Sexually transmitted diseases are caused by a variety of pathogens. These pathogens are present in the body of the patient and in certain secretions. Sexual intercourse is the main route of transmission of sexually transmitted diseases. When a healthy person has sexual intercourse with a patient, pathogens can invade the body through mild abrasions of the genital skin mucosa, such as gonorrhea and syphilis, or can be transmitted through close physical contact during sexual intercourse, such as scabies, infectious molluscum contagiosum and pubic lice.
Other sexual behaviors such as oral-genital contact, oral-anal contact, and genital-anal contact (anal sex) are among the transmission routes, such as AIDS and intestinal infections in gay men. The pathogens of a few sexually transmitted diseases can also be transmitted through indirect routes, such as gonorrhea, scabies and trichomoniasis transmitted through patient-contaminated towels, underwear, bedclothes, bath tubs and toilets. It can also be transmitted through blood transfusion or blood products, injection needles, etc., such as hepatitis and AIDS. Some sexually transmitted diseases can also be transmitted to the fetus or newborn during pregnancy and delivery, such as fetal syphilis, neonatal gonorrhea conjunctivitis, and neonatal herpes infection.
According to the route of transmission, STDs can be divided into the following types: Anal intercourse – sexual intercourse type (primary STD): mainly for anal intercourse transmission or sexual intercourse and transmission of diseases, represented by AIDS.
The STDs are mainly transmitted by intercourse or sexual intercourse, and are represented by gonorrhea, syphilis, soft chancre, lymphogranuloma venereum, inguinal granuloma, non-gonococcal urethritis, chlamydia/mycoplasma genitalium, trichomoniasis, etc.
Skin-mucosa-intercourse type (tertiary STD): mainly skin-to-skin, mucosa-to-mucosa contact transmission or inter-sexual contact transmission and diseases, such as condyloma acuminata,, candidiasis of the pubic area, genital herpes, pubic lice disease, scabies, infectious molluscum contagiosum, hepatitis B, herpes pubis, etc. as representatives.
Fecal-oral intercourse type (four-level intercourse) mainly for finger contamination fecal entrance and transmission or oral sex when fecal-oral transmission, such as intestinal Giardia infection, amoebiasis, shigellosis, salmonellosis, hepatitis A, etc. as representatives.