Chlamydia (also known as non-gonococccal urethritis) and Gonorrhea are common bacterial STIs. I am going to group them together because they are spread the same way and have similar symptoms and treatments.
These bacteria infect the reproductive organs of men and women. Often there are no symptoms. If symptoms do occur they may include pain with urinating, discharge or pelvic pain. Even if there are no symptoms these bacteria can damage a woman's fallopian tubes and cause infertility. You can not tell whether someone has chlamydia or gonorrhea by looking at them or smelling them.
Infections of the throat are possible from oral sex and cause a sore throat. This is much more likely when a man comes in someone's mouth. Giving oral sex to women is lower risk because the bacteria are typically found near the cervix rather than on the vulva.
Gonorrhea can also cause painful joint infections or meningitis (infection around the spinal cord) or infection of the heart valves. These conditions are rare.
These infections are spread by semen or vaginal fluids, so condoms are effective in preventing the spread.
Incidence:
In the US in 2011 there were over 1.4 million cases of chlamydia and 322,000 cases of gonorrhea.
Testing:
The most accurate test is a swab of the cervix or male urethra (tube urine comes out of). This is easily done during a routine yearly pap smear. A urine test is also available, but less accurate particularly for women.
If you have had sex with someone with Chlamydia or Gonorrhea you should be tested.
Women who have more than one partner should be tested yearly. Men who have sex with men should be tested yearly.
Treatment:
Currently both these infections can be cured with medication.
Chlamydia is treated by one dose of an oral antibiotic.
Gonorrhea is treated with an antibiotic injection and an oral antibiotic. Drug resistant gonorrhea (infection that can not be cured with any antibiotic) is a growing problem around the world. Currently there has been one reported case in the US. Testing and proper treatment are important to help limit the spread of drug resistant bacteria.
If you have chlamydia or gonorrhea it is very important to inform your partners so they can be tested and treated. You can be reinfected after you are treated if you are exposed to the bacteria again.
Prevention:
Condoms have been shown to be effective in preventing the spread of chlamydia and gonorrhea.
Gonorrhea and Chlamydia resources:
http://www.cdc.gov/std/gonorrhea/stdfact-gonorrhea.htm
http://www.cdc.gov/std/chlamydia/stdfact-chlamydia.htm
Interesting article on drug-resistant gonorrhea:
