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Sexually Transmitted Infections (STIs)

Sexually transmitted infections (STIs) or sexually transmitted diseases (STDs) are infections primarily transmitted through sexual contact. They represent a significant public health burden, in part because of the stigma associated with STIs that prevents some patients from seeking treatment. When a patient is diagnosed with an STI, it is important for their partner to be tested and treated. Information on some of the most common STIs is listed in this brief review.

Sexually Transmitted Infections (STIs)

Chlamydia and Gonorrhea

Chlamydia is caused by the bacteria, Chlamydia trachomatis. Gonorrhea is caused by the bacteria, Neisseria gonorrhea. Women infected with either organism can develop symptoms of vaginal itching, burning, discharge or pain on urination. If left untreated, these infections can infect the female reproductive tract and lead to pelvic inflammatory disease (PID), which can cause infertility. Men may experience burning on urination and penile discharge. Women and men with Chlamydia or gonorrhea may not have any symptoms and not know they are infected until they are tested. These infections often occur together; a patient treated with antibiotics for either Chlamydia or gonorrhea may be treated for both.


Syphilis is caused by Treponema palladium, which is a corkscrew-shaped organism called a spirochete. Primary syphilis begins as a painless sore at the site of infection; this sore is called a chancre. If a patient with syphilis goes untreated, a few months after the initial infection he or she may develop symptoms of fever, fatigue, and rash. The rash of secondary syphilis varies in its appearance, but is often composed of red, pink, or brownish patches of skin that may be scaly and occur on the trunk, extremities, palms, and soles. A small number of untreated patients with secondary syphilis may develop tertiary syphilis, the last stage of the disease. Tertiary syphilis is characterized by involvement of the central nervous system (CNS) and cardiovascular system. Syphilis can be transmitted to babies during pregnancy. Syphilis is treated with antibiotics.

Sexually Transmitted Diseases (STDs)

Genital Warts (Condyloma)

Genital warts are caused by the human papilloma virus (HPV). They appear most commonly as small, soft, flesh-colored growths. They are usually asymptomatic, aside from their cosmetic appearance. The same virus that causes genital warts can cause cervical cancer in women; a PAP test is used to detect for the presence of cancerous cells of the cervix. Genital warts can be treated by chemical or surgical means, but may require repeated treatments.

Herpes Simplex Virus (HSV)

Genital herpes is caused by the human herpes simplex virus (HSV), types 1 and 2. HSV-2 is responsible for the majority of genital herpes cases. Herpes presents as a small fluid-filled vesicle that eventually erupts and becomes a painful shallow ulcer. After the initially outbreak, a person may have repeated outbreaks because the immune system does not entirely clear the HSV infection. The virus can be transmitted to infants if the mother has an outbreak during labor. Antiviral medication can be used to limit the duration and frequency of genital herpes outbreaks.

Crabs (Pubic Lice)

Crabs is an infestation of the hairy parts of the body, in particular the pubic area, with the crab louse, Pthirius pubis. It is transmitted by person-to-person contact; bedding is also a source of infection. Symptoms include itch and a rash composed of small red bumps. Pubic lice are treated with topical insecticides.

Human Immunodeficiency Virus (HIV)

Human immunodeficiency virus (HIV) is the virus that causes AIDS (acquired immunodeficiency syndrome). HIV infects cells vital to the function of the immune system, which is important in fighting off infection. Over time, a person with HIV becomes prone to infections that would normally be warded off with an intact immune system. HIV can be transmitted during pregnancy. There are effective treatments for HIV, but no cure or vaccine is currently available.


When used properly, condoms are effective in preventing transmission of STIs that are spread by contact with contaminated body fluid, such as semen, vaginal secretions, or blood. Condoms do not prevent the transmission of STIs in which the causative agent is present outside the protected skin, as may occur in genital warts, herpes, and pubic lice. Having one STI is often an indication for screening for other STIs. It is advisable to notify sexual partners of a recently diagnosed STI so that they may be tested and treated as well, thereby curbing the transmission of STIs to others.

Further information on STIs can be found at the website of the Centers for Disease Control and Prevention (CDC).