Stage 3 -- Recurrence: When people encounter certain stresses (also termed triggers), emotional or physical, the virus may reactivate and cause new sores and symptoms. The following factors may contribute to or trigger recurrence: stress, illness, ultraviolet light (UV rays including sunshine), fever, fatigue, hormonal changes (for example, menstruation), immune depression, and trauma to a site or a nerve region where previous HSV infection occurred.
Not every person with a herpes infection actually experiences breakouts of cold sores throughout his or her lifetime or even after initially becoming infected. How often someone has a herpes cold sore outbreak, how severe the outbreaks are, how contagious someone is after infection and how long the sores take to heal all depend on someone’s individual immune response.
A 2004 study in the New England Journal of Medicine found that suppressive therapy decreases the risk of HSV-2 transmission from symptomatic, infected partners to uninfected partners by 48%. So “the risk of transmission is significantly reduced, but cannot be eliminated even with suppressive therapy,” Johnston explains, and she stresses that the virus can be passed along even without signs or symptoms.