasites

     Phthirus pubis (pubic louse)

     Sarcoptes scabiei (scabies mite)

Sexually transmitted diseases may also be classified according to clinical syndromes and complications that are caused by one or more pathogens as follows:

1. Acquired immunodeficiency syndrome (AIDS) and related conditions

2. Pelvic inflammatory disease

3. Female infertility

4. Ectopic pregnancy

5. Fetal and neonatal infections

6. Complications of pregnancy

7. Neoplasia

8. Human papillomavirus and genital warts

9. Genital ulcer-inguinal lymphadenopathy syndromes

10. Lower genital tract infection in women

11. Viral hepatitis and cirrhosis

12. Urethritis in men

13. Late syphilis

14. Epididymitis

15. Gastrointestinal infections

16. Acute arthritis

17. Mononucleosis syndromes

18. Molluscum contagiosum

19. Ectoparasite infestation

Most of these syndromes may be caused by more than one organism, often in conjunction with nonsexually transmitted pathogens. They are listed in the approximate order of their public health impact.

Sexually transmitted diseases were previously called ‘venereal diseases’, of which there were three: syphilis, gonorrhoea, and chancroid. Over time, but particularly during the second half of the twentieth century, the range of diseases spread by sexual contact have increased considerably, and include infection by a variety of organisms, particularly bacteria and viruses, of which the newest is the Human Immunodeficiency Virus, causing AIDS (see table).

Currently, the geographical distribution of the sexually transmitted diseases (STDs) varies in number and type of condition. The World Health Organisation (WHO) estimates 333 million new infections per year (excluding HIV/AIDS). The major focus is South and South-East Asia, with an estimated 150 million new cases in 1995, and sub-Saharan Africa, with 65 million. In the developing world, the commonest diseases are gonorrhoea, syphilis, chancroid, and HIV infection, whereas in developed countries they are chlamydial infections, non-specific urethritis, genital warts, and herpes.

The STDs are important because of their complications and social stigma. The most serious sequelae occur in women, and are pelvic inflammatory disease (infection in the fallopian tubes) and ectopic pregnancy (pregnancy in the tubes), but the infections also increase the risk of stillbirth and prematurity, and can affect the new-born baby. In sub-Saharan Africa, 50% of cases of infertility can be attributed to prior tubal infection, usually with gonorrhoea or chlamydia.

The diseases and their features

The three most common presenting symptoms of STDs are urethral discharge, genital ulceration, and vaginal discharge. Whereas the first two are usually due to an STD, vaginal discharge is not. Most women have a physiological vaginal discharge, which can vary from day to day, and can also be related to their menstrual cycle. It can be due to other infections, such as candida (thrush), which are not usually sexually transmitted. Pointers to the possibility that a vaginal discharge is due to an STD are development of symptoms after a recent partner change, recent multiple sexual contacts, symptoms that are recurrent or persistent, and symptoms in the woman's partner. Finally, there may be general symptoms such as abdominal pain, menstrual problems, or pain on intercourse.

Gonorrhoea, non-specific genital infection, and chlamydia In heterosexual men, these conditions give rise to discharge from the penis, 3-14 days after exposure. In homosexual men, the rectum can be infected, but in many incidences the patient is unaware of this unless they attend a clinic for a routine check-up, or at the request of a partner who develops symptoms. In women, these three conditions can often be without specific symptoms, especially since vaginal discharge is common. These infections are particularly important in women because of the complication of pelvic inflammatory disease; if this arises, it usually causes abdominal pain, perhaps with menstrual disturbances, and pain on intercourse. Women may only become aware of their infection when their male partner develops problems. Gonorrhoea can be treated with penicillin, and non-specific genital infection and chlamydia with tetracycline.

Genital warts — small lumps around the genital regions — have become increasingly common. They have a very long incubation period after exposure (anything up to 6 months). Treatment is straightforward, by freezing or applying acidic substances such as podophyllin. Warts tend to recur. It is important that they are treated, particularly in women, where there is a possible association between some types of warts and the later development of carcinoma of the cervix. All women with genital warts should have regular cervical smears.

Genital herpes is a viral condition with a short incubation period of approximately 3-7 days. If it is a first attack, the symptoms can be particularly severe, with pain, and blisters breaking down into sores, which sometimes can be extensive. Occasionally patients may have a temperature and headache, and feel generally unwell. There are two types of herpes simplex virus. Herpes type 1 normally causes cold sores, but oral-genital contact can transmit this from the lips to the genital area, therefore one should avoid this type of contact with people during the time that they have cold sores. There is no cure for this condition, and it tends to recur, but with unpredictable frequency from patient to patient. Pregnant women can pass herpes on to the baby at the time of delivery, so they should be under specialist care.

Syphilis is now very uncommon in the UK. Primary syphilis occurs after an incubation period of about 9-90 days. Usually a solitary, painless ulcer appears at the site of exposure (penis, vulva, rectum, etc.). This will heal without treatment. Secondary syphilis appears 4-8 weeks later, in the form of a widespread rash, mainly on the shoulders, chest, back, abdomen, and arms. Tertiary syphilis occurs any time from 3-20 years after exposure, with complications affecting the central nervous system and heart.

Candidiasis, trichomonas, and bacterial vaginosis cause vaginal discharge, and are not usually sexually transmitted.

Genital ulcers are not necessarily due to STD. In Britain the commonest causes are genital herpes and syphilis, but in tropical countries there are other conditions commonly causing genital ulceration.

HIV and AIDS Even though North America and Europe experienced the first impact of the AIDS epidemic, infections with HIV are now seen throughout the world, with the focus having switched to developing/resource-poor countries. WHO estimate that, by the end of 2000, 36.1 million people were living with HIV/AIDS, and that 5.3 million new infections occurred during that year. At the time of writing, 90% of all infections occur in developing countries and continents, with the major brunt of the epidemic in sub-Saharan Africa (22.5 million cases), and south and south-east Asia (6.7 million cases).

It is now realized that cases of AIDS were first seen in central Africa in the 1970s, even though at that time it was not recognized as such. Current surveys from some African countries show that the level of infection is high amongst certain groups: in 50-90% of prostitutes and 30% of those attending departments for STDs and antenatal clinics. The advent and increase of HIV infection since the 1980s has highlighted the importance of infections spread by the sexual route. It has also been recognized that the presence of a sexually transmitted disease, particularly (a) genital ulcer(s) and/or a vaginal/urethral discharge, can enhance both the acquisition and transmission of HIV by increased shedding of the virus within and from the genital tract.

The most common mode of transmission of this virus throughout the world is by sexual intercourse, vaginal or anal. Other methods of transmission are through the receipt of infected blood or blood products, semen, or donated organs; and through the sharing or re-use of contaminated needles by injecting drug users, or for therapeutic procedures. Also, transmission from mother to child can occur, in the womb, possibly at birth, or through breast milk.

Acute infection with HIV usually passes unnoticed, although there may sometimes be fever, swollen lymph nodes, muscular pain, and a rash. Most patients are unaware of their infection unless they are tested. The antibody test carried out on blood can take approximately three months to become positive (the window period). In view of this, patients are encouraged to delay being tested after possible exposure. Chronic infection follows and again the patient may not be aware that they are infected — or they may have non-specific symptoms such as fever, night sweats, diarrhoea, and weight loss. The time between infection with HIV and developing AIDS can be very long: on average about 8-9 years. Once a patient develops AIDS, they can have tumours and/or infections in various parts of the body. There is no cure for AIDS, but the infections can be treated, and new antiviral agents against HIV are now more powerful, and may alter the medical history and life expectancy of those infected.

Control of sexually transmitted diseases is served in the UK by a network of specialist clinics: departments of Sexually Transmitted Diseases or Genitourinary Medicine clinics. The image of such clinics has changed considerably; they have become more friendly, with far less associated stigma. Most people attend without medical referral, and because the remit of these clinics has extended in recent decades, many use them for check-ups, screening for HIV, and for gynaecological problems or contraceptive advice. In developing countries, such specialist services do not usually exist, and sexually transmitted diseases are normally managed in non-specialist services, usually in rural primary health centres by non-medical staff.

Prevention of STDs involves primary and secondary approaches. Primary prevention aims to educate individuals about the advantages of discriminate and safe sex (prevention by the use of condoms), about the symptoms of the common sexually transmitted diseases, and about how to seek care for them. It is also important to point out that some conditions may cause no symptoms, so that regular check-ups are advised for those who often change their partners.

Secondary prevention aims to encourage people to seek care without delay once the symptoms of a disease are recognized, to stop sexual intercourse until medical advice has been sought, and to adhere to the advice and treatment given. The final aspect of control is the tracing of the sexual contacts of the infected patient, who may have infection without being aware of it.

— M. W. Adler

Bibliography

• Adler, M. W. (1980). The terrible peril — a historical perspective on the venereal diseases. British Medical Journal, 281, 206-11.
• Adler, M. W. (1997). The ABC of AIDS, (4th edn). BMJ Publications, London.
• Adler, M. W. (1999). The ABC of sexually transmitted diseases, (4th edn). BMJ Publications, London

Definition

Sexually transmitted diseases (STDs) are viral and bacterial infections passed from one person to another through sexual contact.

Description

Adolescence is a time of opportunities and risk when many health behaviors are established. Although many of these behaviors are health-promoting, some are health-compromising, resulting in increasingly high rates of adolescent morbidity and mortality. For example, initiation of sexual intercourse and experimentation with alcohol and drugs are normative adolescent behaviors. However, these behaviors often result in negative health outcomes such as the acquisition of STDs. As a consequence of STDs, many adolescents experience serious health problems that often alter the course of their adult lives, including infertility, difficult pregnancy, genital and cervical cancer, neonatal transmission of infections, and AIDS (acquired immunodeficiency syndrome).

Examples of STDs with high prevalence among sexually-active adolescents include:

• Gonorrhea: Caused by the bacteria Neisseria gonorrhoeae, gonorrhea infects the reproductive tract of women, causing pelvic inflammatory disease (PID), a major cause of infertility. The bacteria are found in vaginal secretions and semen.
• Chlamydia: The bacteria that causes chlamydia, Chlamydia trachomatis, trigger inflammation of the reproductive tract, leading to PID in women and epididymitis (inflammation of the epididymis) in men.
• Syphilis: Treponema pallidum is the bacteria that causes syphilis. The course of syphilis is broken down into four distinct segments: primary syphilis, occurring within a few weeks or months of initial exposure; secondary syphilis, occurring generally between six weeks and six months of initial exposure; latent syphilis, an asymptomatic period which may stretch for years; and late syphilis, the most serious stage. If left untreated, syphilis can infect a number of organ systems and cause serious complications.
• Herpes simplex virus: Two different types of HSV (HSV-1 and HSV-2) cause lesions on the genitals, although HSV-2 is associated with the majority of cases. (HSV-1 is most commonly associated with oral lesions, or "cold sores.")
• Human papillomavirus (HPV): HPV causes condylomata acuminata, more commonly known as venereal warts or genital warts. The warts may affect any of the external and internal genital organs in men and women.
• Human immunodeficiency virus (HIV). HIV is the causative agent of acquired immune deficiency syndrome (AIDS), a potentially fatal condition in which the immune system fails and the individual becomes prone to frequent and unusual infections.

Transmission

The mode of transmission varies among the different sexually transmitted diseases. Some bacteria or virus are found in vaginal secretions or semen (e.g. HIV and gonorrhea), while others are shed from the skin of and around the genitals (e.g. HSV and HPV). Infection typically occurs during sexual intercourse or when the genitals come into close contact. Infection may also occur during oral sex, such as transmission of HSV from an oral lesion to the genitals or vice versa, or transmission of HIV from genital secretions through a cut in the mouth. STDs may be transmitted during nonconsensual sex acts such as rape or molestation.

The transmission of many STDs is more efficient from men to women than from women to men. For example, with just one unprotected sexual encounter with an infected partner, a woman is twice as likely as a man to acquire gonorrhea or chlamydia. In addition, different STDs have different rates of transmissibility. For example, with one exposure of unprotected sexual intercourse, a woman has a 1 percent chance of acquiring HIV, a 30 percent chance of acquiring herpes, and 50 percent chance of contracting gonorrhea if her partner is infected.

Demographics

STDs among sexually experienced adolescents occur at alarmingly high rates. One-fourth of the estimated 12 million new cases reported annually occur among adolescents between 15 and 19 years of age. Moreover, since many STDs are asymptomatic, they are often undiagnosed and untreated, thus increasing their potential for proliferation among adolescents.

Gonorrhea and chlamydia, the most prevalent bacterial STDs, disproportionately affect adolescents. The rates of gonorrhea in adolescents ages 15 to 19 years declined between 1990 and 2004, but in the early 2000s they continue to be higher than rates for any five-year age group between 20 and 44 years, particularly among women and African Americans.

Numerous prevalence studies for chlamydia have shown rates to be highest among adolescents and young adults under 25 years of age, many of whom are minorities. Rates of chlamydia reported by gender indicate that women, overall, have higher rates than men due in large part to increased efforts in screening women for asymptomatic chlamydial infections. The low rates of chlamydia for men suggest that the sexual partners of women diagnosed with chlamydia are not being diagnosed or treated. Chlamydia has been detected in more than 10 percent of sexually experienced women during screening.

While rates of syphilis declined between 1990 and 2004, the disease continues to be an important cause of sexually transmitted infection. The rate of syphilis infection among adolescents ages 15 to 19 is 1.3 per 100,000 population for males and 2.2 per 100,000 population for females. For comparison, the syphilis rates among males 20 to 24 is 5.5 per 100,000, and among females of the same age, 3.3 per 100,000.

HSV and HPS occur at alarming rates among sexually experienced adolescents. Studies indicate that one in six Americans is infected with HSV-2, reflecting a ninefold increase between 1975 and 2005. Prevalence of HSV-2 in adolescents and young adults varies by the demographic and behavioral characteristics of the populations studied as well as the diagnostic methods used. As of the early 2000s approximately 4 percent of Caucasians and 17 percent of African Americans are infected with HSV-2 by the end of their teenage years. One study of young pregnant women of low income status found an HSV-2 infection rate of 11 percent in women 15 to 19 years of age and 22 percent in women 25 to 29 years of age.

In 2002, there were 4,785 reported cases of AIDS among teenagers between the ages of 13 and 19, more than double the 1994 figures. Most adolescents with AIDS were infected as a result of high risk sexual and substance use behaviors. Among adolescents ages 13 to 19 years infected with HIV, 49 percent are male and 51 percent are female. Studies also indicate that African-American and Latino teens are overrepresented among persons with AIDS relative to their proportion in the population. Although these epidemiological statistics on AIDS in the United States provide a descriptive overview of the prevalence and patterns of HIV exposure in adolescents, the extent of asymptomatic HIV infection remains largely unknown.

Causes and Symptoms

The chance for adolescents of getting and transmitting STDs is affected by complex interrelationships between key factors (sociodemographic, biologic, psychosocial, and behavioral). For example, many STD-related risk markers (e.g. age, gender, race/ethnicity) correlate with more fundamental determinants of risk status (e.g., access to health care, living in communities with high prevalence of STDs) to influence adolescents' risk for STDs.

Developmental factors such as pubertal timing, self-esteem, and peer affiliation may also increase their risk of exposure to STDs. An assessment of these interrelationships is critical to preventing and controlling STDs in adolescents. Moreover, since behavior is the common means by which STDs occur, an important first step in fighting STDs is to understand the prevalence and patterns of risk behaviors as well as the psychosocial context in which these behaviors occur.

Behavioral Factors

Although biologic factors play an important role in the transmission of STDs, it is also the health-risking behaviors of adolescents that place them at increased risk for exposure to STDs. Behavioral risk factors include the age of sexual activity, number of sexual partners, use of contraceptives, and use of alcohol and drugs.

SEXUAL ACTIVITY. Early initiation of sexual intercourse has been associated with high-risk sexual activities, including ineffective use of contraceptives, multiple sex partners over a short period of time, high-risk sex partners, and acquisition of STDs and their consequences of cervical cancer and dysplasia. The average age of first sexual intercourse is between 16 and 17 years for adolescent men and between the age of 17 and 18 years for adolescent women, and has been found to be as young as age 12 in some high-risk populations. Research on adolescents' decision to initiate sexual intercourse indicates an interaction between biological and social factors. However, much remains unknown about the interactions between hormones, behavior, and social factors.

The Youth Risk Behavior Surveillance System (YRBSS), a self-reported survey of a national representative sample of high school students in grades nine to 12, indicated that in 2003, 46.7 percent of the students reported having had sex. By grade level, the rates were 32.8 percent for ninth grade, 44.1 percent for tenth grade, 53.2 percent for eleventh grade, and 61.6 percent for twelfth grade. Approximately 7.4 percent of students reported having sex for the first time before age 13. Prevalence rates of sexual experience differed by race/ethnicity and gender. African-American students were significantly more likely (73.8% of males and 60.9% of females) than Caucasian (40.5% of males and 43.0% of females) and Hispanic (56.8% of males and 46.4% of females) students to have engaged in sexual intercourse. Moreover, data from the National Survey of Family Growth (NSFG), a large-scale national survey of women ages 15 to 44 years, reveal that family income is associated with adolescents' protection against HIV and many other STDs; adolescents from poor and low-income families are more likely to report an earlier age of sexual experience than their counterparts from higher income families.

In addition to early sexual activity, many adolescents have multiple sex partners within a short period of time in a pattern of serial monogamy which also increases their risk of acquiring STD for two important reasons: it increases the likelihood of being exposed to a sexually transmitted pathogen, and it may reflect poor choices of sexual partners. Among the sexually experienced high school students responding to the YRBSS, 14.4 percent reported having four or more sex partners. Multiple sex partners were noted more frequently among African-American students (41.7% of males and 16.3% of females), compared to Hispanic (20.5% of males and 11.2% of females) and Caucasian (11.5% of males and 10.1% of females) students.

Involuntary sexual intercourse such as rape and sexual abuse may occur more commonly among adolescents, especially younger adolescent women, and often pose a potential risk for acquisition of STDs. A study on the effects of child abuse (i.e., incest, extra-familial sexual abuse, and physical abuse) on adolescent males showed a strong association between abuse and a number of risk-taking behaviors, such as forcing female sexual partners into having sexual intercourse and drinking alcohol prior to sexual intercourse. Moreover, when sexual intercourse is intermittent, as it is with most sexually experienced adolescents, the adolescents are less likely to take proper measures to safeguard against STDs.

CONTRACEPTIVE USE. Sexually experienced adolescents are also at risk for STDs because of their patterns of contraceptive use, especially their use of barrier-method contraceptives. Some data indicate that adolescents do not use effective methods to reduce their risk of STDs or unintended pregnancies. Sexual abstinence is the only sure method of eliminating risk for STDs. When used consistently and correctly, however, condoms offer the best protection against acquisition of STDs, including HIV. Even when condoms are used improperly they reduce the risk of acquiring infections by 50 percent.

The overall reported use of contraceptives, particularly condoms, has increased among adolescents between 1994 and 2004. Data from the 2003 YRBSS reveal that 63.0 percent of the students who reported sexual activity in the three months prior to the survey also reported using condoms during their last sexual encounter; this behavior was more common among males of virtually all ages and racial/ethnic groups. In contrast, 20.6 percent of adolescent women ages 15 to 19 years reported use of birth control pills. It appears that while the use of oral contraceptives provides some protection against the development of gonococcal and nongonococcal forms of PID, it may increase the risk of chlamydial endocervical infections, and provides no protection against most STDs.

Differences in the types and patterns of contraceptive use by race/ethnicity, age, and socioeconomic status have also been noted. Also, adolescent women of higher income are more likely than young women of lower income to use oral contraceptives. These factors are related to access and use of medical services for reproductive health care. Thus, providing all sexually experienced adolescents with reproductive health counseling and education about the importance of consistently and correctly using barrier-method contraceptives such as condoms may play a crucial role in reducing their risk of acquiring and transmitting STDs.

ALCOHOL AND OTHER DRUG USE. Use of alcohol and other drugs is prevalent among adolescents and thus poses a significant threat to their health. About 40 percent of high school youth responding to the YRBSS have used marijuana at least once with 22.4 percent of these students reporting use of this substance within 30 days before the survey. Cocaine was used at least once by 8.7 percent of the students and by 4.1 percent within 30 days of the survey. The substance of choice, however, is alcohol: 74.9 percent of students had at least one drink at some point in time and nearly half (44.9%) consumed alcohol in the 30 days prior to the survey. Among the current alcohol users, 28.3 percent had five or more drinks on at least one occasion, suggesting that a sizeable proportion of the students are periodic heavy drinkers. Grade, age, and gender differences were noted for lifetime and current use of alcohol and other illicit substances. In general, students in higher grade levels (grades 11 and 12) and males were more likely to use all substances. Racial/ethnic differences in use of substances were also found. Heavy use of alcohol was most prevalent among Caucasian and Hispanic males and females, while marijuana use was most common among African-American and Hispanic males.

Although these data strongly suggest that adolescents are at increased risk for social and physical morbidities, and even premature mortality because of their use of alcohol and other illicit substances, they underrepresent the actual prevalence of substance use among all adolescents. Teens who have dropped out or who are repeatedly absent from school and those who are homeless or otherwise disenfranchised are not represented by the reported data; many of these teens are potentially at higher risk for STDs because of their substance use behavior.

Substance use prior to sexual intercourse is likely to be related to a number of risk-taking behaviors: sexual intercourse with a casual acquaintance, lack of communication about use of condoms or previous sexual experiences, and no use of condoms. This association remained significant regardless of demographic factors, sexual experience, and dispositional factors such as adventure and thrill seeking. It appears that early intervention to prevent the use and abuse of alcohol and other substances may significantly decrease their risk of acquiring STDs.

Psychosocial Factors

One study of college students examined the relationship between sexual behavior, substance use, and specific constructs from social cognitive theory (i.e., perceptions of self-efficacy, vulnerability to HIV risk, social norms, negative outcome expectancies of condoms, and knowledge of HIV risk and prevention). The results indicate that although young men expected more negative outcomes of condom use and were more likely to have sexual intercourse under the influence of alcohol and other drugs, young women reported perceptions of higher self-efficacy to practice safer sex. The study further revealed that perceptions of higher self-efficacy to engage in safer sexual behaviors, perceptions of fewer negative outcomes of condom use, and less frequent alcohol and drug use with sexual intercourse were the best predictors of safer sexual behaviors.

Evaluating Std Risk

The information, motivation, and behavioral skills (IMB) model is one method of evaluating risk for STDs. This model posits that information, motivation, and behavior are the primary determinants of AIDS-related preventive behavior. Specifically, the model asserts that information regarding the transmission of HIV and information concerning specific methods of preventing HIV (e.g., condom use, decreasing the number of partners) are necessary prerequisites of reducing risk behaviors.

Motivation to change risk behaviors is another determinant of prevention and affects whether a person acts on his or her knowledge of the transmission and prevention of HIV. The IMB contends that motivation to engage in prevention behaviors is a function of one's attitudes toward the behavior and of subjective norms regarding prevention behaviors. Other critical factors which are hypothesized to influence motivation to engage in prevention behaviors are perceived vulnerability to acquiring HIV, perceived costs and benefits of engaging in prevention behaviors, intention to engage in prevention behaviors regarding HIV, as well as characteristics of the sex partner and/or the sexual relationship (e.g. primary vs. secondary partner).

Behavioral skills for engaging in specific prevention behaviors are a third determinant of prevention; it affects whether a knowledgeable, highly motivated person will be able to change his or her behavior to prevent HIV. Important skills required to engage in prevention behaviors include the ability to effectively communicate with one's sex partner about safer sex, refusal to engage in unsafe sexual practices, proper use of barrier-method contraceptives, and the ability to exit a situation when prevention behaviors are not possible. In addition, individuals who are able to practice prevention skills are presumed to have a strong belief in their ability to practice these prevention behavioral skills. Overall, the IMB asserts that information and motivation trigger behavioral skills to affect the initiation and maintenance of HIV prevention behaviors.

Symptoms of Common Stds

The symptoms of some STDs may seriously affect an infected individual's quality of life or eventually become fatal, while others are so mild as to go undetected. The symptoms of some of the more prevalent STDs include:

• Gonorrhea: The most common symptoms among infected adolescent girls are vaginal discharge, bleeding between menstrual cycles, and painful urination. Among adolescent boys, common symptoms are burning or painful urination and pus-like discharge from the penis. Many infections, however, remain asymptomatic in both females (32%) and males (2%). Symptoms are similar among young children who have contracted gonorrhea from a sexual abuser.
• Chlamydia: Symptoms of chlamydia are similar to those of gonorrhea and sometimes difficult to differentiate clinically. Chlamydial infections are more likely to be asymptomatic than gonorrheal infections and thus are of longer duration on average.
• Syphilis: In primarily syphilis, the characteristic symptom is the appearance of a chancre (painless ulcer) at the site of initial exposure (e.g. external genitalia, lips, tongue, nipples, or fingers). In some cases, the infected individual will experience swollen lymph glands. In secondary syphilis, the infection becomes systemic and the individual experiences symptoms such as fever, headache, sore throat, rash, and swollen glands. During latent syphilis, symptoms go unnoticed. During the late stage of syphilis, the infection has spread to organ systems and may cause blindness, signs of damage to the nervous system and heart, and skin lesions.
• Herpes simplex virus: The symptoms of genital herpes include burning and itching of the genital area, blisters or sores on the genitals, discharge from the vagina or penis, and/or flu-like symptoms such as headache and fever.
• Human papillomavirus (HPV): The warty growths of HPV can appear on the external or internal reproductive organs of males and females but are commonly found on the labia minora and the opening to the vagina in females and the penis in males. They may be small and few or combine to form larger growths.
• Human immunodeficiency virus (HIV): Some persons who are newly infected with HIV have rash, fever, enlarged lymph nodes, and a flu-like illness sometimes called HIV seroconversion syndrome. This initial syndrome passes without intervention, and later symptoms, when T-cells become depleted, include weight loss, chronic cough, fever, fatigue, chronic diarrhea, swollen glands, white spots on the tongue and inside of the mouth, and dark blotches on the skin or in the mouth.

When to Call the Doctor

If a child or adolescent develops any of the symptoms of STDs, he or she should be evaluated for possible infection. Routine pelvic exams are recommended for all sexually active females and all females over the age of 18.

Diagnosis

A history of sexual activity is collected from all individuals at increased risk of contracting an STD, including adolescents who admit to being sexually active or who are pregnant or have undergone therapeutic abortion, adolescents or children with symptoms indicative of infection with an STD, and adolescents or children suspected of being victims of sexual abuse or rape. The healthcare provider will take a complete medical history and perform a thorough physical examination. Depending on the STD in question, additional tests may be performed such as blood work, Papanicolaou (pap) smear, rectal swabs, or biopsy.

Treatment

The treatment of sexually transmitted diseases varies according to the diagnosed infection. Gonorrhea, chlamydia, and syphilis are curable in most cases with antibiotics, although antibiotic-resistant strains do exist. As viruses, HSV, HPV, and HIV are treatable but not curable. The frequency and duration of HSV lesions can be reduced with antiviral therapy, including acyclovir (Zovirax), famciclovir (Famvir), and valacyclovir (Valtrex). Common methods to reduce genital warts include application of a topical cream called imiquimod (Aldara), cryotherapy (freezing of the wart), elecrosurgery (applying an electrical current to the wart), and surgical removal. The course of HIV infection can be slowed with a number of different kinds of drugs, including reverse transcriptase inhibitors, protease inhibitors, nonnucleoside reverse transcriptase inhibitors, and fusion inhibitors.

Alternative Treatment

A number of different alternative therapies may be pursued to treat STDs, such as the use of herbs, homeopathy, acupuncture, and nutritional supplements, although minimal research has been done to establish their efficacy.

Nutritional Concerns

In some cases, supplementation with specific nutrients may enhance immunity and minimize outbreaks. Examples are vitamin C (to boost the immune system), zinc (to reduce the frequency of HSV outbreaks), aloe (a possible antiviral), lemon balm (to speed healing), and licorice (with anti-inflammatory and antiviral effects).

Prognosis

Most STDs have excellent prognoses and respond well to treatment. While HSV and HPS are not curable, outbreaks can be managed and infection generally has little effect on quality of life. HIV, however, is a potentially fatal disease which can be treated but not cured.

Prevention

The prevalence data on STDs, HIV, and AIDS in adolescents indicate that younger women, gay and bisexual teens, and poor, urban and racial/ethnic minority young people have higher rates of STDs and HIV relative to their peers. Primary prevention of initial STD infections through prevention and risk reduction programs are essential for stemming the tide of these sexually acquired diseases. Moreover, secondary prevention through screening at risk adolescents for asymptomatic STD infections and effectively treating the index case and his or her sexual contact(s) are the most effective means of eliminating long-term medical and psychosocial consequences from STDs.

Prevention of high risk sexual, contraceptive, and substance use behaviors through cognitive-behavioral skills training and prevention and risk reduction counseling programs is a key strategy for decreasing the high incidence of STDs in adolescents. Prevention and risk reduction strategies should be developed and implemented in settings in which most adolescents can be reached, including schools or community-based programs in which there are multiple opportunities to intervene with adolescents or clinical settings where one-to-one risk reduction counseling can occur and actual risk can be assessed.

Cognitive-Behavioral Skills Building Interventions

In order to prevent new STD infections, adolescents must not only be informed about the risk and prevention of STDs, they must also have skills to resist peer pressure, negotiate the use of condoms, and project the future consequences of their behaviors. In addition, prevention of STDs in adolescents requires that they have the necessary means, resources, and social support to develop self-regulative skills and self-efficacy to effectively reduce their risk of disease transmission. Such cognitive-behavioral skills building programs have been shown to be effective in developing skills, delaying the onset of sexual activity, and changing high risk behaviors associated with pregnancy, STDs, and HIV infection. Moreover, cognitive-behavioral skills building programs should be immediate, sustained, and cost-effective. Specifically, these programs should be designed to increase knowledge about the prevention and transmission of STDs and their consequences; formulate realistic attitudes and perceptions about personal susceptibility to acquiring infections; enhance self-efficacy and self-motivation; monitor and regulate STD-related risk behaviors; address the role of social peer norms; and develop appropriate decision-making, problem-solving, and communication skills.

Prevention and Risk Reduction Counseling

Counseling strategies to prevent and reduce the risk of STDs should be conducted in a confidential and nonjudgmental manner that is both developmental and culturally appropriate for the adolescent. Counseling should focus on a number of key elements such as maintenance and support of healthy sexual behaviors (e.g. delaying initiation of sexual intercourse, limiting the number of sexual partners), use of barrier-method contraceptives (e.g. condoms, diaphragms, spermicide), routine medical care and advice (e.g. seeking medical care if the adolescent has participated in high-risk behavior), compliance with treatment recommendations (e.g. taking all medications as directed), and encouraging sex partners to seek medical care. Adolescents should also be informed about the myths and misconceptions of acquiring STDs. Moreover, adolescents should receive anticipatory guidance to assist them in defining appropriate options and alternatives to engaging in high-risk behaviors.

Parental Concerns

Parents should be encouraged to talk to their children about sexually transmitted diseases and the risks of sexual activity. By asking preteens or teenagers questions about what they knows about STDs or by using cues from television shows or newspaper articles, parents can help make their children more comfortable talking about sex and the risks of infection, thereby opening the lines of communication. It is important that adolescents be provided accurate information, even if they already have some knowledge on the topic. Research has shown teens are not more likely to have sex if they are informed about safe sex practices, but they are more likely to practice safer sex.

Resources

Books

Hammerschlag, Margaret R., Sarah A. Rawstron, and Kenneth Bromberg. "Sexually Transmitted Diseases." In Krugman's Infectious Diseases of Children, 11th ed. Edited by Anne A. Gershon, Peter J. Hotez, and Samuel L. Katz. New York: Mosby, 2004.

Jenkins, Renee R. "Sexually Transmitted Diseases." In Nelson Textbook of Pediatrics, 17th ed. Edited by Richard E. Behrman, Robert M. Kliegman, and Hal B. Jenson. Philadelphia: Saunders, 2004.

MacDonald, Noni E., and David M. Patrick. "Sexually Transmitted Disease Syndromes." In Principles and Practice of Pediatric Infectious Diseases, 2nd ed. Edited by Sarah S. Long. New York: Churchill Livingstone, 2003.

Periodicals

Department of Health and Human Services, Centers for Disease Control and Prevention. "Youth Risk Behavior Surveillance: United States, 2003." Morbidity and Mortality Weekly Report 53, no. SS-2 (May 21, 2004): 12–20.

Organizations

Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. Web site: www.cdc.gov.

Web Sites

Divisions of HIV/AIDS Prevention, National Center for HIV, STD, and TB Prevention. "HIV/AIDS Surveillance in Adolescents." Centers for Disease Control and Prevention (CDC), August 25, 2004. Available online at www.cdc.gov/hiv/graphics/adolesnt.htm (accessed January 17, 2005).

Divisions of STD Prevention, National Center for HIV, STD, and TB Prevention. "Sexually Transmitted Disease Surveillance 2002 Supplement: Syphilis Surveillance Report." Centers for Disease Control and Prevention (CDC), January 2004. Available online at www.cdc.gov/std/Syphilis2002/SyphSurvSupp2002.pdf (accessed January 17, 2005).

Gearhart, Peter A., et al. "Human Papillomavirus." eMedicine, December 13,, 2004. Available online at www.emedicine.com/med/topic1037.htm (accessed January 17, 2005).

Lamprecht, Catherine. "Talking to Your Child about STDs." Nemours Foundation, May 2001. Available online at (accessed January 17, 2005).

[Article by: Stephanie Dionne Sherk]

Sexually transmitted diseases (STDs) are caused by a group of infectious microorganisms that are transmitted mainly through sexual activity. These agents represent a costly, burdensome global public health problem. STDs can cause harmful, often irreversible, clinical complications, including reproductive health problems, fetal and perinatal health problems, and cancer, and they are also linked in a causal chain of events to the sexual transmission of human immunodeficiency virus (HIV) infection. Although STDs are largely preventable through behavior modification and sound primary health care, they are under-recognized and under-appreciated as a public health problem by most healthcare providers, the general public, and healthcare policy makers. In 1997, the Institute of Medicine characterized STDs as "hidden epidemics of tremendous health and economic consequence" in the United States and advocated urgent national preventive action.

An estimated 333 million curable STDs occur annually worldwide. In the United States, STDs are among the most frequently reported infectious diseases nationwide. Each year an estimated 15 million new cases of STDs occur in Americans, including nearly 4 million infections in U.S. teenagers. The annual direct and indirect costs of the principal STDs, including sexually transmitted HIV infection, and their complications are estimated at $17 billion.

More than twenty-five bacteria, viruses, protozoa, and yeasts are considered sexually transmissible. Bacterial STDs include those caused by Chlamydia trachomatis (chlamydia), Neisseria gonorrhoeae (gonorrhea), Treponema pallidum (syphilis), Haemophilus ducreyi (chancroid), and other common sexually transmitted organisms. Chlamydia and gonorrhea cause inflammatory reactions in the host. In women, these organisms can ascend into the upper reproductive tract where pelvic inflammatory disease (PID) can cause irreparable damage to the reproductive organs and result in infertility, ectopic pregnancy, and chronic pelvic pain. In its early stages, syphilis causes painless genital ulcers and other infectious lesions. Left untreated, syphilis moves through the body in stages, damaging many organs over time. Chancroid is associated with painful genital lesions. In pregnant women, acute bacterial STDs can cause potentially fatal congenital infections or perinatal complications, such as eye and lung infections in the newborn. Effective single-dose antimicrobials can cure chlamydia, gonorrhea, syphilis, and chancroid.

Viral STDs include the sexually transmitted viral infections caused by human immunodeficiency virus (HIV infection), herpes simplex virus type 2 (genital herpes), and human papillomavirus (HPV infection). Initial infections with these organisms may be asymptomatic or cause only mild symptoms. Treatable but not curable, viral STDs appear to be lifelong infections. HIV is the virus that causes acquired immunodeficiency syndrome (AIDS). Herpes causes periodic outbreaks of painful genital lesions. Some strains of HPV cause genital warts, and others are important risk factors for cervical dysplasia and invasive cervical cancer. Hepatitis B virus (HBV) is another acute viral illness that can be transmitted through sexual activity. Most persons who acquire HBV infection recover and have no complications, but it can sometimes become a chronic health problem.

Trichomonas vaginalis (trichomoniasis) is a common protozoal STD, and Candida species (candidiasis) are sexually transmitted yeasts. Both are frequently associated with vaginal discharge.

Biological Factors in the Spread of Stds

STDs are behavior-linked diseases that result from unprotected sex. Nonetheless, several biological factors contribute to their spread. These include the asymptomatic nature of STDs, the long lag time between infections and complications, the higher susceptibility of women to STDs, and the way that STDs facilitate the transmission of HIV infection.

The silent nature of STDs represents their greatest public health threat. Most STDs cause some symptomatic illness, but many produce symptoms so mild or nonspecific that infected persons are not alerted to seek medical care. As many as one in three men and two in three women with chlamydia infection have no obvious signs of infection. Without treatment or other interventions, infected persons can continue to infect new sex partners. Moreover, serious complications that cause irreversible damage can occur "silently" before any symptoms are apparent. A related problem is the long interval that can elapse between acquiring an STD and recognizing a clinically significant health problem. Women can develop cervical cancer many years after infection with some strains of HPV. A woman may first suspect she had an asymptomatic infection with chlamydia or gonorrhea when she finds out later in life that she is infertile or has an ectopic pregnancy. Because the original infection was likely to have been asymptomatic, there is frequently no perceived connection between the original sexually acquired infection and the resulting health problem. The lack of awareness of this connection leads people to underestimate their risk and to forego preventive precautions.

Gender and age are also associated with increased risk for STDs. Women are at higher risk than men for most STDs, and young women are more susceptible to certain infections than older women. Due to cervical ectopy that is extremely common in adolescent females, the immature cervix of adolescent females is covered with cells that are especially susceptible to STDs such as chlamydia.

The presence of other STDs, especially those that cause genital ulcers or inflammation, influences the sexual transmission and acquisition of HIV infection. Studies have repeatedly demonstrated that people are two to five times more likely to become infected with HIV through sexual contact when other STDs are present. In addition, dually infected persons (persons who are infected with both HIV and another STD) are more likely to transmit HIV infection during sexual contact. Conversely, effective STD detection and treatment can slow the spread of HIV infection at the individual and community levels. For example, in a study in Malawi in the mid-1990s, treatment of gonorrhea in HIV-infected men returned the frequency and concentration of HIV genetic material in semen to levels comparable to levels found in HIV-infected men who were not infected with other STDs. Similarly, a community trial in Tanzania in the mid-1990s demonstrated that treatment of symptomatic STDs resulted in a 42-percent decrease in new heterosexually transmitted HIV infections.

Social Factors That Affect the Spread of Stds

Some social factors directly affect STD spread especially in vulnerable populations. In addition, the stigma that continues to surround STDs in the United States indirectly interferes with establishing new social norms pertaining to sex and sexuality.

When there are barriers to health care, it is difficult to detect and treat STDs early. Infected persons also miss an opportunity for behavioral change counseling. Health care access barriers keep infected persons in the community where they continue to spread STDs. In the United States, groups with the highest rates of STDs are the same groups in which access to health care services is limited or absent.

Perhaps the greatest social factor contributing to the spread of STDs, and the factor that most significantly separates the United States from industrialized countries with low STD rates, is the stigma that continues to be associated with sexually transmitted infections. Although sex and sexuality pervade many aspects of American culture, most Americans are secretive and private about their sexual behavior. Talking openly and comfortably about sex and sexuality is difficult even in intimate relationships. This secrecy about sexuality and STDs adversely affects STD prevention in the United States by thwarting sexuality and STD education programs for adolescents, hindering communication between parents and children and between sex partners, promoting unbalanced sexual messages in the media, obstructing education and counseling activities, and impeding research on sexual behaviors.

Groups Disproportionately Affected By Stds

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

STDs disproportionately affect disenfranchised persons and individuals who are in social networks characterized by high-risk sexual behaviors, substance abuse, and limited access to health care. Some notable disproportionately affected groups include sex workers, homeless persons and runaways, adolescents and adults in detention, and migrant workers. Many studies document the association of substance use, especially alcohol and drug use, with STDs. The introduction of illicit substances into communities can dramatically alter sexual behavior in high-risk sexual networks leading to epidemic spread of STDs. The national U.S. syphilis epidemic of the late 1980s was fueled by the effect of increased crack cocaine use, especially in minority communities. Crack cocaine led to increases in sex exchanged for drugs and in the number of anonymous sex partners and decreased health care-seeking behavior and motivation to use barrier protection—all factors that can increase STD transmission in a community. Other substances, including alcohol, can also affect a person's cognitive and negotiating skills before and during sex, lowering the likelihood that preventive action will be taken to protect against STDs and pregnancy.

Gender disparities are an important aspect of the epidemiology of STDs. Compared to men, women suffer more frequent and serious STD complications, including PID, ectopic pregnancy, infertility, and chronic pelvic pain. Women are biologically more susceptible to infection when exposed to a sexually transmitted agent, and STDs are often more easily transmitted from a man to a woman than from a woman to a man. Given that some newly acquired STDs (and even some long-term complications) are only mildly symptomatic or completely asymptomatic in women, the combination of increased susceptibility and silent infection frequently results in delayed STD diagnosis and treatment. A further complication is that STDs are more difficult to diagnose in women due to the complex anatomy of the female reproductive tract and the frequent need for a speculum examination and diagnostic culture tests.

In pregnant women, STDs can result in serious health problems or death to a developing fetus or newborn. Sexually transmitted pathogens can be transmitted across the placenta, resulting in congenital infection, or can reach the newborn during vaginal childbirth, resulting in perinatal infection. Regardless of the route of infection, these organisms can permanently damage the fetal or newborn brain, spinal cord, eyes, auditory nerves, or immune system. Even when the organisms do not reach the fetus or newborn directly, they can cause spontaneous abortion, stillbirth, premature rupture of the membranes, and preterm delivery.

For a variety of behavioral, social, and biological reasons, STDs also disproportionately affect adolescents. In 1998, U.S. teenagers 15 to 19 years old had the highest reported rate of chlamydia and the second highest rate of gonorrhea. The herpes infection rate among white youth in the United States aged twelve to nineteen increased nearly fivefold from the late 1970s to the early 1990s. Because not all teenagers are sexually active, the actual rate of STDs among teens is even higher than the observed rates suggest. There are several contributing factors. Many teenagers are, in fact, sexually active and at risk for STDs, and they are having sex with partners from sexual networks that are already highly infected with untreated STDs. In 1999, among U.S. high school youth interviewed for the Youth Risk Behavior Surveillance System survey, half (49.9%) indicated they had had sexual intercourse during their lifetimes. Early sexual activity and multiple sexual partners were commonly reported among American high school youth; 8.3 percent of students indicated they had first had sex before age thirteen, and 16.2 percent said they had four or more sex partners during their lifetime. Despite the supposedly easy access to condoms that can lower STD transmission risk considerably, only 58 percent of sexually active students said they used a condom the last time they had intercourse. Sexually active teenagers are often reluctant to seek STD services or face serious obstacles to obtaining such services. In addition, health care providers are often uncomfortable discussing sexuality and risk reduction with young persons.

Some minority racial and ethnic groups (mainly black and Hispanic populations) in the United States have higher rates of STDs compared with rates for whites. Race and ethnicity in the United States are risk markers that correlate with other more fundamental determinants of health status such as poverty, access to quality health care, health care-seeking behavior, illicit drug use, and living in communities with high STD prevalence. Public health data may over-represent STDs among racial and ethnic groups who are more likely to receive STD services from public sector STD clinics characterized by timely and complete reporting of public health statistics. However, even when random sampling techniques are used to study health problems, higher rates of STDs are often found among African Americans and Hispanics compared with whites.

Factors Important to the Prevention and Control of Stds

The dynamics of how STDs spread in populations have been studied extensively to derive approaches to prevention and control. Three main factors predict how fast and at what level STDs will spread in a population: the nature of sexual relationships, the degree to which susceptibility to STDs can be modified, and the timeliness and completeness of treatment.

The nature of sexual relationships refers to the decisions people make about when to become and remain sexually active and whom to select as sex partners. The earlier that vaginal, oral, or anal sexual intercourse begins and the greater the number of lifetime sex partners, the more likely a person is to acquire one or more STDs in a lifetime. Behavioral interventions that help delay the initiation of intercourse and reduce the lifetime number of sex partners will have a positive effect on slowing STD transmission.

Susceptibility to STDs can be modified with vaccines or barrier contraceptives such as condoms. If uninfected persons are somehow immune to STDs, then no transmission will occur. The availability of effective vaccines against STDs could dramatically slow increases in or even eliminate some STDs. For example, there is an effective and widely available vaccine for hepatitis B, a viral STD. Current strategies to immunize all children against hepatitis B before they become sexually active could greatly reduce the societal burden of this disease. Susceptibility can also be altered each time sex occurs. The correct and consistent use of condoms can reduce the rate of STD transmission in a population. Persons who choose to engage in sexual behaviors that place them at risk of STDs should use latex or polyurethane condoms every time they have sex. A condom put on the penis before starting sex and worn until the penis is withdrawn can help protect both the male and the female partner from most STDs. When a male condom cannot be used appropriately, sex partners should consider using a female condom. However, condoms do not provide complete protection from all STDs. Sores and lesions of STDs on infected men and women may be present in areas not covered by the condom, resulting in transmission of infection to a new person. This is common with genital warts and other genital HPV infections.

Although condom use has been on the rise in the United States over the past few decades, women who use the most effective forms of contraception (sterilization and hormonal contraception) are less likely than other women to use condoms for STD prevention. The most effective methods of contraception are not the most effective methods of STD prevention; likewise, methods that give a considerable measure of protection against STDs are considered to be good, but not the most effective, methods of pregnancy prevention. This suggests that, especially for young women who are at highest risk for unwanted pregnancy and STDs, using dual protection (condoms and hormonal contraception) will offer the best overall protection against both.

The third factor in STD prevention and control focuses on finding and treating infected persons and their sex partners. The longer someone has an untreated STD (especially if the person is asymptomatic), the longer that person can potentially infect others. If that interval can be shortened for the millions of persons who acquire STDs each year, then transmission would slow appreciably. Screening and treatment are the biomedical approaches that can be applied to this situation. For STDs that are frequently asymptomatic, screening and treatment also benefit those likely to suffer severe complications (especially women) if infections are not detected and treated early. For example, in the early 1990s, chlamydia screening in a large metropolitan managed-care organization reduced the incidence of subsequent PID in the screened group by 40 percent. Identifying and treating partners of persons with curable STDs has always been an integral part of organized control programs. Theoretically, this can break the chain of transmission in a sexual network. Early antibiotic treatment of a sex partner can interfere with an STD taking hold in a recently exposed person. Partner treatment benefits the original patient by reducing the risk of reinfection, and the partner benefits by avoiding acute infection and potential complications. Because future sex partners are protected by treating partners, this strategy also benefits the community. New screening tests (some of which can be performed on urine specimens) that facilitate STD screening in nontraditional settings are now available.

Many examples demonstrate the effectiveness of organized approaches to STD prevention and control that incorporate these strategies on a large scale. When a sustained, collaborative, multifaceted approach to STD prevention and control is undertaken, dramatic results can be achieved. One need only observe the results of sustained STD prevention efforts in many countries in Western and Northern Europe, Canada, Japan, and Australia, where STD rates are many times lower than in the United States, to conclude that STD prevention programs can work on a national scale.

Bibliography

American Social Health Association (1998). Sexually Transmitted Diseases in America: How Many Cases and at What Cost? Menlo Park, CA: Kaiser Family Foundation.

Anderson, J.; Brackhill, R.; and Mosher, W. (1996). "Condom Use for Disease Prevention among Unmarried U.S. Women." Family Planning Perspectives 28:25–28, 39.

Anderson, R. M., and May, R. M. (1991). Infectious Diseases of Humans: Dynamics and Control. Oxford: Oxford University Press.

Centers for Disease Control and Prevention (1998). "1998 Guidelines for Treatment of Sexually Transmitted Diseases." Morbidity and Mortality Weekly Report 47(RR-1):1–116.

—— (1999). Sexually Transmitted Disease Surveillance, 1998. Atlanta, GA: Centers for Disease Control and Prevention, 1–115.

—— (2000). "Youth Risk Behavior Surveillance: United States, 1999." Morbidity and Mortality Weekly Report 49(SS-5).

Cohen, M. S.; Hoffman, I. F.; Royce, R. A. et al. (1997). "Reduction of Concentration of HIV-1 in Semen after Treatment of Urethritis: Implications for Prevention of Sexual Transmission of HIV-1." Lancet 349:1868–1873.

Fleming, D. T.; McQuillan, G. M.; Johnson, R. E. et al. (1997). "Herpes Simplex Virus Type 2 in the United States: 1976–1994." New England Journal of Medicine 337:1105–1111.

Goldenberg, R. L.; Andrews, W. W.; Yuan, A. C. et al. (1997). "Sexually Transmitted Diseases and Adverse Outcomes of Pregnancy." Clinics in Perinatology 24(1):23–41.

Grosskurth, H.; Mosha, F.; Todd, J. et al. (1995). "Impact of Improved Treatment of Sexually Transmitted Diseases on HIV Infection in Rural Tanzania: Randomised Controlled Trial." Lancet 346:530–536.

Gunn, R.; Montes, J.; Tomey, K. et al. (1995). "Syphilis in San Diego County, 1983–1992: Crack Cocaine, Prostitution, and the Limitations of Partner Notification." Sexually Transmitted Diseases 22:60–66.

Hillis, S.; Nakashima, A.; Amsterdam, L. et al. (1995). "The Impact of a Comprehensive Chlamydia Prevention Program in Wisconsin." Family Planning Perspectives 27:108–111.

Holmes, K.; Mardh, P.; Sparling, P. et al., eds. (1999). Sexually Transmitted Diseases, 3rd edition. New York: McGraw-Hill.

Institute of Medicine. Committee on Prevention and Control of Sexually Transmitted Diseases (1997). The Hidden Epidemic: Confronting Sexually Transmitted Diseases, eds. T. R. Eng and W. T. Butler. Washington, DC: National Academy Press.

Scholes, D.; Stergachis, A.; Heidrich, F. et al. (1996). "Prevention of Pelvic Inflammatory Disease by Screening for Cervical Chlamydial Infection." New England Journal of Medicine 334:1362–1366.

St. Louis, M. E.; Wasserheit, J. N.; and Gayle, H. D. (1997). "Editorial: Janus Considers the HIV Pandemic: Harnessing Recent Advances to Enhance AIDS Prevention." American Journal of Public Health 87:10–12.

Tsui, A.; Wasserheit, J.; and Haaga, J. (1997). Reproductive Health in Developing Countries: Expanding Dimensions, Building Solutions. Washington, DC: National Academy Press.

— ALLISON L. GREENSPAN; JOEL R. GREENSPAN

Venereal diseases, or as the military currently defines them, sexually transmitted diseases (STDs), occur most often in sexually active people less than twenty‐four years of age. Because military forces historically have consisted of mostly young people, predominantly young men, often sexually active, the incidence of STD in military personnel has always been two to three times that of a similar matched group of civilians. This rate can rise five to eight times higher during wartime.

Some form of STDs seems to have plagued military forces from earliest recorded history. Herodotus in the fifth century B.C.E. wrote that Scythian soldiers who pillaged the Celestial Temple of Venus were infected with a “female disease” that afflicted all of their descendants. The first recorded cases of syphilis appeared in Europe in 1493 supposedly among Spanish sailors returning from the New World. Spanish and French armies soon spread what was called the “Neapolitan disease” or the “French pox” throughout Europe.

Historically, two methods have been advocated for controlling rates of STDs in the U.S. military: punishment of soldiers and support for regulation of civilian conveyors of the disease through regular examination and treatment of prostitutes. Traditionally when rates became high, particularly in wartime, regulation was enforced; when rates returned to baseline levels, the military either ignored the problem or relied upon punitive action. Such shifts in policy occurred during the Civil War, the Spanish‐American War, and World War I. The primary reason was that the methods of treatment, which consisted chiefly of local applications of antiseptics (containing arsenic, mercury, and bismuth), were only marginally effective. In addition, infected soldiers often did not develop a persistent and immediately debilitating illness, although they often became asymptomatic and infectious carriers. During World War I, the military public health authorities sought to eliminate prostitution in the areas around U.S. military and naval bases.

During World War II, the public health authorities encouraged publicity about venereal disease, breaking a long taboo on public discussion. The advent of antibiotics, especially penicillin, had a dramatic impact on STDs, primarily gonorrhea and syphilis. Another effective preventive measure was the use of condoms, which were distributed to all members of the armed forces.

STDs reemerged as a major problem in the military in the 1960s and 1970s as a result of several new developments. In the wider society, the “sexual revolution” in attitudes and behavior meant that sexual encounters were more readily accepted as a social norm. There was also indiscriminate use of antibiotics, thus reducing their effectiveness. And in 1976, new resistant strains of gonorrhea emerged first in the Far East, then in the United States which within a decade rendered many antibiotic treatments useless. Further, new sexually‐transmitted viral agents emerged: herpes; venereal warts (Papilloma virus); hepatitis B; and the deadly AIDS virus, HIV.

STDs have always been a problem for the military. Attempts to control them by changing behavior have had a significant, if temporary, impact. But recent resistant microorganisms and new STDs threaten to bring back the high prevalence rate that existed before antibiotics.

[See also Casualties; Demography and War.]

Bibliography

• U.S. Army, Medical Department, Preventive Medicine in World War II, Vol. V: Communicable Diseases, ed. John B. Coates, Ebbe C. Haff, and Phebe M. Hoff, 1960.
• Stanhope Bayne‐Jones, The Evolution of Preventive Medicine in the United States Army, 1606–1939, 1968.
• Edmund C. Tramont, AIDS and Its Impact on Medical Readiness, Military Review, 6 (1990), pp. 48–58

Sexually transmitted diseases (STDs) are infections communicated between persons through sexual intercourse or other intimate sexual contact. In the early 1970s, as the number of recognized STDs grew, the World Health Organization adopted the term to supersede the five diseases that collectively had been called venereal diseases (VD), chancroid, gonorrhea, granuloma inguinal, lymphogranuloma venereum, and syphilis. More than sixty other infections of bacteria, protozoa, fungi, and viruses that can be transmitted sexually have been added to the designation.

Of the venereal diseases, gonorrhea and syphilis were the most prevalent in the United States before World War II. Because of the social stigma attached to the diseases and the difficulty in diagnosing them, statistics of their incidence are often unreliable when available at all. One 1901 study concluded that as many as eighty of every one hundred men in New York City suffered an infection of gonorrhea at some time. The same study reported 5 to 18 percent of all men had syphilitic infections. Progressive Era reformers and social critics pointed to the high incidence of venereal diseases and the moral and public health threats they posed to families and communities as evidence of a cultural crisis. Combating venereal diseases was an important component of the social hygiene movement during this period. The high rates of venereal diseases among military personnel also led the U.S. War Department to institute far-reaching anti-VD campaigns during World Wars I and II. Soldiers were told that VD, like the enemy on the battlefield, threatened not only their health but America's military strength.

The reform impulse that began during the Progressive Era and World War I subsided until the 1930s, when the U.S. Public Health Service renewed efforts against syphilis and gonorrhea, resulting in the 1938 passage of the National Venereal Disease Control Act. Disease control efforts in the 1930s included requiring mandatory premarital tests for VD in many states. Widespread disease testing and the introduction of penicillin in 1943 contributed to declining VD rates after World War II. But by the late 1950s the rates began a steady increase that persisted with liberal sexual attitudes in the 1960s and 1970s.

During the 1980s the global pandemic of Acquired Immune Deficiency Syndrome (AIDS) overshadowed other STDs. Between 1981 and 2000, 774,467 cases of AIDS were reported in the United States; 448,060 people died of AIDS. Nearly 1 million other Americans were also infected by the human immunodeficiency virus (HIV), the virus that causes AIDS. The development of powerful antiretroviral therapies during the 1990s prolonged the lives of many Americans infected by HIV or suffering from AIDS.

In 2000, 65 million people in the United States were living with an incurable STD, and annually approximately 15 million new cases of STDs were diagnosed, of which nearly half were incurable. Of particular concern to public health officials was that nearly one-fourth of new STD infections occurred in teenagers. Also of concern was that STDs affected women and African Americans in disproportionately greater numbers and with more complications. The rates of gonorrhea and syphilis, for instance, were thirty times higher for African Americans than for whites. The most common STDs were bacterial vaginosis, chlamydia, gonorrhea, hepatitis B, herpes, human papillomavirus (hpv), syphilis, and trichomoniasis.

Incidence and prevalence vary dramatically from disease to disease. The incidence of some diseases, such as syphilis, reached a historic low in the late 1990s, while those of other diseases, such as chlamydia, genital herpes, and gonorrhea, continued to increase during the same period. STDs also pose an economic cost. The costs of the major STDs and their complications totaled almost $17 billion in 1994. With the emergence of antibiotic-resistant strains of once-treatable STDs, the problem has persisted as a major public health concern.

Bibliography

Brandt, Allan M. No Magic Bullet: A Social History of Venereal Disease in the United States since 1880. New York: Oxford University Press, 1985.

National Center for HIV, STD, and TB Prevention, Division of Sexually Transmitted Diseases. Tracking the Hidden Epidemics, 2000: Trends in STDs in the United States. Atlanta: Centers for Disease Control and Prevention, 2001.

Poirier, Suzanne. Chicago's War on Syphilis, 1937–40: The Times, The Trib, and the Clap Doctor. Urbana: University of Illinois Press, 1995.

Shilts, Randy. And the Band Played On: Politics, People, and the AIDS Epidemic. New York: St. Martin's Press, 1987.

Smith, Raymond A., ed. Encyclopedia of AIDS: A Social, Political, Cultural, and Scientific Record of the HIV Epidemic. New York: Penguin, 2001.

Diseases that can be passed to other persons through sexual contact. AIDS, gonorrhea, herpes, and syphilis are examples of sexually transmitted diseases.

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (March 2009)

Sexually Transmitted Infections
Classification and external resources
Spanish Civil War poster, produced by the Republican government, saying "Avoid venereal diseases ... As dangerous as enemy bullets"
ICD-10	A64.
ICD-9	099.9
DiseasesDB	27130
MeSH	D012749

A sexually transmitted disease (STD), also known as sexually transmitted infection (STI) or venereal disease (VD), is an illness that has a significant probability of transmission between humans or animals by means of sexual contact, including vaginal intercourse, oral sex, and anal sex. While in the past, these illnesses have mostly been referred to as STDs or VD, in recent years the term sexually transmitted infection (STI) has been preferred, as it has a broader range of meaning; a person may be infected, and may potentially infect others, without showing signs of disease. Some STIs can also be transmitted via use of an IV drug needle after its use by an infected person, as well as through childbirth or breastfeeding. Sexually transmitted infections have been well known for hundreds of years.

Contents 1 Classification and terminology 1.1 Bacterial 1.2 Fungal 1.3 Viral 1.4 Parasites 1.5 Protozoal 1.6 Sexually transmitted enteric infections 1.7 Sexually transmissible oral infections 2 Pathophysiology 3 Prevention 3.1 Vaccines 3.2 Condoms 3.3 Nonoxynol-9 4 Diagnosis 5 Treatment 6 Epidemiology 7 History 8 See also 9 References 10 External links

Classification and terminology

Until the 1990s, STDs were commonly known as venereal diseases : Veneris is the Latin genitive form of the name Venus, the Roman goddess of love. Social disease was another euphemism.

Public health officials originally introduced the term sexually transmitted infection, which clinicians are increasingly using alongside the term sexually transmitted disease in order to distinguish it from the former. According to the Ethiopian Aids Resource Center FAQ, "Sometimes the terms STI and STD are used interchangeably. This can be confusing and not always accurate, so it helps first to understand the difference between infection and disease. Infection simply means that a germ — virus, bacteria, or parasite — that can cause disease or sickness is present inside a person’s body. An infected person does not necessarily have any symptoms or signs that the virus or bacteria is actually hurting his or her body; they do not necessarily feel sick. A disease means that the infection is actually causing the infected person to feel sick, or to notice something is wrong. For this reason, the term STI — which refers to infection with any germ that can cause an STD, even if the infected person has no symptoms — is a much broader term than STD."^[1] The distinction being made, however, is closer to that between a colonization and an infection, rather than between an infection and a disease.

Specifically, the term STD refers only to infections that are causing symptoms. Because most of the time people do not know that they are infected with an STD until they start showing symptoms of disease, most people use the term STD, even though the term STI is also appropriate in many cases.

Moreover, the term sexually transmissible disease is sometimes used since it is less restrictive in consideration of other factors or means of transmission. For instance, meningitis is transmissible by means of sexual contact but is not labeled as an STI because sexual contact is not the primary vector for the pathogens that cause meningitis. This discrepancy is addressed by the probability of infection by means other than sexual contact. In general, an STI is an infection that has a negligible probability of transmission by means other than sexual contact, but has a realistic means of transmission by sexual contact (more sophisticated means — blood transfusion, sharing of hypodermic needles —are not taken into account). Thus, one may presume that, if a person is infected with an STI, e.g., chlamydia, gonorrhea, genital herpes, it was transmitted to him/her by means of sexual contact.

Most of the diseases on this list are most commonly transmitted sexually. Some are commonly transmitted in other ways as well; for example, HIV/AIDS is also commonly transmitted through the sharing of infected needles by drug users, while SARS, which can be spread through casual contact such as coughing and sneezing, is very often not associated with sexual activity.

Bacterial

• Bacterial Vaginosis (BV) - not officially an STD but affected by sexual activity.
• Chancroid (Haemophilus ducreyi)
• Donovanosis (Granuloma inguinale or Calymmatobacterium granulomatis)
• Gonorrhea (Neisseria gonorrhoeae)
• Lymphogranuloma venereum (LGV) (Chlamydia trachomatis serotypes L₁, L₂, L₃. See Chlamydia)
• Non-gonococcal urethritis (NGU) (Ureaplasma urealyticum or Mycoplasma hominis)
• Staphylococcal infection (Staphylococcus aureus, MRSA) - Sexually transmissible.^[2]
• Syphilis (Treponema pallidum)

Fungal

• Tinea cruris "Jock Itch" (Trichophyton rubrum and others). - Sexually transmissible.
• Yeast Infection

Viral

• Adenoviruses^[3] thought to contribute to obesity[1] - venereal fluids (also fecal & respiratory fluids)
• Viral hepatitis (Hepatitis B virus) - saliva, venereal fluids.
  (Note: Hepatitis A and Hepatitis E are transmitted via the fecal-oral route; Hepatitis C (liver cancer) is rarely sexually transmittable,^[4] and the route of transmission of Hepatitis D (only if infected with B) is uncertain, but may include sexual transmission.^{[5] [6] [7]})
• Herpes Simplex (Herpes simplex virus (1, 2)) skin and mucosal, transmissible with or without visible blisters
  • Herpes simplex virus 1 may be linked to Alzheimer's disease.^[8]
• HIV/ AIDS (Human Immunodeficiency Virus) - venereal fluids
• HTLV 1, 2 - venereal fluids
• Genital warts - ("low risk" types of Human papillomavirus HPV) - skin and muscosal, transmissible with or without visible warts
• Cervical cancer, anal cancer - ("high risk" types of Human papillomavirus HPV) - skin and muscosal
• Molluscum contagiosum (molluscum contagiosum virus MCV) - close contact
• Mononucleosis
  • (Cytomegalovirus CMV - Herpes 5) - saliva, sweat, urine, feces and venereal fluids.
  • (Epstein-Barr virus EBV - Herpes 4) - saliva
• Kaposi's sarcoma (Kaposi's sarcoma-associated herpesvirus KSHV - Herpes 8) - saliva

Parasites

• Crab louse, colloquially known as "crabs" (Phthirius pubis)
• Scabies (Sarcoptes scabiei)

Protozoal

• Trichomoniasis (Trichomonas vaginalis)

Sexually transmitted enteric infections

Various bacterial (Shigella, Campylobacter, or Salmonella), viral (Hepatitis A, Adenoviruses), or parasitic (Giardia or amoeba) pathogens are transmitted by sexual practices that promote anal-oral contamination (fecal-oral). Sharing sex toys without washing or multiple partnered barebacking can promote anal-anal contamination. Although the bacterial pathogens may coexist with or cause proctitis, they usually produce symptoms (diarrhea, fever, bloating, nausea, and abdominal pain) suggesting disease more proximal in the GI tract.

Sexually transmissible oral infections

Common colds, influenza, Staphylococcus aureus, E. coli, Adenoviruses, Human Papillomavirus, Oral Herpes (1, 2 & 4, 5, 8), Hepatitis B and the yeast Candida albicans can all be transmitted through the oral route.

Pathophysiology

Many STDs are (more easily) transmitted through the mucous membranes of the penis, vulva, rectum, urinary tract and (less often - depending on type of infection)^{[citation needed]} the mouth, throat, respiratory tract and eyes. The visible membrane covering the head of the penis is a mucous membrane, though it produces no mucus (similar to the lips of the mouth). Mucous membranes differ from skin in that they allow certain pathogens into the body.^[9] Pathogens are also able to pass through breaks or abrasions of the skin, even minute ones. The shaft of the penis is particularly susceptible due to the friction caused during penetrative sex. The primary sources of infection in ascending order are venereal fluids, saliva, mucosal or skin (particularly the penis), infections may also be transmitted from feces, urine and sweat.^[10] The amount required to cause infection varies with each pathogen but is always less than you can see with the naked eye.

This is one reason that the probability of transmitting many infections is far higher from sex than by more casual means of transmission, such as non-sexual contact—touching, hugging, shaking hands—but it is not the only reason. Although mucous membranes exist in the mouth as in the genitals, many STIs seem to be easier to transmit through oral sex than through deep kissing. According to a safe sex chart, many infections that are easily transmitted from the mouth to the genitals or from the genitals to the mouth, are much harder to transmit from one mouth to another.^[11] With HIV, genital fluids happen to contain much more of the pathogen than saliva. Some infections labeled as STIs can be transmitted by direct skin contact. Herpes simplex and HPV are both examples. KSHV, on the other hand, may be transmitted by deep-kissing but also when saliva is used as a sexual lubricant.

Depending on the STD, a person may still be able to spread the infection if no signs of disease are present. For example, a person is much more likely to spread herpes infection when blisters are present (STD) than when they are absent (STI). However, a person can spread HIV infection (STI) at any time, even if he/she has not developed symptoms of AIDS (STD).

All sexual behaviors that involve contact with the bodily fluids of another person should be considered to contain some risk of transmission of sexually transmitted diseases. Most attention has focused on controlling HIV, which causes AIDS, but each STD presents a different situation.

As may be noted from the name, sexually transmitted diseases are transmitted from one person to another by certain sexual activities rather than being actually caused by those sexual activities. Bacteria, fungi, protozoa or viruses are still the causative agents. It is not possible to catch any sexually transmitted disease from a sexual activity with a person who is not carrying a disease; conversely, a person who has an STD got it from contact (sexual or otherwise) with someone who had it, or his/her bodily fluids. Some STDs such as HIV can be transmitted from mother to child either during pregnancy or breastfeeding.

Although the likelihood of transmitting various diseases by various sexual activities varies a great deal, in general, all sexual activities between two (or more) people should be considered as being a two-way route for the transmission of STDs, i.e., "giving" or "receiving" are both risky although receiving carries a higher risk.

Healthcare professionals suggest safer sex, such as the use of condoms, as the most reliable way of decreasing the risk of contracting sexually transmitted diseases during sexual activity, but safer sex should by no means be considered an absolute safeguard. The transfer of and exposure to bodily fluids, such as blood transfusions and other blood products, sharing injection needles, needle-stick injuries (when medical staff are inadvertently jabbed or pricked with needles during medical procedures), sharing tattoo needles, and childbirth are other avenues of transmission. These different means put certain groups, such as medical workers, and haemophiliacs and drug users, particularly at risk.

Recent epidemiological studies have investigated the networks that are defined by sexual relationships between individuals, and discovered that the properties of sexual networks are crucial to the spread of sexually transmitted diseases. In particular, assortative mixing between people with large numbers of sexual partners seems to be an important factor.

It is possible to be an asymptomatic carrier of sexually transmitted diseases. In particular, sexually transmitted diseases in women often cause the serious condition of pelvic inflammatory disease.

Prevention

Main article: Safe sex

Prevention is key in addressing incurable STIs, such as HIV & herpes.

The most effective way to prevent sexual transmission of STIs is to avoid contact of body parts or fluids which can lead to transfer with an infected partner. No contact minimizes risk. Not all sexual activities involve contact: cybersex, phonesex or masturbation from a distance are methods of avoiding contact. Proper use of condoms reduces contact and risk.

Ideally, both partners should get tested for STIs before initiating sexual contact, or before resuming contact if a partner engaged in contact with someone else. Many infections are not detectable immediately after exposure, so enough time must be allowed between possible exposures and testing for the tests to be accurate. Certain STIs, particularly certain persistent viruses like HPV, may be impossible to detect with current medical procedures.

Many diseases that establish permanent infections can so occupy the immune system that other diseases become more easily transmitted. The innate immune system led by defensins against HIV can prevent transmission of HIV when viral counts are very low, but if busy with other viruses or overwhelmed, HIV can establish itself. Certain viral STI's also greatly increase the risk of death for HIV infected patients.

Vaccines

Vaccines are available that protect against some viral STIs, such as Hepatitis B and some types of HPV. Vaccination before initiation of sexual contact is advised to assure maximal protection.

Condoms

Condoms only provide protection when used properly as a barrier, and only to and from the area that it covers. Uncovered areas are still susceptible to many STDs. In the case of HIV, sexual transmission routes almost always involve the penis, as HIV cannot spread through unbroken skin, thus properly shielding the insertive penis with a properly worn condom from the vagina and anus effectively stops HIV transmission. An infected fluid to broken skin borne direct transmission of HIV would not be considered "sexually transmitted", but can still theoretically occur during sexual contact, this can be avoided simply by not engaging in sexual contact when having open bleeding wounds. Other STDs, even viral infections, can be prevented with the use of latex condoms as a barrier. Some microorganisms and viruses are small enough to pass through the pores in natural skin condoms, but are still too large to pass through latex condoms.

Condoms are designed, tested, and manufactured to never fail if used properly. There has not been one documented case of an HIV transmission due to an improperly manufactured condom

Proper usage entails:

• Not putting the condom on too tight at the end, and leaving 1.5 cm (3/4 inch) room at the tip for ejaculation. Putting the condom on snug can and often does lead to failure.
• Wearing a condom too loose can defeat the barrier.
• Avoiding inverting, spilling a condom once worn, whether it has ejaculate in it or not, even for a second.
• Avoiding condoms made of substances other than latex or polyurethane, as they don't protect against HIV.
• Avoiding the use of oil based lubricants (or anything with oil in it) with latex condoms, as oil can eat holes into them.
• Using flavored condoms for oral sex only, as the sugar in the flavoring can lead to yeast infections if used to penetrate.

Not following the first five guidelines above perpetuates the common misconception that condoms aren't tested or designed properly.

In order to best protect oneself and the partner from STIs, the old condom and its contents should be assumed to be still infectious. Therefore the old condom must be properly disposed of. A new condom should be used for each act of intercourse, as multiple usage increases the chance of breakage, defeating the primary purpose as a barrier.

Nonoxynol-9

Nonoxynol-9 a vaginal microbicide was hoped to decrease STD rates. Trials however have found it ineffective.^[12]

Diagnosis

STI tests may test for a single infection, or consist of a number of individual tests for any of a wide range of STIs, including tests for syphilis, trichomonas, gonorrhea, chlamydia, herpes, hepatitis and HIV tests. No procedure tests for all infectious agents.

STI tests may be used for a number of reasons:

• as a diagnostic test to determine the cause of symptoms or illness
• as a screening test to detect asymptomatic or presymptomatic infections
• as a check that prospective sexual partners are free of disease before they engage in sex without safer sex precautions (for example, in fluid bonding, or for procreation).
• as a check prior to or during pregnancy, to prevent harm to the baby
• as a check after birth, to check that the baby has not caught an STI from the mother
• to prevent the use of infected donated blood or organs
• as part of the process of contact tracing from a known infected individual
• as part of mass epidemiological surveillance

Not all STIs are symptomatic, and symptoms may not appear immediately after infection. In some instances a disease can be carried with no symptoms, which leaves a greater risk of passing the disease on to others. Depending on the disease, some untreated STIs can lead to infertility, chronic pain or even death.^[13] Early identification and treatment results in less chance to spread disease, and for some conditions may improve the outcomes of treatment.

There is often a window period after initial infection during which an STI test will be negative. During this period the infection may be transmissible. The duration of this period varies depending on the infection and the test.

Treatment

High risk exposure such as what occurs in rape cases may be treated prophylacticly using antibiotic combinations such as azithromycin, cefixime, and metronidazole.

An option for treating partners of patients (index cases) diagnosed with chlamydia or gonorrhea is patient-delivered partner therapy (PDT or PDPT), which is the clinical practice of treating the sex partners of index cases by providing prescriptions or medications to the patient to take to his/her partner without the health care provider first examining the partner.^[14]

Epidemiology

Disability-adjusted life year for STDs excluding HIV per 100,000 inhabitants.

     no data      ≤  25      25-50      50-75      75-100      100-200      200-300      300-400      400-500      500-750      750-1000      1000-2000      ≥  2000

STD incidence rates remain high in most of the world, despite diagnostic and therapeutic advances that can rapidly render patients with many STDs noninfectious and cure most. In many cultures, changing sexual morals and oral contraceptive use have eliminated traditional sexual restraints, especially for women, and both physicians and patients have difficulty dealing openly and candidly with sexual issues. Additionally, development and spread of drug-resistant bacteria (e.g., penicillin-resistant gonococci) makes some STDs harder to cure. The effect of travel is most dramatically illustrated by the rapid spread of the AIDS virus (HIV-1) from Africa to Europe and the Americas in the late 1970s.^[15]

Commonly reported prevalences of STIs among sexually active adolescent girls both with and without lower genital tract symptoms include chlamydia (10–25%), gonorrhea (3–18%), syphilis (0–3%), Trichomonas vaginalis (8–16%), and herpes simplex virus (2–12%).^{[citation needed]} Among adolescent boys with no symptoms of urethritis, isolation rates include chlamydia (9–11%) and gonorrhea (2–3%).^{[citation needed]}

In 1996, the World Health Organization estimated that more than 1 million people were being infected daily. About 60% of these infections occur in young people <25 years of age, and of these 30% are <20 years. Between the ages of 14 and 19, STDs occur more frequently in girls than boys by a ratio of nearly 2:1; this equalizes by age 20. An estimated 340 million new cases of syphilis, gonorrhea, chlamydia and trichomoniasis occurred throughout the world in 1999.^[16][17]

History

American propaganda poster targeted at World War II soldiers and sailors appealed to their patriotism in urging them to protect themselves. The text at the bottom of the poster reads, "You can't beat the Axis if you get VD." Images of women were used to catch the eye on many VD posters.

Prior to the invention of modern medicines, sexually transmitted diseases were generally incurable, and treatment was limited to treating the symptoms of the disease. The first voluntary hospital for venereal diseases was founded in 1746 at London Lock Hospital.^[18] Treatment was not always voluntary: in the second half of the 19th century, the Contagious Diseases Act was used to arrest suspected prostitutes.

The first effective treatment for a sexually transmitted disease was salvarsan, a treatment for syphilis. With the discovery of antibiotics, a large number of sexually transmitted diseases became easily curable, and this, combined with effective public health campaigns against STDs, led to a public perception during the 1960s and 1970s that they have ceased to be a serious medical threat.

During this period, the importance of contact tracing in treating STIs was recognized. By tracing the sexual partners of infected individuals, testing them for infection, treating the infected and tracing their contacts in turn, STI clinics could be very effective at suppressing infections in the general population.

In the 1980s, first genital herpes and then AIDS emerged into the public consciousness as sexually transmitted diseases that could not be cured by modern medicine. AIDS in particular has a long asymptomatic period — during which time HIV (the human immunodeficiency virus, which causes AIDS) can replicate and the disease can be transmitted to others — followed by a symptomatic period, which leads rapidly to death unless treated. Recognition that AIDS threatened a global pandemic led to public information campaigns and the development of treatments that allow AIDS to be managed by suppressing the replication of HIV for as long as possible. Contact tracing continues to be an important measure, even when diseases are incurable, as it helps to contain infection.

See also

• Bugchasing and giftgiving
• Microbicide
• STD Wizard
• Transmission (medicine)
• Zoophilia and health
• Autoimmunity, Autoimmune disease

References

1. ^ Are sexually transmitted infections (STIs) different from sexually transmitted diseases (STDs)?, Frequently asked questions (FAQ) About Sexually Transmitted Diseases (STDs), Ethiopian AIDS Resource Center
2. ^ Cook H, Furuya E, Larson E, Vasquez G, Lowy F (2007). "Heterosexual transmission of community-associated methicillin-resistant Staphylococcus aureus". Clin Infect Dis 44 (3): 410–3. doi:10.1086/510681+. PMID 17205449. http://www.journals.uchicago.edu/cgi-bin/resolve?CID40836. 
3. ^ Adenoviruses - Stanford University
4. ^ Workowski K, Berman S (2006). "Sexually transmitted diseases treatment guidelines, 2006.". MMWR Recomm Rep 55 (RR-11): 1–94. PMID 16888612. http://www.cdc.gov/mmwr/PDF/rr/rr5511.pdf. 
5. ^ Wu J, Chen C, Sheen I, Lee S, Tzeng H, Choo K (1995). "Evidence of transmission of hepatitis D virus to spouses from sequence analysis of the viral genome.". Hepatology 22 (6): 1656–60. PMID 7489970. 
6. ^ Farci P (2003). "Delta hepatitis: an update.". J Hepatol 39 (Suppl 1): S212–9. doi:10.1016/S0168-8278(03)00331-3. PMID 14708706. 
7. ^ Shukla N, Poles M (2004). "Hepatitis B virus infection: co-infection with hepatitis C virus, hepatitis D virus, and human immunodeficiency virus.". Clin Liver Dis 8 (2): 445–60, viii. doi:10.1016/j.cld.2004.02.005. PMID 15481349. 
8. ^ "Cold sores 'an Alzheimer's risk'". BBC. http://news.bbc.co.uk/2/hi/health/7770680.stm. Retrieved 2008-12-12. 
9. ^ Virus Pathogenesis, Microbiology Bytes
10. ^ HIV/AIDS Glossary, World Bank
11. ^ Safe Sex Chart, violet blue: open source sex
12. ^ Wilkinson D, Ramjee G, Tholandi M, Rutherford G (2002). "Nonoxynol-9 for preventing vaginal acquisition of sexually transmitted infections by women from men". Cochrane Database Syst Rev (4): CD003939. doi:10.1002/14651858.CD003939. PMID 12519623. 
13. ^ "Male STI check-up video". Channel 4. 2008. http://sexperienceuk.channel4.com/education/about/male-sti-check-up. Retrieved 2009-01-22. 
14. ^ Expedited Partner Therapy in the Management of Sexually Transmitted Diseases (2 February 2006) U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES PUBLIC HEALTH SERVICE. Centers for Disease Control and Prevention National Center for HIV, STD, and TB Prevention
15. ^ Mary-Ann Shafer, Anna-Barbara Moscicki (2006). Sexually Transmitted Infections, 2006.. pp. 1–8. 
16. ^ STD Statistics Worldwide
17. ^ U.S. Medicine Information Central
18. ^ Archives in London and the M25 area (AIM25) London Lock Hospital records

External links

• Border Stories: Sex workers and HIV/AIDS in Tijuana, Mexico (VIDEO)
• SexInfo's Sexually Transmitted Infections Overview at University of California, Santa Barbara
• STD photo library at Dermnet
• Microbicides— Information from Our Bodies, Ourselves on the place of microbicides in the future of STI prevention.
• UNFPA: Breaking the Cycle of Sexually Transmitted Infections at UNFPA
• Dejucq N, Jégou B (June 2001). "Viruses in the mammalian male genital tract and their effects on the reproductive system". Microbiol. Mol. Biol. Rev. 65 (2): 208–31 ; first and second pages, table of contents. doi:10.1128/MMBR.65.2.208-231.2001. PMID 11381100. 
• Sexually Transmitted Infections from the National Institute of Allergy and Infectious Diseases
• "Sexual networks: implications for the transmission of sexually transmitted infections" at Massachusetts Institute of Technology
• "SxCheck 101, Basic Safe Sex Practices" (video). SxCheck. 2007. https://www.sxcheck.com/view/test/Sx101. 

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