Transmission

The transmission of a sexually transmitted disease happens in sexual intercourse, through the mucosa of the sexual organs and sometimes also of the mouth.

The risk of infection increases when body fluids like semen, vaginal fluid or blood are involved.

Here, sexual intercourse is understood to include petting without penetration, oral sex, anal sex and vaginal intercourse. 

However, an infection can not only happen when body fluids are exchanged but also when one touches skin lesions caused by a disease, like e. g. spots, warts or abscesses.  

The transmission happens through various germs, among which are bacteria, viruses and parasites. In former times, humans were completely helpless against many of these germs, but today this is fortunately not the case any more. There are effective therapies against this sort of diseases.