causes of a recurring fever
There are two types of herpes simplex virus. Type 1 usually causes oral herpes, or fever blisters. Type 2 usually causes genital herpes. Although both type 1 and type 2 viruses can infect oral tissues, more than 95 percent of recurrent fever blister outbreaks are caused by the type 1 virus. Herpes simplex virus is highly contagious when fever blisters are present, and the virus frequently is spread by kissing.