Sexually Transmitted Diseases

VD, STDs, Venereal Disease

What are STDs?

Sexually transmitted diseases (STDs) are among the most common infectious diseases in the United States. Infectious diseases are defined as diseases that can be passed from one person to another.

STDs are normally spread through sexual activities, including vaginal intercourse, anal intercourse, oral sex (mouth-to-genital contact) or any other form of intimate contact involving genitals. The diseases can also be spread through sharing sexual devices that are not washed or covered with a condom. Many STDs can be passed from a mother to her infant before, during or after birth, during breastfeeding. Some STDs can even be passed through non-sexual contact with the skin of an infected person. In some cases, certain STDs (e.g., pubic lice, scabies) are also spread through contact with an infected person’s clothes, towels or linens. Although it is uncommon, some STDs (e.g., genital herpes) have also been spread through contact with toilet seats and hot tubs.

STDs can travel from person to person in bodily fluids, including semen, vaginal fluids and blood. Some can enter the body through tiny cuts or tears in the mouth, anus or genitals. STDs that are spread through blood, such as human immunodeficiency virus (HIV) and hepatitis, may also be transmitted through sharing needles used for injecting intravenous drugs.

According to the U.S. Centers for Disease Control and Prevention (CDC), approximately 15.3 million new cases of STDs are reported each year in the United States. However, many STDs go undiagnosed and unreported. Therefore, the CDC estimates that a total of 19 million STD infections occur in the United States each year.

Anyone engaging in sexual activity is at risk of contracting an STD. This includes sexual activity between a man and woman or between people of the same gender. However, certain populations are more likely to acquire the diseases. According to the CDC, STDs disproportionately affect women, infants, young people and minorities. Of these groups, young people are particularly affected. Nearly half of all STD cases occur among young adults between the ages of 15 and 24, and nearly two-thirds of all STDs occur in people under the age of 25.

STDs are passed more often from men to women than the reverse because the exposed surface area is larger in women. In addition, the vagina acts like a reservoir that prolongs contact with infectious fluids. Microscopic injuries during intercourse are also more common in women than in men.

The high rate of STD infection may be the result of many factors, including young adults becoming sexually active at a younger age. In addition, young people are more likely to have multiple sexual partners and are more likely to have unprotected sex.

Complications of the diseases vary. Although STDs are often linked with unpleasant symptoms, including sores and foul smelling discharge, they can cause a variety of serious complications such as liver failure, certain cancers and neurological problems. Infection with certain diseases may also result in death, with HIV being the deadliest STD.

In general, complications caused by STDs tend to be more severe for women. A common complication of many STDs in women is pelvic inflammatory disease (PID), which can result in chronic pelvic pain, infertility and ectopic pregnancy. Ectopic pregnancy is a potentially fatal condition in which a fertilized egg develops outside the uterus.

Women with sexually transmitted diseases can infect their infants before, during or after birth. Some STDs like syphilis cross the placenta, infecting the fetus while it is in the uterus. Others, like herpes, gonorrhea and chlamydia, can be transmitted during delivery as the infantpasses through the birth canal (vagina). In addition, HIV can infect the infant during breastfeeding.

Sexually transmitted diseases also increase a person’s risk of acquiring the HIV virus. According to the CDC, people who are infected with STDs are at least two to five times more likely to acquire HIV when exposed to the virus during sexual contact. The risk of infection is increased because the action of the disease in the body places tissues at risk for further infection. In addition, people with HIV who are also infected with another STD are more likely to transmit the HIV virus through sexual contact.

Types and differences of STDs

Sexually transmitted diseases (STDs) are caused by three types of organisms. These organisms include:


These are very small organisms that get nourishment from the person they infect (the host). Examples of sexually transmitted parasites include:

Pubic lice

Also known as “crabs” or Phthirus pubis, pubic lice are parasitic insects usually found in the genital area on pubic hair. However, they may occasionally be found on other areas of coarse body hair, including the legs, armpits, mustache, beard, eyebrows or eyelashes. Pubic lice are most often spread through sexual contact, including vaginal intercourse and anal intercourse.

Rarely, the parasites may also spread through contact with an infected person’s bed linens, towels or clothes. Pubic lice are most often found in adolescents, and are characterized by moderate to severe itching in the area covered by pubic hair. According to the National Institutes of Health (NIH), approximately 3 million new cases occur in the United States each year.


Trichomoniasis is caused by Trichomonas vaginalis, a single-celled parasite that most commonly affects the vagina in women and the urethra in men. Transmission may occur during penis-to-vagina or vulva-to-vulva contact. It may also be spread through contact with damp, moist objects such as towels or wet clothing. Trichomoniasis is one of the most common curable STDs in young women. Some experts believe that trichomoniasis may also increase the risk of human immunodeficiency virus (HIV) transmission.


Scabies is caused by infestation with Sarcoptes scabei, a microscopic mite. It may be transmitted through skin-to-skin contact, including vaginal and anal intercourse, or it may result from nonsexual contact such as sharing clothes, towels or bedding. Scabies is characterized by small bumps or rashes on the skin and intense itching. Possible complications include secondary infections caused by skin damage from frequent scratching.


These complex molecules invade the cells of their host, where they are capable of growing and multiplying. Viral STDs are commonly transmitted during sexual activity, including vaginal intercourse, anal intercourse and oral sex (mouth-to-genital contact).


HIV, the virus that causes AIDS, is carried in blood, semen, vaginal fluids and breast milk. In addition to being transmitted sexually, HIV may also be spread by sharing needles used to inject intravenous drugs or from mother to child (during delivery or breastfeeding). According to the U.S. Centers for Disease Control and Prevention (CDC), approximately 900,000 people in the United States are currently infected with HIV, which impairs the body’s ability to fight infection. As a result, people with AIDS are highly susceptible to many life-threatening diseases and certain forms of cancer. In the early 1980s, HIV was also transmitted via blood transfusions and blood products. However, all donated blood products, in addition to organs for transplant, are now screened for HIV in the United States and other developed countries.

Genital herpes

This STD is caused by the herpes simplex virus (HSV). The two types of HSV include type 1 (HSV1) and type 2 (HSV2). Both types can cause genital herpes but most cases are caused by HSV2. The viruses are usually spread through contact with sores during sexual activity. They may also be spread through contact with skin that does not appear to be broken or have a sore, or from an infected woman to her infant during delivery.

The herpes virus also causes the typical cold sore. Cold sores are usually caused by HSV1, but may also be caused by HSV2. Performing oral sex while having an active cold sore can cause transmission of the virus to the partner’s genital area. Rarely, genital herpes can also be transmitted through contact with a toilet seat or hot tub.

Many people do not experience any signs or symptoms of genital herpes, but the condition may be characterized by the appearance of blisters on or around the genitals. According to the CDC, genital herpes affects about 45 million Americans. Genital herpes increases the risk of HIV transmission.

Viral hepatitis

There are numerous types of hepatitis viruses, including the hepatitis A, B, C, D and E virus. Although the hepatitis B, C and D viruses can all be transmitted through sexual activity, the B virus is most easily transmitted in this manner. The CDC estimates that between 120,000 and 200,000 new cases of hepatitis B occur each year. Of these cases, as many as half are transmitted through sexual contact. Infection with the hepatitis B virus can result in severe complications including chronic hepatitis, cirrhosis and liver cancer.

Human papillomavirus (HPV)

HPV is caused by a group of more than 100 types of viruses, including the viruses that cause common skin warts. Of these various strains, more than 30 are sexually transmitted and live only in genital tissue. HPV may also be spread through skin-to-skin contact involving the genital area and, in rare cases, from mother to infant during delivery.

HPV usually causes no symptoms. However, some patients may develop small, flesh-colored bumps known as genital warts. Several types of HPV are associated with the development of cervical cancer in women. This cancer is common in women outside the United States, but its U.S. incidence has dropped because of regular monitoring through Pap smears. HPV can infect the vagina, penis, anus, rectum, mouth and throat. According to the CDC, approximately 20 million people are infected with HPV in the United States. A vaccine for the strains of HPV that are most likely to cause cervical cancer has been approved by the FDA for use in female adolescents and young adult females.


These single-celled organisms cling together in colonies to feed from the body of their host. They are commonly transmitted through sexual activity, including vaginal intercourse, anal intercourse and oral sex. Many sexually transmitted bacterial infections also increase the risk of HIV transmission. Examples of sexually transmitted bacterial infections include:


This STD is caused by the bacterium Chlamydia trachomatis. In addition to being transmitted sexually, chlamydia can also be passed from an infected woman to her baby during vaginal childbirth. In women, the bacteria typically infects the cervix and the urethra and may spread to the fallopian tubes and rectum. In men, the disease affects the penis and testicles. Following anal or oral sex, the rectum or throat may become infected.

Sexually active teenage girls and young women are particularly susceptible to infection because their cervixes are not fully mature, allowing bacteria to penetrate more easily. Left untreated, chlamydia may cause pelvic inflammatory disease (PID), a major cause of infertility and ectopic pregnancy. Complications among men are rare.


Gonorrhea is caused by the bacterium Neisseria gonorrhea, which can easily grow and multiply in warm, moist areas of the body. Such areas may include the cervix and uterus in women, the urethra in men, and the mouth, throat, eyes and anus in both men and women. In some cases, gonorrhea may spread further to the blood or joints. In addition to being transmitted through sexual contact, gonorrhea can be passed from a pregnant woman to her infant during delivery.

Gonorrhea is characterized by thick discharge from the vagina or penis. The most common and serious complications of the infection occur in women and include PID, ectopic pregnancy and infertility. In men, the disease can lead to epididymitis, a condition of the testicles that can result in infertility.


This STD is caused by the bacterium Treponema pallidum, which is passed through contact with syphilis sores. Sores mainly appear on the external genitals, vagina and anus or in the rectum. They may also appear on the lips, in the mouth or on the hands. Syphilis may also be passed from a woman to her child during delivery. Left untreated, syphilis may progress to a rash, and eventually affect the heart and central nervous system (brain and spinal cord).

The CDC estimates that more than 60 percent of all reported primary and secondary syphilis (early stages of the disease that indicate recent infection) cases occur among men who have sex with other men. Syphilis rates have declined in the past 50 years and now occur mostly in urban areas. They sometimes spike up in cycles and then decline again.


Chancroid is caused by the bacterium Haemophilus ducreyi. This sexually transmitted disease is primarily found in developing countries in Africa and Asia. It is generally rare in the United States, with only a few hundred cases diagnosed each year. However, chancroid occurs in periodic outbreaks in the United States, the last of which was in the 1980s. Chancroid is characterized by the development of one or more small bumps in the genital area that become ulcers within one day of their appearance. The lesions may resemble genital herpes or syphilis ulcers.

Granuloma inguinale

This STD is caused by the bacterium Calymmatobacterium granulomatis. It is characterized by the appearance of lesions in the genital or anal area. Granuloma inguinale is most common in southeast India, Guyana and New Guinea. It rarely occurs in the United States, with only about 100 cases being reported each year. According to the NIH, men are infected nearly twice as often as women, and most infections occur among people between the ages of 20 and 40.

Anal intercourse is considered the most frequent source of transmission. Complications may include destruction and scarring of the genitals, genital depigmentation (loss of pigment in the genital area) and permanent genital swelling. In some cases, the disease may spread throughout the body. This may result in death from secondary complications including heart failure, pneumonia or hemorrhage. If treated early, complications can be avoided.

Risk factors and causes of STDs

Any person participating in sexual activity is at risk of becoming infected with a sexually transmitted disease (STD). However, there are certain factors that increase this risk including:

  • Participating in unprotected vaginal intercourse, anal intercourse or oral sex (mouth-to-genital contact).
  • Having multiple sexual partners. The more sexual partners a person has, the greater their risk of being exposed to an STD. Having multiple partners also makes it less likely that a person knows about each partner’s sexual history and drug habits.
  • Having a sexual partner with a history of many sexual partners.
  • Not knowing the sexual history of all sexual partners.
  • Illegal intravenous drug use. HIV/AIDS and some other STDs can be transmitted by sharing needles.

Signs and symptoms of STDs

Common signs and symptoms of sexually transmitted diseases (STDs) include:

  • Lower abdominal pain
  • Painful urination or bowel movements
  • Unusual discharge from the vagina or penis
  • Pain in the pelvic area during intercourse
  • Burning or itching in the genital area
  • Sores, blisters or warts in the genital, anal or oral areas
  • Lumps in the genital or anal areas
  • Foul smell from the genital area

Other possible signs and symptoms of STDs include:

  • Pain in the anus (in people who engage in anal intercourse)
  • Sore throat (in people who engage in oral sex [mouth-to-genital contact])
  • Scaly rash on the palms of the hands and soles of the feet (e.g., syphilis)
  • Dark colored urine or loose, light-colored stool
  • Yellow eyes and skin (jaundice)
  • Swollen lymph nodes
  • Fever with body aches or night sweats
  • Unusual infections
  • Unexplained fatigue (extreme tiredness) or weight loss

It is recommended that people learn to recognize the common signs and symptoms of sexually transmitted diseases. If the symptoms develop, a physician should be contacted immediately. Many common STD symptoms, such as sores, rashes and discharge, disappear without treatment. However, this does not indicate that the condition has been cured. Many STDs continue to progress without symptoms, only to emerge at another point.

Some of the common signs and symptoms of STDs mimic those caused by urinary tract infections (UTI) and genital infections. As a result, sexually active people with a new sex partner, and those who are not in monogamous relationships, may want to be tested for STDs when symptoms of these other conditions develop.

Although the recognition of symptoms allows a disease to be diagnosed earlier, many STDs have no symptoms or have symptoms that are not easily recognizable. The lack of symptoms is especially common in women.

All sexually active people are encouraged to have regular medical checkups and STD screening tests. The earlier an STD is diagnosed, the earlier treatment for the disease can begin. Early treatment is important because STDs may cause serious complications if left untreated.

Diagnosis of sexually transmitted diseases

Sexually transmitted diseases (STDs) may be diagnosed before symptoms develop during routine medical checkups or when the patient requests testing. When symptoms are present, the physician or healthcare provider may perform a number of tests to determine the exact type of STD. Urine tests may also be used to screen for some STDs.

To diagnose an STD, the physician will take the patient’s medical history, including detailed information about their sexual history. The physician will then perform a complete physical examination, including, for women, a pelvic examination. During the exam, the physician will carefully inspect the genital area, oral cavity and rectum. If sores or discharge are present, the physician may use a swab to collect samples for examination. The samples will then be tested for the presence of various microorganisms.

During a woman’s pelvic exam, swabs of the vagina may be taken. A Pap smear, or a swab of the cervix, may also be taken. The samples will then be checked for infections. Urine tests and blood tests may be ordered to detect or rule out certain diseases, including HIV/AIDS and syphilis.

After an STD is diagnosed, the patient should inform present and past sexual partner(s) about the diagnosis. This is necessary because all sexual partners will require testing and treatment. Informing sexual partners also prevents the transmission of the disease to other people or the reinfection of partners who have already received treatment.

Treatment of sexually transmitted diseases

The method used to treat a sexually transmitted disease (STD) depends on the cause of the disease. STDs caused by bacteria, such as chlamydia, syphilis and gonorrhea, are usually treated with antibiotics. STDs caused by parasites are also treated with medications or over–the–counter drugs. Current medications allow for most STDs caused by bacteria and parasites to be cured when treated early.

STDs caused by viruses, such as HIV/AIDS, genital herpes and human papillomavirus (HPV), are treated differently then those caused by bacteria or parasites because usually they cannot be cured. Instead, medical treatment is used to control the disease. Drugs may be used to reduce the severity of symptoms and the frequency of outbreaks but they are often unsuccessful. For a virus such as HPV, which may cause the development of warts on the skin, treatment may focus on removing the warts with chemicals or surgery.

Having a curable STD may not prevent a person from developing the disease again. Individuals being treated for an STD are encouraged to abstain from all sexual activity until treatment is complete. Abstinence is necessary during this period to prevent reinfection.

Prevention of sexually transmitted diseases

The only 100-percent effective way of preventing STDs is abstinence (not engaging in any form of sexual activity). For people who choose to participate in sexual activity, the risk can be lowered by using condoms and limiting their number of sexual partners. The risk is significantly lowered by having one sexual partner who does not have any other sexual partners and who does not have an STD.

Prevention methods for sexually transmitted diseases (STDs) include:

  • Correctly using a male latex or polyurethane condom with every act of vaginal intercourse, anal intercourse and oral sex (mouth-to-genital contact). Although male latex condoms are not 100 percent effective, they significantly reduce the risk of transmission. Female condoms offer some protection from STDs, but are not as effective as male latex condoms. Condoms do not provide protection against sores on areas not covered by the condom. Using a water-based lubricant with condoms will reduce breakage.
  • Refusing to have sex with someone who will not use a condom.
  • Washing the genitals with soap and water after sexual activity. This may help to eliminate parasites and bacteria that may have contacted the genitals.
  • Urinating after sexual activity. This may help to eliminate bacteria that may have entered the urethra.
  • Performing regular genital self-examinations to become familiar with the normal appearance of the genitals. This knowledge will help to identify any symptoms that may develop if a person is exposed to an STD.
  • Abstaining from sex during a woman’s menstrual period. During menstruation, women who have HIV/AIDS are more infectious and women who do not have the disease are more likely to become infected. Using a condom during menstruation can reduce this risk.
  • Vaccinations for human papilloma virus (HPV) and the hepatitis B virus.
  • Avoiding anal intercourse. The rectum and anus contain a large amount of bacteria. Contact with these bacteria can cause STDs in both women and men. In addition, the mouth, vagina and penis should not be exposed to any object that has been in contact with an anus or rectum. If anal intercourse is preferred, a male latex condom should always be used.
  • Using caution when sharing sex toys. Because STDs can be transmitted through shared bodily fluids, individuals should use condoms with sex toys when appropriate.

People are encouraged to discuss their sexual history with their sexual partners and to ask their partners about their history. These discussions are important regardless of gender because people who engage in sexual activity of any kind are all at risk for STDs. Partners should also discuss drug habits, and whether testing for STDs is necessary. These screening tests can be conducted during routine medical checkups. Testing is particularly important at the beginning of a new sexual relationship.

Because a partner may be dishonest about their drug use, sexual history or the fact they have (or have not) been tested, people are encouraged to look for signs and symptoms of STDs on their partner. Although many STDs do not always have noticeable symptoms, people should never engage in sexual activity with a partner who is visibly showing symptoms of an STD. In addition, people are encouraged to abstain from engaging in sexual activity with a partner who is being treated for a curable STD. The disease may be transmitted at any time until the course of treatment is complete.

Questions for your doctor regarding STDs

Patients may wish to ask their doctor the following questions related to sexually transmitted diseases:

  • What STDs present the greatest risk to me?
  • How can I tell if I am infected with an STD?
  • How can I tell if my partner is infected with an STD?
  • How often should I be tested for STDs?
  • How will I be tested for STDs?
  • What are the treatment options for my condition?
  • What are the risks associated with the treatment?
  • When will I see improvement in my condition?
  • How long must I abstain from sexual relations?
  • What are the chances of an STD recurrence?
  • How will the STD affect my chances of getting pregnant?
  • What will be done to prevent complications during birth if I have an STD?