The cause of herpes is an infection from a virus. This virus is known as the human herpes virus. The human herpes virus has eight different strains so eight different diseases are the cause of herpes.
Of the 8 types of human herpes virus, only type one and two are the cause of herpes. To clarify, by the cause of herpes, it is meant genital and oral herpes. Genital herpes typically occur from Human herpes virus 2 or herpes simplex virus 2. Oral herpes typically occurs from Human herpes virus 1 or herpes simplex virus 1.
In either location, these infections are characterized by recurrent eruptions of small, painful vesicles in these areas. These vesicles shed the human herpes virus and are very contagious. These are the source of herpes infections.
Once you are infected with the virus, you will always have it. However, it remains non-infectious for a majority of the time. The cause of herpes eruptions as described previously is due to a variety of reasons. Often eruptions occur when there is physical or emotional stress. Another cause of herpes eruptions is due to sunburns, other illnesses such as the flu. Unfortunately the cause of herpes outbreaks is not completely catalogued. Often an outbreak just happens and the infected person must simply be prepared to deal with it.
So, the cause of herpes itself is the Human herpes virus. There is no other cause that can be attributed to an outbreak. The cause of herpes outbreaks include unusual stresses, sunlight, fevers, and sometimes, nothing at all.