Background: Along with vitamin D, smoking, body mass index and others, Epstein Barr virus, other herpesviruses
and human endogenous retroviruses represent plausible environmental risk factors for multiple sclerosis. However,
it is difficult to obtain direct proof of their involvement in the etiology of this condition.
Case presentation: In order to contribute further evidence of the importance of these viruses, and speculate about
disease-relevant interactions between these agents and a predisposed genetic background of the host, we describe
the temporal association between multiple sclerosis onset and Herpes simplex 1-encephalitis in a female patient.
Conclusions: This case illustrates a possible relationship between HSV-1 encephalitis and multiple sclerosis. Bearing
in mind that association does not imply causation, some speculations about the etiology and pathophysiology of
the two diseases can be made. The hypothesis of a genetic background predisposing to HSV-1 encephalitis and to
immune-mediated demyelination is supported by the coincidence of the two conditions in this patient, along with
data from animal models and genetic studies
