Sexually transmitted diseases (STDs) affect men and women of all backgrounds and economic levels. CDC estimates that 19 million new infections occur each year, almost half of them among young people ages 15 to 24 1.
Despite the fact that STDs are extremely widespread and add an estimated $14.7 billion to the nation's healthcare costs each year 2, most people in the United States remain unaware of the risk and consequences of all but the most prominent STD—HIV, the virus that causes AIDS.
Many people are aware of the most prominent STD—HIV. However, many other STDs affect millions of men and women each year. Many of these STDs initially cause no symptoms, especially in women. When symptoms develop, they may be confused with those of other diseases that are not transmitted through sexual contact. STDs can still be transmitted from person to person even if they do not show symptoms. Furthermore, health problems caused by STDs tend to be more severe for women than for men.
Below are descriptions of several of the most common STDs, including information about incidence, symptoms (if any), and treatment.
Acquired Immune Deficiency Syndrome (AIDS)
Acquired immunodeficiency syndrome (AIDS) was first reported in the United States in 1981. Since the beginning of the epidemic through 2006, an estimated 1,014,797 people have developed AIDS in the United States and dependent areas 3. AIDS is caused by the human immunodeficiency virus (HIV), a virus that destroys the body's ability to fight off infection.
People who have AIDS are very susceptible to many life-threatening diseases, called opportunistic infections, and to certain forms of cancer. Transmission of the virus primarily occurs during unprotected sexual activity and by sharing needles used to inject intravenous drugs.
Learn more about AIDS and HIV. En Español.
Chancroid
Chancroid ("SHAN-kroid") is a bacterial infection caused by Haemophilus ducreyi, which is spread by sexual contact and results in genital ulcers. The disease is found primarily in developing and third world countries. Only a few hundred cases a year are diagnosed in the United States. The majority of individuals in the United States diagnosed with chancroid have traveled outside the country to areas where the disease is known to occur frequently 4.
The infection begins with the appearance of painful open sores on the genitals, sometimes accompanied by swollen, tender lymph nodes in the groin. These symptoms occur within a week after exposure. Symptoms in women are often less noticeable and may be limited to painful urination or defecation, painful intercourse, rectal bleeding, or vaginal discharge. Chancroid lesions may be difficult to distinguish from ulcers caused by genital herpes or syphilis. A physician must therefore diagnose the infection by excluding other diseases with similar symptoms. Chancroid is one of the genital ulcer diseases that may be associated with an increased risk of transmission of the human immunodeficiency virus (HIV), the cause of AIDS.
People with chancroid can be treated effectively with one of several antibiotics.
Learn more about chancroid infection. En Español.
Chlamydia
Chlamydial ("kla-MID-ee-uhl") infection is a common sexually transmitted disease (STD) caused by the bacterium Chlamydia trachomatis. Chlamydia is the most frequently reported bacterial sexually transmitted disease in the United States. An estimated 2,291,000 noninstitutionalized U.S. civilians ages 14–39 are infected with chlamydia 5. Underreporting is substantial because most people with chlamydia are not aware of their infections and do not seek testing.
Chlamydia can be transmitted during vaginal, oral, or anal sexual contact with an infected partner. A pregnant woman may pass the infection to her newborn during delivery, with subsequent neonatal eye infection or pneumonia. Even though symptoms of chlamydia are usually mild or absent, it can damage a woman's reproductive organs and cause serious complications. Irreversible damage, including infertility, can occur "silently" before a woman ever recognizes a problem. Chlamydia also can cause discharge from the penis of an infected man, although complications among men are rare.
Pelvic inflammatory disease (PID), a serious complication of chlamydial infection, has emerged as a major cause of infertility among women of childbearing age.
Chlamydia can be easily treated and cured with antibiotics.
Learn more about chlamydial infection. En Español.
Genital Herpes/HSV
Genital herpes is a contagious viral infection caused by the herpes simplex virus (HSV) which has affected an estimated one out of five (or 45 million) Americans. There are two types of HSV: herpes simplex viruses type 1 (HSV-1) or type 2 (HSV-2). Both can cause genital herpes, although most genital herpes is caused by HSV-2. Genital HSV-2 infection is more common in women (approximately one out of four women) than in men (almost one out of eight) 6.
HSV-1 most commonly causes sores on the lips (known as fever blisters or cold sores), but it can cause genital infections through oral-genital or genital-genital contact. HSV-2 most often causes genital sores, but it also can infect the mouth. Both HSV-1 and HSV-2 can produce sores in and around the vaginal area, on the penis, around the anal opening, and on the buttocks or thighs. Occasionally, sores also appear on other parts of the body where broken skin has come into contact with HSV. The virus remains in certain nerve cells of the body for life, causing periodic symptoms in some people.
Genital herpes infection usually is acquired by sexual contact with someone who unknowingly is having an asymptomatic outbreak of herpes sores in the genital area. People with oral herpes can transmit the infection to the genital area of a partner during oral-genital sex. Herpes infections also can be transmitted by a person who is infected with HSV who has noticeable symptoms.
There is no treatment that can cure herpes, but antiviral medications can shorten and prevent outbreaks during the period of time the person takes the medication.
Learn more about genital herpes. En Español.
Genital HPV Infection
Human papillomavirus (HPV) is one of the most common causes of STD in the world. Experts estimate that 20 million Americans are infected with HPV, and the frequency of infection and disease appears to be increasing. At least 50 percent of sexually active men and women acquire genital HPV infection at some point in their lives 7.
HPV is the name of a group of viruses that includes more than 100 different strains or types. More than 40 of these viruses are sexually transmitted, and they can infect the genital area of men and women including the skin of the penis, vulva (area outside the vagina), or anus, and the linings of the vagina, cervix, or rectum 7. Low-risk types of HPV cause genital warts, the most recognizable sign of genital HPV infection. Other high-risk types of HPV cause cervical cancer and other genital cancers.
Most people with HPV do not develop symptoms or health problems. In 90 percent of cases, the body's immune system clears the HPV infection naturally within 2 years 7.
A vaccine, Gardasil, has been developed to prevent cervical cancer, precancerous genital lesions, and genital warts due to genital HPV. It is effective in preventing four HPV types, which cause up to 70 percent of cervical cancers and 90 percent of genital warts 8.
Learn more about genital warts and HPV. En Español.
Gonorrhea
Gonorrhea (gone-or-REE-uh) is caused by Neisseria gonorrhoeae, a bacterium that can grow and multiply easily in the warm, moist areas of the reproductive tract. CDC estimates that more than 700,000 persons in the United States get new gonorrheal infections each year. Only about half of these infections are reported to CDC 9.
The most common symptoms of infection are a discharge from the vagina or penis and painful or difficult urination. The most common and serious complications occur in women and, as with chlamydial infection, these complications include pelvic inflammatory disease (PID), ectopic pregnancy, and infertility.
Gonorrhea can grow in the cervix (opening to the womb), uterus (womb), and fallopian tubes (egg canals) in women, and in the urethra (urine canal) in women and men. The bacterium can also grow in the mouth, throat, eyes, and anus. It can be life-threatening if it spreads to the blood or joints. In addition, people with gonorrhea can more easily contract HIV, the virus that causes AIDS. HIV-infected people with gonorrhea are more likely to transmit HIV to someone else.
Several antibiotics can successfully cure gonorrhea in adolescents and adults. However, antibiotic-resistant strains of gonorrhea are increasing in many areas of the world, including the United States, and successful treatment of gonorrhea is becoming more difficult. New antibiotics or combinations of drugs must be used to treat these resistant strains.
Learn more about gonorrhea. En Español.
Syphilis
Syphilis (SIF·i·lis) is caused by the bacterium Treponema pallidum. The incidence of syphilis has increased and decreased dramatically in recent years, and in the United States, health officials reported more than 36,000 cases of syphilis in 2006. Between 2005 and 2006, the number of reported primary and secondary (P&S) syphilis cases increased 11.8 percent. P&S rates have increased in males each year between 2000 and 2006 from 2.6 to 5.7 and among females between 2004 and 2006. In 2006, 64 percent of reported P&S syphilis cases were among men who have sex with men (MSM) 10.
Syphilis is passed from person to person through direct contact with syphilis sore. The first symptoms of syphilis infection may go undetected because they are very mild and disappear spontaneously. The initial symptom is a chancre (genital sore); it is usually a painless open sore that most often appears on the penis or around or in the vagina. It can also occur near the mouth, anus, or on the hands. Transmission of the organism occurs during vaginal, anal, or oral sex. Pregnant women with the disease can pass it to the babies they are carrying.
If untreated, syphilis may go on to more advanced stages, including a transient rash, and eventually can cause serious involvement of the brain, nerves, eyes, heart, blood vessels, liver, bones, and joints. The full course of the disease can take years.
Chancres caused by syphilis make it easier to transmit and acquire HIV infection sexually. There is an estimated two- to fivefold increased risk of acquiring HIV infection when syphilis is present 10.
Penicillin remains the most effective drug to treat people with syphilis.
Learn more about syphilis. En Español.
Trichomoniasis
Trichomoniasis (trick-oh-moe-NYE-uh-sis) is caused by the single-celled protozoan parasite, Trichomonas vaginalis. It is the most common curable STD in young, sexually active women, and it affects men as well although symptoms are most common in women. An estimated 7.4 million new cases occur each year 11.
The vagina is the most common site of infection in women, and the urethra (urine canal) is the most common site of infection in men. The parasite is sexually transmitted through penis-to-vagina intercourse or vulva-to-vulva (the genital area outside the vagina) contact with an infected partner. Women can acquire the disease from infected men or women, but men usually contract it only from infected women.
Most men with trichomoniasis do not have signs or symptoms; however, some men may temporarily have an irritation inside the penis, mild discharge, or slight burning after urination or ejaculation. Some women have signs or symptoms of infection which include a frothy, yellow-green vaginal discharge with a strong odor. The infection also may cause discomfort during intercourse and urination, as well as irritation and itching of the female genital area.
Trichomoniasis can usually be cured with prescription drugs, either metronidazole or tinidazole, given by mouth in a single dose.
Learn more about trichomoniasis. En Español.
Viral Hepatitis
Hepatitis A is a liver disease caused by the hepatitis A virus (HAV). HAV infection produces a self-limited disease that does not result in chronic infection or chronic liver disease. HAV infection is primarily transmitted by the fecal-oral route, by either person-to-person contact or through consumption of contaminated food or water. Hepatitis A vaccination is the most effective measure to prevent HAV infection and is recommended for all children at age 1, certain international travelers, and others at risk for HAV infection.
Hepatitis B is a serious liver infection caused by hepatitis B virus (HBV). HBV infection can cause acute illness and lead to chronic or lifelong infection, cirrhosis (scarring) of the liver, liver cancer, liver failure, and death. HBV is transmitted through percutaneous (puncture through the skin) or mucosal contact with infectious blood or body fluids. Hepatitis B vaccination is the most effective measure to prevent HBV infection and its consequences and is recommended for all infants and others at risk for HBV infection.
Hepatitis C is a liver disease caused by the hepatitis C virus (HCV) that sometimes results in an acute illness, but most often becomes a silent, chronic infection that can lead to cirrhosis (scarring) of the liver, liver failure, liver cancer, and death. Chronic HCV infection develops in a majority of HCV-infected persons, most of whom do not know they are infected since they have no symptoms. HCV is spread by contact with the blood of an infected person. There is no vaccine for hepatitis C.
Hepatitis D is a serious liver disease caused by the hepatitis D virus (HDV), and only occurs in people already infected with hepatitis B, since HDV needs the hepatitis B virus to replicate. HDV is transmitted through percutaneous (puncture through the skin) or mucosal contact with infectious blood.
Hepatitis E is a liver infection caused by the hepatitis E virus (HEV) that usually results in a self-limited disease. HEV infection is primarily transmitted by the fecal-oral route, mostly through consumption of contaminated water. While rare in the United States, hepatitis E is common in many parts of the world. There is currently no approved vaccine for hepatitis E.
Learn more about viral hepatitis.
Other STDs
Other diseases that may be sexually transmitted include bacterial vaginosis, scabies, pubic lice, and Pelvic Inflammatory Disease (PID).
In the United States alone, an estimated 19 million new cases of STDs are reported each year 1. This table shows the incidence and prevalence of some of the most common STDs.
STDs can result in irreparable lifetime damage, including blindness, bone deformities, mental retardation, and death for infants infected by their mothers during gestation or birth.
In women, STDs can lead to pelvic inflammatory disease (PID), infertility, potentially fatal ectopic pregnancies, and cancer of the reproductive tract.
As the lead agency for STD prevention in the United States, CDC is tasked with providing national leadership through research, policy development, and support of effective services to prevent STDs (including HIV infection) and their complications, such as enhanced HIV transmission, infertility, adverse outcomes of pregnancy, and reproductive tract cancer. The Division of STD Prevention, part of CDC's National Center for HIV, Viral Hepatitis, STD, and TB Prevention, coordinates CDC's STD prevention efforts.
