Herpesviral encephalitis also referred to as herpes simplex encephalitis (HSE) is caused due to herpes simplex viral infection. Individuals with HSE show a decrease in their level of consciousness and confusion, and changes in personality. Patient's cerebrospinal fluid contains ncreased numbers of white blood cells without the presence of pathogenic bacteria and fungi. Patients usually have a fever and seizures. Diagnosis involves testing of the cerebrospinal fluid (CSF) by a lumbar puncture (spinal tap) for presence of the virus