http://dermatology.about.com/library/blherptrigpoll.htm

Stress and anxiety seem to be the major triggers (menstruation, the
same story).

It is quite remarcable, isn't it?

About Poll  

What triggers a herpes outbreak for you?

Anxiety  (59)  
9%


Fatigue  (34)  
5%


Fever  (17)  
2%


Sun exposure  (50)  
7%


Heat  (18)  
2%


Cold  (26)  
4%


A break in the skin  (32)  
4%


Starting my period  (78)  
12%


Stress  (239)  
37%


Other  (92)  
14%


Total Votes: 645


http://jvi.asm.org/cgi/content/full/75/2/750?view=full&pmid=11134288

Virus infection induces an antiviral response that is predominantly
associated with the synthesis and secretion of soluble interferon.
Here, we report that herpes simplex virus type 1 virions induce an
interferon-independent antiviral state in human embryonic lung cells
that prevents plaquing of a variety of viruses. Microarray analysis of
19,000 human expressed sequence tags revealed induction of a limited
set of host genes, the majority of which are also induced by
interferon. Genes implicated in controlling the intracellular spread
of virus and eliminating virally infected cells were among those
induced. Induction of the cellular response occurred in the absence of
de novo cellular protein synthesis and required viral penetration. In
addition, this response was only seen when viral gene expression was
inhibited, suggesting that a newly synthesized viral protein(s) may
function as an inhibitor of this response.