Home > Encyclopedia of Science > Sexually Transmitted Diseases

• Bacterial STDs
• Words to Know
• Viral STDs
• Other STDs
• Prevention

Long known as venereal disease, after Venus, the Roman goddess of love, sexually transmitted diseases (STDs) are among the most common infectious diseases in the world. (An infectious disease is one caused by a parasite that attacks a host and begins to multiply, interfering with the normal life functions of the host.) There are more than 20 known STDs, ranging from life-threatening to painful and unsightly.

While acquired immunodeficiency syndrome (AIDS) is the most widely publicized STD, others are more common. Chlamydia, gonorrhea, and genital warts are nearing epidemic rates in the United States. Other common STDs include genital herpes, trichomoniasis, and chancroid (pronounced...