Stats About 3 million new cases are diagnosed each year, making it the most common sexually transmitted bacterial infection.
Symptoms Though 75 percent of affected women don't have symptoms, there may be painful or frequent urination, vaginal discharge, pelvic or abdominal pain during sex, sore throat, fever, or nausea.
Testing A culture of cervical cells, a urine sample, or a test that can detect the DNA of the chlamydia organism.
Risks Up to 40 percent of women with untreated chlamydia will develop pelvic inflammatory disease (PID) -- an infection of the uterus, fallopian tubes, and ovaries -- which can lead to infertility. The bacteria can cause miscarriage, preterm birth, and, if passed to the baby during delivery, infant pneumonia or eye infections.
Stats The CDC estimates that there are more than 700,000 cases of gonorrhea each year.
Symptoms Signs are the same as chlamydia, though half of infections don't cause symptoms.
Testing A culture of the cervix. (Get tested for both chlamydia and gonorrhea -- they often appear together.)
Risks Untreated, gonorrhea can cause joint pain, arthritis, affect the heart and brain, and lead to PID in 10 to 20 percent of affected women. It can also cause miscarriage and, if it infects a newborn's eyes, lead to blindness.
Treatment Antibiotics. Many states treat all newborns' eyes with silver nitrate drops to prevent infection.