Sexually Transmitted Diseases (STDs), or sexually transmitted infections (STIs), are infections that are passed from one person to another through sexual contact. The contact is usually vaginal, oral or anal sex.

What are the types of STIs?

Bacterial STDs include:

Chlamydia: Chlamydia is a common STD that can cause infection among both men and women. It can cause permanent damage to a woman's reproductive system. This can make it difficult or impossible to get pregnant later. Chlamydia can also cause a potentially fatal ectopic pregnancy (pregnancy that occurs outside the womb).

Gonorrhea: Gonorrhea is an infection caused by a sexually transmitted bacterium that infects both males and females. Gonorrhea most often affects the urethra, rectum or throat. In females, gonorrhea can also infect the cervix. Gonorrhea is most commonly spread during vaginal, oral or anal sex.

Gonorrhea is an infection caused by a sexually transmitted bacterium that infects both males and females. Gonorrhea most often affects the urethra, rectum or throat. In females, gonorrhea can also infect the cervix. Gonorrhea is most commonly spread during vaginal, oral or anal sex.

Syphilis: Syphilis is a bacterial infection usually spread by sexual contact. The disease starts as a painless sore — typically on the genitals, rectum or mouth. Syphilis spreads from person to person via skin or mucous membrane contact with these sores.

Viral STDs include:

HIV: HIV (human immunodeficiency virus) is a virus that attacks the body's immune system. If HIV is not treated, it can lead to AIDS (acquired immunodeficiency syndrome). Learning the basics about HIV can keep you healthy and prevent HIV transmission.

Genital Herpes: A common sexually transmitted infection marked by genital pain and sores. Caused by the herpes simplex virus, the disease can affect both men and women.

Genital Warts (HPV): A small bump on the genitals caused by a common sexually transmitted infection. Genital warts are a common sexually transmitted infection caused by the human papillomavirus (HPV). The characteristic symptom is a small bump on the genitals.

Hepatitis B: Hepatitis B is a vaccine-preventable liver infection caused by the hepatitis B virus (HBV). Hepatitis B is spread when blood, semen, or other body fluids from a person infected with the virus enters the body of someone who is not infected.

Can STIs be cured?

STIs are very common, and all STIs are treatable. Many are completely curable. Even STIs that are not curable can be treated and the symptoms managed with medicines. Effective treatment is currently available for several STIs. Three bacterial STIs (chlamydia, gonorrhea and syphilis) and one parasitic STI (trichomoniasis) are generally curable with existing single-dose regimens of antibiotics.