Diseases and Conditions
Sexually transmitted diseases (STDs)
Overview
Symptoms
Causes
Risk factors
Complications
Prevention
Diagnosis
Treatment
Coping and support
Preparing for an appointment
Causes
STDs or STIs can be caused by:
- Bacteria. Gonorrhea, syphilis and chlamydia are examples of STIs that are caused by bacteria.
- Parasites. Trichomoniasis is an STI caused by a parasite.
- Viruses. STIs causes by viruses include HPV, genital herpes and HIV.
Other kinds of infections — hepatitis A, B and C viruses, shigella infection and giardia infection — can be spread through sexual activity, but it's possible to be infected without sexual contact.
