Sexually transmitted diseases (STDs)
STDs are diseases that can be transmitted through body contact during intercourse. They can be easily passed to the sexual partners, and some STDs can also be passed from a mother to her unborn child. STDs are caused by viruses, bacteria or parasites. There are at least 25 different sexually transmitted diseases. The common ones are chlamydia, herpes, HIV, gonorrhea and syphilis. Many STDs are infectious and can cause long-term or permanent damage, including infertility if left untreated.