Genital herpes is a genital infection caused by the herpes simplex virus (HSV). Most individuals carrying herpes are unaware they have been infected and many will never suffer an outbreak, which involves blisters similar to cold sores. While there is no cure for herpes, over time symptoms are increasingly mild and outbreaks are decreasingly frequent. When symptomatic, the typical manifestation of a primary infection is clusters of genital sores consisting of inflamed papules and vesicles on the outer surface of the genitals, resembling cold sores. These usually appear 4–7 days after sexual exposure to HSV for the first time. Genital HSV-1 infection recurs at rate of about one sixth of that of genital HSV-2. HSV has been classified into two distinct categories, HSV-1 and HSV-2. Although genital herpes was previously caused primarily by HSV-2, genital HSV-1 infections are increasing and now cause up to 80% of infections. In 2013 about 1.1 billion people (15.9%) had asymptomatic genital herpes and 47 million new cases of genital herpes occurred. A 1998 study indicated it was the most common sexually transmitted infection by the number of cases.