Sexually Transmitted Diseases (STDs)
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Sexually transmitted diseases (or STDs) are a varied group of infections that usually are passed from person to person by sexual contact. Some also spread from mother to child during pregnancy or childbirth. Widespread around the world, STDs are particularly common among people in their teens and early twenties. STDs range in severity from pubic lice, which usually cause only discomfort, to AIDS, which has caused millions of deaths in a worldwide epidemic.
Sexual contact between people is one important way that many diseasecausing organisms spread. More than 30 bacterial, viral, and parasitic diseases can pass from person to person in this way. For some of these, sexual contact is the main route of transmission. These are the illnesses we generally call sexually transmitted diseases (STDs).
Most STDs primarily affect only the sexual organs and other parts of the reproductive system. That is true of chlamydial (kla-MID-i-al) infections, gonorrhea (gon-o-REE-a), genital herpes, genital warts, and trichomoniasis (trik-o-mo-NY-a-sis). Other STDs may enter through the sexual organs but affect other parts of the body. That is what happens in AIDS and syphilis.
Besides AIDS, some STDs can have serious complications, especially for women. Chlamydia and gonorrhea often cause no symptoms in women (and sometimes in men), which means they can easily go untreated. But
If syphilis goes untreated in men or women, it can cause fatal heart problems, as well as blindness, deafness, and insanity, many years later.
Are All Infections of the Genital Tract Spread by
No. For instance, yeast infections of the genital tract usually do not involve sexual contact. Most often, the yeast (a kind of fungus) spreads from a person's own skin or intestinal tract, where it does no harm, into the person's genital tract, where it can cause symptoms. So a person could get such an infection even if he or she had never engaged in sexual activity. The most common of these yeast infections is called candidiasis (can-di-DI-a-sis).
Who Is at Risk for STDs?
Just about anyone who has sexual contact with another person can get an STD. People who are infected with one STD are likely to have other STDs as well. Once cured, they also are at higher risk of getting infected again.
STDs are particularly common among young people, aged 15 to 24. Experts see several reasons for this: Young people are less likely to be married, so if they engage in sex, they may tend to have more sexual partners than older people. Young people more often fail to use condoms during sexual activity, even though condoms can protect a person from most sexually transmitted diseases. Young people may be too embarrassed, too short of money, or too worried about privacy to get regular checkups or to get prompt medical treatment for STDs. As a result, they may stay infected—and may be able to infect others—for longer than necessary.
In general, people run a higher than usual risk of getting infected if they begin sexual activity at an early age, have a number of sexual partners, do not always use condoms, and do not get regular medical checkups. But even a person who has sex only one time, with only one partner, can get an STD if his or her partner is infected. The only clear way to prevent getting an STD is to abstain from sexual activity.
How Do STDs Spread?
People with STDs often do not realize they are infected, and so they spread the disease to others, including people they love most—wives, husbands, and children.
These diseases can spread through sexual contact between people of the opposite sex (heterosexual sex) or between people of the same sex (homosexual sex). Sexual activities that can spread STDs include sexual intercourse, anal sex, and oralgenital sex.
Other routes of transmission
STDs also sometimes spread in nonsexual ways. Many of them—including HIV, gonorrhea, chlamydia, syphilis, and genital herpes—can be spread from mother to baby during pregnancy or childbirth. HIV can also spread through breastfeeding.
HIV, the virus that causes AIDS, can spread if an infected person shares needles, or if contaminated blood is given in a blood transfusion. In the United States, strict testing has made blood transfusions extremely safe, but the risk may be higher in some other countries.
STDs that cause sores on the skin, such as genital herpes, syphilis, and chancroid * , can spread sometimes if the sores touch another person's skin. The sores also can serve as a way for HIV to enter the body, making infection with the AIDS virus more likely. Preventing or treating these sores is important in the prevention of AIDS.
Most STDs cannot be spread by contact with an object, such as a toilet seat. One exception is trichomoniasis, which is thought to spread sometimes through towels or bathing suits recently used by an infected person.
What Happens When People Get STDs?
Several of the most common of these diseases—chlamydia, gonorrhea, and trichomoniasis—can cause pain during urination and a pus-like discharge from the sexual organs. In many cases, however, there are no symptoms in these illnesses. Several other STDs cause sores or blisters in the genital region. These include syphilis, genital herpes, and chancroid. The symptoms of HIV/AIDS include getting frequent fungal and parasitic infections.
From the symptoms and a look at any skin sores that may be present, a doctor may suspect an STD. Tests of various kinds can usually tell for sure which infection, if any, a person has.
Because chlamydia and gonorrhea are very common in young women, but often cause no symptoms and can lead to infertility, doctors recommend that young women who engage in sexual activity get tested routinely for these illnesses so they can be treated.
In addition, anyone whose sexual partner has been diagnosed with an STD, or whose partner has symptoms of an STD, should be tested and treated if they are also infected.
How Are STDs Treated?
STDs can be divided into curable illnesses and illnesses that can be treated but not cured.
Curable illnesses usually are caused by bacteria or parasites. These include chlamydia, gonorrhea, syphilis, and chancroid, all caused by bacteria, and trichomoniasis, caused by a parasite. These can be cured with medication. Syphilis and gonorrhea, in fact, often can be cured by a single swallow or shot of medicine.
* chancroid (SHANG-kroid) is a bacterial infection that causes painful sores in the genital region. Relatively rare in the United States, it mostly occurs in tropical and subtropical areas.
Non-STDs: A Matter of Definition
Many infections can spread through sexual contact but usually spread in other ways. These illnesses generally are not classified as sexually transmitted diseases. They include:
- Hepatitis B and cytomegalovirus, viruses that usually spread through blood
- Bacteria like salmonella, parasites like amebas, and the virus Hepatitis A, all of which usually spread through water or food that has been contaminated with feces from an infected person
Ilnesses that are treatable, but not curable, usually are caused by viruses. These include HIV/AIDS, genital herpes, and genital warts. These cannot be cured with drugs, because the viruses remain in the body. But, in most cases, medication or other treatment can reduce symptoms. In the case of people with HIV infection, medication can increase the life span and the quality of life.
How Can STDs Be Prevented?
Abstinence and safer sex
The only sure way to avoid getting an STD is not to have sexual contact with anyone (called abstention or abstinence).
For people who do engage in sex, the safest relationship is when two people who are not infected have sexual contact only with each other. The problem is that it is impossible to know for sure whether someone is infected or not. People may not always tell the truth about their sexual behavior in the past—or they may mistakenly think they were protected in the past. Many people with an STD do not know or believe they have one.
That is one reason why health officials recommend that people who engage in sex always use latex condoms unless they are trying to get pregnant. Using latex condoms can lower the risk of getting an STD, but the condoms must be used properly, and they must be used every time a person engages in sexual activity.
Education and awareness
At the public health level, education is an important part of preventing STDs. Awareness about the need to prevent STDs has greatly increased in recent decades, largely because of the emergence of AIDS. Information about how to prevent STDs is now widely published in the media and taught in schools. Young people are being urged to abstain from sex or to use condoms if they are sexually active.
In addition, when a person is diagnosed with an STD, doctors or health officials try to locate the person's sexual partners so they can be tested and treated. This kind of confidential "contact tracing" is done without revealing the infected person's name. It prevents the person's sexual contacts from unknowingly spreading the disease.
But the only sure way to prevent getting an STD is to abstain from sex.
The U.S. and the World
Sexually transmitted diseases take a heavy toll throughout the world. By the end of 1998, AIDS had killed almost 14 million people worldwide, including more than 400,000 people in the United States. More than 33 million people were living with HIV infection, mostly in underdeveloped countries in Africa and Asia.
While other sexually transmitted diseases seldom cause death, they do cause a heavy burden of illness. In 1995, the World Health Organization estimated that 333 million new cases of curable STDs occurred. That included:
- 89 million cases of chlamydial infection
- 62 million cases of gonorrhea
- 12 million cases of syphilis
- 170 million cases of trichomaniasis
Throughout the world, including the United States, STDs tend to be more common in urban, unmarried teenagers and in young adults.
In the United States, it is estimated that most adults will be infected with a sexually transmitted disease at some time, although they may not know it. Some form of the human papillomavirus, for instance, infects most Americans. Some strains of human papillomavirus cause genital warts; others can promote cervical cancer. And more than 1 in 5 Americans is thought to be infected with the virus that causes genital herpes.
Of the bacterial STDs, chlamydia is the most common. It is estimated to cause about 4 million cases a year in the United States, although only about 10 percent of those get reported to health agencies. It is thought that 1 in 10 adolescent women and 1 in 20 adult women of child-bearing age are infected.
Brodman, Michael, M.D., John Thacker, and Rachel Kranz. Straight Talk About Sexually Transmitted Diseases. New York: Facts on File, 1998. This book focuses on prevention for young people and includes explicit discussion of more and less risky sexual activity.
The National Institutes of Health posts information about sexually
transmitted diseases on its website.
The U.S. Centers for Disease Control and Prevention (CDC), 1600 Clifton
Road, N.E., Atlanta, GA 30333, has a National STD Hotline that is open
from 8:00 AM to 11:00 PM EST.
The CDC also posts information about sexually transmitted diseases at
The American Social Health Association posts a
Sexual Health Glossary
and fact sheets about STDs at its website.