The document outlines symptoms of viral encephalitis, ranging from mild flu-like symptoms such as headache, fever, muscle aches, and fatigue in most cases, to more severe symptoms requiring prompt medical care such as severe headache, fever, altered consciousness, confusion, seizures, muscle weakness, and hallucinations. Symptoms in infants and young children may additionally include bulging fontanels, nausea, vomiting, body stiffness, inconsolable crying worsening with movement, and poor feeding.