Sexually Transmitted Infections are diseases that are passed on from one person to another through sexual contact. The infection can be passed on via vaginal intercourse, oral sex, and anal sex. Some sexually transmitted infections can spread through the use of unsterilized IV drug needles, from mother to baby during childbirth or breastfeeding, and blood transfusions. Sexually transmitted infections have been around for thousands of years. Microorganisms that exist on the skin or mucus membranes of the male or female genital area can be transmitted, as can organisms in semen, vaginal secretions or blood during sexual intercourse. The genital areas are generally moist and warm environments - ideal for the proliferation of yeasts, viruses and bacteria. Sexually transmitted infections are more easily passed on during unprotected sex.