Sexually transmitted infections are infections that we get from having unprotected sex with an infected person.
The cause of these infections can be a virus, a bacterium, or a parasite. There are at least 20 microbes that can enter the body through sexual contact and cause infection or disease. Some of these infections cause symptoms in the genital area or the body organ through which they have entered the body. For example, gonorrhea, through vaginal sex may cause female secretions , and in oral sex may cause sore throat.
Some germs enter the body through the genital tract but then move to other body organs and damage them, like HIV that attacks the immune system, or the hepatitis B virus that targets the liver. Among bacteria, gonorrhea and chlamydia; and among viruses, herpes, human papillomavirus warts , and hepatitis B are more common.
Mumps and lice are parasitic diseases that can be transmitted through sexual contact. HIV, which you will study in a separate series, is actually a sexually transmitted infection. In the appendix of this booklet you can get familiar with the characteristics of each of these diseases.
Not all infections that cause problems with the reproductive system are necessarily sexually transmitted. Women's yeast infections or urinary tract infections are diseases that may be seen in the genital tract but are not transmitted through sexual contact.