The source of a venereal disease transmission is an infected patient and their blood or secretion containing the pathogen. The ways of transmission can be classified as a sexually transmitted infection or a non-sexually transmitted infection.

1. Sexually transmitted infection:

Sexual behavior such as sexual intercourse, oral sex, anal sex, French kissing, etc. can all transmit venereal diseases, sexual intercourse is the main way. Over 95 percent of patients are infected in this way.

2. Non-sexually transmitted infection:

A healthy person with an open wound to their skin or a cut on the mucosa who directly touches the degenerative festered wound or the secretion of the patient can be infected.

2.1 Indirect contact: one can be infected with a venereal disease by touching the underwear, clothes, bedding, toilet, etc. contaminated by the patient.

2.2 Infection through blood: transmissible infection occurs if one transfuses blood from the patient who is infected with AIDS or syphilis. For example, by using the same injecting needle.

2.3 Placenta infection: when a pregnant woman is infected with a venereal disease, the pathogen will be transmitted to the infant through the placenta, for instance, congenital syphilis.

2.4 Birth canal infection: the pathogen can be transmitted to the infant through the birth canal during the process of giving birth.

2.5 Iatrogenic infection: during medical treatments, medical staff can be infected due to poor protection, such as when examining or operating on the patient, changing medicine for him/her, or due to a cut on their skin by the medical apparatus containing the pathogen, and carelessly sterilized medical apparatus.

2.6 Other ways: Artificial Insemination, organ transplants and tattoos can also cause these infections.