For some parents, Tuesday's report that found one in four teen girls has a sexually transmitted disease is simply unbelievable.

But doctors say the stunning statistics match patients' charts.

"If you went out on the street, you'd find parents who would say, 'not my child,'" said Emory University gynecologist Kevin Ault. "But this is close to the truth, whether we like it or not."

The Centers for Disease Control study released this week also found about half of girls ages 14 to 19 said they've had sex.

Ault said the findings should encourage parents to take an active role in protecting their daughters' reproductive health — talk to your kids, make sure they get screened and consider vaccination against HPV.

"The numbers are really staggering and I think this really makes people notice," said Leola Reis, vice president of Planned Parenthood of Georgia. "Young people really need to hear from their parents about waiting and being safe."

Here's a look at the four most common STDs among teenagers, according to the CDC.:

Genital human papilloma virus (HPV)

• What is it? The most common sexually transmitted infection. Infects skin and mucous membranes. There are more than 40 HPV types that can infect the genital areas of men and women.

• Symptoms: Most with HPV do not develop symptoms or health problems. Certain types of HPV can cause genital warts and cervical cancer.

• Treatment: There is no treatment for the virus itself, but a healthy immune system can usually fight off HPV naturally. A vaccine is also now available for teenage girls to prevent HPV.

Chlamydia

• What is it: A common STD caused by the bacterium chlamydia trachomatis, which can damage a woman's reproductive organs.

• Symptoms: Even though symptoms of chlamydia are usually mild or absent, serious complications that cause irreversible damage, including infertility, can occur "silently" before a woman ever recognizes a problem.

Women infected with chlamydia are up to five times more likely to become infected with HIV, if exposed.

• Treatment: Easily treated with antibiotics.

Trichomoniasis

• What is it: Trichomoniasis is sexually transmitted parasite.

• Symptoms: Some women have signs or symptoms of infection, which include itching and a frothy, yellow-green vaginal discharge with a strong odor.

• Treatment: Antibiotics.

Genital Herpes

• What is it? Genital herpes is an STD caused by the herpes simplex viruses type 1 or type 2.

• Symptoms: One or more blisters on or around the genitals or rectum.

• Treatment: Herpes is incurable and there is no treatment.

Source: CDC