Herpes simplex encephalitis (HSE) is caused by the same herpes simplex virus (HSV) that manifests in oral cold-sore or in genital sore. HSV encephalitis characteristically affects the temporal lobes of an infected individual's brain, while other encephalitides tend to be more diffuse. When the disease triggers brain inflammation, which occurs in 10% of cases of encephalitis (2 cases per million people), half of all untreated patients die (1 case per million people). Common symptoms include brain damage, partial paralysis, seizures, hallucinations and an altered state of consciousness. In rare cases a mother can pass HSE to her child at birth; symptoms then include lethargy, tremors, irritability, seizures and poor feeding in the first two weeks after birth.