The germs that cause disease can be found mainly in the blood, sperm, vaginal fluid and the mucous membranes of the penis, vagina and bowels of infected persons. For this reason, sexually transmitted diseases are transmitted primarily during vaginal sex (penis in the vagina), anal sex (penis in the bum) and oral sex (licking of vagina, penis or bum). 

But transmission is also possible from contact with sores, blisters or other cuts on infected people. You can also contract some sexually transmitted diseases through kissing. 

People who take drugs can become infected through syringes and needles that have been used by infected persons.

An infected person can infect their child during pregnancy, during birth or through breastfeeding.