Herpes is a disease caused by the herpes simplex virus, or HSV (H-S-V). The virus is usually transmitted by direct contact with an infected individual, including kissing, oral sex, and sexual intercourse, or other situations in which viruses from the infection site contact broken skin or a mucous membrane like the mouth. HSV-type 1 most often results in 'fever blisters' or 'cold sores' around the mouth. HSV-type 2 typically causes lesions in the genital area. However, either virus can be spread to the opposite location. The number of herpes cases is on the rise, probably because the majority of those infected don't even know they have the disease. Most tests for sexually transmitted diseases don't look for herpes. In addition, symptoms may be so mild as to go unnoticed or may be absent entirely. The most common sign of infection is small, red blisters, which burst, scab over, and heal within a few weeks. A person may also develop flu-like symptoms such as fever, sore throat, swollen glands, and back aches. The first attack is generally the most severe; future recurrences tend to be milder and may occur four or five times a year. Often, a tingling or painful sensation appears before the actual lesions do. However, even if no further outbreaks are experienced, the herpes virus remains in the nervous system.