Diseases such as Chlamydia, human papillomavirus (HPV), gonorrhea, herpes, hepatitis (multiple strains), and other sexually transmitted diseases (STDs), as well as viruses such as HIV, can be transmitted through oral sex. The risk of transmitting HIV through fellatio is unknown, but it is thought to be low. Any kind of direct contact with body fluids of a person infected with HIV, the virus that causes AIDS, poses a risk of infection. The risk from most of these types of infection, however, is generally considered far lower than that associated with vaginal or anal sex.