Trichomoniasis is one of the most common sexually transmitted diseases, mainly affecting 16-to-35-year old females.

Syphilis has been called "the great imitator" because many of its signs look like other diseases. It is also difficult to know if someone has syphilis because a person might not have any symptoms at all.

This disease has bothered humans for thousands of years, but it seems to come and go in unexplainable cycles. Scabies used to be very rare in America, but now it is coming back again.

Pubic lice are often spread through sexual contact, though genital contact or sexual intercourse is not necessary for transmission. In a few cases, pubic lice have been spread through contact with bed linens, towels, or clothes because lice can live for 24 hours off a human body.

"Pelvic inflammatory disease" is shorthand for any serious bacterial infection of the reproductive organs that are housed in the pelvis: the uterus, uterine lining, fallopian tubes, and/or ovaries. These infections usually start in the vagina and, when left untreated, can progressively infect other reproductive organs. 20% of PID cases are found in teens, who often are afraid or unable to get reproductive health care. PID can result in permanent infertility and chronic pain.

As many as one in ten Americans have HPV, and some studies show that at least one-third of all sexually active young adults have genital HPV infections. It is often stated that more than half of all college-age women wil become infected with HPV during their college career.

HIV is a virus that destroys the immune system and thus weakens the body's ability to fight disease and infection, even common infections like flus and colds. HIV usually progresses to AIDS. This makes HIV the most dangerous sexually transmitted infection today. It is the fifth leading cause of death for the young under 40 in the United States. At this time, no one has been cured of HIV or AIDS.

About one in five people in the United States over age 12 -- approximately 45 million individuals -- are infected with HSV-II, the virus that causes genital herpes. Around 50 - 80% of the adult population has oral herpes, which most people contracted through casual contact in childhood.

In the United States, approximately 75% of all reported gonorrhea is found in people age 15 to 29.

Every year, CMV causes permanent disabilities, hearing loss and mental retardation for as many as 7,000 infants.

Chlamydia is the most common bacterial infection (STI) in the United States, with about 3 million new cases reported annually. Chlamydia ("cla-mid-ee-ah") is so common in young women that, by age 30, 50% of sexually active women have evidence that they have had chlamydia at some time during their lives.

Bacterial vaginosis (BV) is the most common cause of vaginitis symptoms among women of childbearing age (15-45). However, half the women who meet clinical criteria for BV have no symptoms.