We know, for example, that gonorrhea was transmitted from cattle to humans. Syphilis also reached humans through cattle or sheep many centuries ago, possibly sexually. There were sheep native to the United States. But sheep have been in Asia, Africa and Europe for centuries before Columbus.
It is not realistic to think that a disease has occurred in all of Europe and Asia in only 30 or 40 people. But it does tell us much more about human history and can give us an idea of how exposure to disease has shaped human evolution. STDs have existed since the dawn of humanity. Herpes may have first infected our ancestors more than a million years ago.
Syphilis has existed since at least the Middle Ages. STDs may have encouraged humans to maintain monogamous partners. Soon, sexual health clinics were established to identify and treat people with sexually transmitted diseases and their partners, in order to prevent their spread among the general population. In the 20th century, the arrival of penicillin and other antibiotics led to an effective cure for bacterial STDs.
It was in the late 19th and early 20th centuries that the importance of tracing the sexual partners of a person infected with an STI was recognized. Before the arrival of modern medicine, people's lack of knowledge and understanding of STDs contributed to the widespread transmission of infections, while there were few or no treatments available to treat them. Sexually transmitted infections (STIs), also known as sexually transmitted diseases (STDs) and venereal diseases, referred to above, are infections that are transmitted through sexual activity, especially vaginal intercourse, anal sex and oral sex. Some STDs can have serious, life-changing consequences; syphilis, for example, can eventually cause progressive destruction of the brain and spinal cord, leading to mental dysfunction and hallucinations, speech problems and general paresis.
At the end of the 20th century, the transmission of viral sexually transmitted diseases such as HIV and herpes emerged, infections that are not curable and that in some cases can be fatal.