STDs And STIs Are Not One In The Same: Here’s The Major Difference - Page 2
What Causes STIs?

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STIs are usually transmitted through sexual contact, including the exchange of bodily fluids or skin contact via the penis, vagina, anus or mouth. Most STIs are either caused by bacteria, a virus or a parasite.
HIV and HPV are caused by a virus. Chlamydia and syphilis are caused by bacteria. Trichomonaisis is caused by a parasite known as Trichomonas vaginalis.