Acquired Immune Deficiency Syndrome (AIDS)
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 and to certain forms of cancer. Transmission of the virus occurs during sexual activity or by the sharing of needles used to inject intravenous drugs.

Human Papillomaviruses (HPVs)
Human papillomavirus (HPV) is a common sexually transmitted disease that can cause genital warts called condylomas. These condylomas can occur on the inside or outside areas of the genitals and may spread to the surrounding skin or to a sexual partner. Because HPV infection does not always cause warts, the infection may go undetected. Women with HPV infection have an increased risk of developing cervical cancer. Regular Pap smears can detect HPV infection as well as abnormal cervical cells.

Although there is treatment for the condylomas (which sometimes go away on their own), the virus remains and warts can reappear. Smoking appears to increase problems related to HPV infection. Other types of HPV can also cause warts on other body parts such as the hands, called common warts, however, these do not generally cause health problems.

Chlamydial Infections
Chlamydial infections, the most common of all STDs, can affect both males and females. Infections may cause an abnormal genital discharge and burning with urination. In females, untreated chlamydial infection may lead to pelvic inflammatory disease (PID). However, many people with chlamydial infection have few or no symptoms of infection.

Gonorrhea
Gonorrhea causes a discharge from the vagina or penis and painful or difficult urination. The most common and serious complications occur in females, which include pelvic inflammatory disease, ectopic (tubal) pregnancy and infertility.

Genital Herpes
Genital herpes infections are caused by the herpes simplex virus (HSV).

Symptoms may include painful blisters or open sores in the genital area, which may be preceded by a tingling or burning sensation in the legs, buttocks, or genital region. The herpes sores usually disappear within a few weeks, but the virus remains in the body and the lesions may recur from time to time.

Syphilis
The initial symptom of syphilis is a painless open sore that usually appears on the penis or around or in the vagina. If untreated, syphilis may go on to more advanced stages, including a transient rash and, eventually, serious involvement of the heart and central nervous system.

Genital Warts
Genital warts or venereal warts (condylomata acuminata) are caused by a virus related to the virus that causes common skin warts. Usually, genital warts first appear as small, hard, painless bumps in the vaginal area, on the penis, or around the anus.

Other diseases that may be sexually transmitted include the following:

• Bacterial vaginosis.

• Chancroid.

• Cytomegalovirus infections.

• Granuloma inguinale (donovanosis).

• Lymphogranuloma venereum.

• Molluscum contagiosum.

• Pubic lice.

• Scabies.

• Trichomoniasis.

• Vaginal yeast infections.

Source: National Institute of Allergy
and Infectious Diseases