(i) Sexual contact transmission When having sex or similar sex with a person who has an STD, the pathogens of the STD enter the body through the broken mucous membrane and cause infection. According to the relevant studies, in heterosexual or same-sex sexual contact, the receiving party is more likely to be infected than the active party, so women are more likely to be infected with STDs than men. (B) indirect contact transmission Through contact with contaminated clothing, bath or share bathing utensils commode, some STDs can be transmitted through indirect channels, such as syphilis, gonorrhea, candida infection. （Human immunodeficiency virus, syphilis spirochete, hepatitis B virus, hepatitis C virus, etc. can exist in blood and blood products, AIDS, syphilis, hepatitis B, hepatitis C can be transmitted through blood transfusion and blood products. (D) Mother-to-child transmission In close contact with the fetus before birth, during birth and after birth, the sick mother can be transmitted to the fetus or newborn through the placenta, birth canal, breastfeeding, etc., such as HIV, syphilis spirochetes, herpes virus, etc., can be transmitted to the fetus through the placenta; gonococcus, Chlamydia trachomatis, mycoplasma, etc., can be transmitted to the newborn through the birth canal; HIV can be transmitted to the baby through breastfeeding. (E) Medical transmission If the instruments used in medical operations are not sterilized or are not sterilized properly, medical transmission can be caused through examination, injection, surgery, etc. Inadequate protection of doctors, nurses and epidemic prevention personnel, such as contamination of fingers with syphilis spirochetes during delivery; medical personnel mistakenly stabbing their own skin with HIV-contaminated needles or scalpels; caring for children with AIDS, etc., may cause occupational transmission.