Sexually transmitted diseases (STDs) are infections that pass from one person to another through sexual contact, which includes
oral, genital, or anal intercourse.
What Are STDs?
STDs can be caused by bacteria, viruses, or parasites. Although the symptoms of a particular STD depend on the specific
infection, many STDs cause vaginitis (vah-jih-NYE-tis), an inflammation of the vagina often accompanied by an abnormal discharge
(fluid released from the body), and urethritis (yoo-ree-THRY-tis), an inflammation of the urethra (the tube through which
urine passes from the bladder to the outside of the body), which can make urination painful. Several STDs can produce blisters
or sores on the penis, vagina, rectum, or buttocks. In women, some STDs may spread to the cervix*, a condition called cervicitis
(sir-vih-SYE-tis), or to the uterus* and fallopian tubes*, a condition known as pelvic inflammatory disease (PID). In men
STDs may spread to the testicle (causing epididymitis*) or prostate* (causing prostatitis, inflammation of the prostate).
It is not uncommon for several STDs to occur in the same person, and the presence of an STD can increase the risk of contracting
infection with human immunodeficiency (ih-myoo-no-dih-FIH-shen-see) virus (HIV), the virus that causes acquired immunodeficiency
syndrome (AIDS), from an infected partner.
How Common Are They?
STDs are common in the United States; between 13 million and 15 million new cases are diagnosed every year. Despite the
fact that much information is available about preventing these infections and limiting their spread, the number of people
infected is growing, and about two-thirds of cases are reported in people under the age of 25 years.
*cervix (SIR-viks) is the lower, narrow end of the uterus that opens into the vagina.
*uterus (YOO-teh-rus) is the muscular, pear-shaped internal organ in a woman where a baby develops until birth.
*fallopian (fah-LO-pee-uhn) tubes are the two slender tubes that connect the ovaries and the uterus in females. They carry
the ova, or eggs, from the ovaries to the uterus.
*epididymitis (eh-pih-dih-duh-MY-tis) is a painful inflammation of the epididymis, a structure attached to the testicles.
*prostate (PRAH-state) is a male reproductive gland located near where the bladder joins the urethra. The prostate produces
the fluid part of semen.
Are STDs Contagious?
STDs are contagious and are transmitted through sexual contact that involves vaginal, anal, or oral sex. The diseases
can spread between people of the opposite sex or people of the same sex. The germs that cause many STDs move from person to
person through semen (the sperm-containing whitish fluid produced by the male reproductive tract), vaginal (VAH-jih-nul) fluids,
or blood. Other STDs, like herpes and genital warts, can spread by intimate skin-to-skin contact, often with sores the disease
causes. Certain STDs can pass from a mother to her baby during pregnancy or childbirth. STDs do not pass from one person to
another by simply hugging, shaking hands, or sharing utensils.
What Are Some Common STDs?
Gonorrhea (gah-nuh-REE-uh) is caused by the bacterium Neisseria gonorrhoeae (nye-SEER-e-uh gah-no-REE-eye). It may not
produce any symptoms in women who are infected. When symptoms are present, they include vaginal discharge and pain when urinating.
Lower belly pain usually occurs when the infection has spread past the cervix and caused PID. Most men with gonorrhea have
a discharge from the penis and pain when they urinate. Gonorrhea is treated with antibiotics that kill the bacteria.
Syphilis (SIH-fih-lis) is caused by the bacterium Treponema pallidum (treh-puh-NEE-muh PAL-ih-dum). It is different from
many other STDs, because there are distinct stages to the illness. In the first stage, a small, hard sore called a chancre
(SHANG-ker) appears where the bacteria entered the body. In the next stage, a red or brown rash develops, sometimes on the
palms of the hands and soles of the feet; in some cases, patients also may have a fever, swollen lymph nodes*, muscle aches,
and headaches. If the disease goes untreated, it can progress to the third and most serious stage, when it may damage the
bones, organs, and nervous system, which can result in blindness, paralysis*, dementia*, heart problems, and sometimes even
death. Like gonorrhea, syphilis can be treated effectively with antibiotics. More than 31,000 cases of syphilis were reported
in the United States in 2000.
Herpes simplex virus
Herpes simplex (HER-peez SIM-plex) virus causes herpes. There are two types of herpes, type 1 and type 2. Type 2 usually
spreads through sexual contact and causes genital herpes. In a person with genital herpes, small, painful blisters develop
on the vagina, cervix, penis, buttocks, or thighs. Once infection occurs, the herpes virus remains in the body and can recur
throughout a person's life. Antiviral medications may shorten outbreaks of symptoms and make them less severe, but they do
not kill the virus. In the United States an estimated 45 million people over the age of 12 have genital herpes infection.
Chlamydia (kla-MIH-dee-uh) is caused by the bacterium Chlamydia trachomatis (kla-MIH-dee-uh truh-KO-mah-tis), and in many
infected people it produces no symptoms. The most common symptoms in both men and women are discharge and pain when urinating.
Because infection with chlamydia may not be noticed, it can spread and produce other symptoms, including epididymitis in men
and PID in women. More than 700,000 cases were reported in the United States in 2000, but the actual number of new cases could
be 3 million to 4 million per year. A person with chlamydia can be treated effectively with antibiotics.
*lymph (LIMF) nodes are small, bean-shaped masses of tissue that contain immune system cells that fight harmful microorganisms.
Lymph nodes may swell during infections.
*paralysis (pah-RAH-luh-sis) is the loss or impairment of the ability to move some part of the body.
*dementia (dih-MEN-sha) is a loss of mental abilities, including memory, understanding, and judgment.
Infection with HIV damages immune system cells in the body that normally fight infections, leaving the body unable to
defend itself against a variety of illnesses. A person can be infected with HIV and not have AIDS, although most people with
HIV do end up developing AIDS. The first symptoms of HIV infection include fever, muscle aches, sore throat, and, in some
cases, a rash that looks somewhat like that of measles*. Other symptoms usually take much longer to appear, perhaps years,
and may include rapid weight loss, recurring fever, a dry cough, night sweats, pneumonia*, white spots on the tongue or throat,
long-lasting diarrhea, and skin rashes and yeast infections. A person with AIDS also may have memory loss, depression, and
Human papillomavirus, or HPV, of which there are over 50 types. HPV causes genital warts and is strongly associated with cervical
and penile cancers.
n the United States, there were more than 40,000 new cases of AIDS reported in 2000, and more than 850,000 people were living
with HIV in 2000. There have been more than 460,000 reported deaths related to AIDS in the United States since the disease
was first identified in the early 1980s. There is no cure for AIDS, but a combination of medications can help a person live
longer and have a better quality of life.
Genital and anal warts are caused by human papillomavirus (pah-pih-LO-mah-vy-rus), or HPV, a very common virus. The warts
are soft and skin-colored, and they can grow alone or in bunches on the genitals; on the skin around the genitals, rectum,
or buttocks; or in the vagina or cervix. Like herpes, genital warts can reappear again and again, because once this type of
virus enters the body, it remains there for life. Doctors can remove genital warts by freezing, burning, or cutting them off
or by coating them with medication that destroys the warts. In women, infection with HPV can affect the cells of the cervix,
which may lead to cervical cancer.
Trichomoniasis (trih-ko-mo-NYE-uh-sis) is a very common STD that is caused by a parasite. Most women with trichomoniasis
have a frothy, yellow, foul-smelling vaginal discharge, along with itching and irritation in the vagina and discomfort during
sex and urination. Men with this STD typically do not have symptoms; those who do have symptoms may feel irritation in the
penis or a burning sensation after they urinate or ejaculate*. More than 2 million cases are diagnosed each year in the United
States. Trichomoniasis can be treated with antibiotics.
*measles (ME-zuls) is a viral respiratory infection that is best known for the rash of large, flat, red blotches that
appear on the arms, face, neck, and body.
*pneumonia (nu-MO-nyah) is inflammation of the lung.
*ejaculate (e-JAH-kyoo-late) means to discharge semen from the penis.
Can STDs Be Prevented?
The only sure way to prevent STDs is not to have sexual contact with anyone. In most cases, it is impossible or very difficult
to tell whether another person has an STD. People may not always tell the truth about their sexual past, or they may have
an STD and not know it. For people who do have sex, the safest choices are to limit the number of sexual partners and to use
latex condoms. Latex condoms lower the risk of contracting many STDs, including HIV infection. Certain STDs such as genital
warts and herpes may present additional problems, because the warts or herpes blisters can be on the skin around the genitals
and condoms do not protect against them if the sores are not covered by the condom. Avoiding skin-to-skin contact is the best
option for preventing these kinds of STDs.
U.S. Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, Atlanta, GA 30333. The CDC provides fact sheets
and other information on STDs at its website.