Herpes Simplex Virus (HSV)
A highly contagious virus that causes lifelong herpes infection. HSV is categorized into two types — herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2). HSV-1 is mainly transmitted by oral-to-oral contact and causes oral herpes, which affects areas in or around the mouth. HSV-1 can also be transmitted through oral-to-genital contact (oral sex) and causes genital herpes, which affects the genital or anal area. HSV-2 is transmitted by genital-to-genital sexual contact and causes genital herpes. In people who are immunocompromised, including people with HIV, the symptoms of HSV can be more severe and recurrent outbreaks can be more frequent than in people with healthy immune systems. People who have both HIV and genital herpes are more likely to transmit HIV to a partner who does not have HIV during sexual contact.