simplex

It’s been associated with infections such as the herpes simplex virus and Epstein-Barr virus, as well as Lyme disease and autoimmune disorders.

The herpes simplex virus is very common and up to 80 percent of Swedish adults may be infected.

The viruses—usually benign varieties such as the herpes simplex viruses and adenoviruses that are often modified to make them safer and more potent—can reproduce in tumor cells but not in healthy cells.

They didn’t have herpes simplex infection, a dangerous but treatable cause of encephalitis, or HIV, which can cause similar symptoms.

Deaths caused by HSV-1 - herpes simplex 1 - are almost unheard of in healthy people.