Herpes simplex encephalitis
Herpes simplex encephalitis (HSE), or simply herpes encephalitis, is a rare form of encephalitis caused by the herpes simplex virus. It is estimated to affect at least 1 in 500,000 individuals per year, and some studies suggest an incidence rate of 5.9 cases per 100,000 live births.
Source: Wikipedia — Herpes simplex encephalitis (CC BY-SA 4.0)