This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'Which of the folloing virus is the commonest cause of sporadic encephalitis? \nSelect and explain. \nA. Rubeola Virus, B. Japanese B Virus, C. Herpes Simplex Virus, D. Human Immunodeficiency Virus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Herpes simplex virus is the most common cause of sporadic fatal encephalitis. It mainly involves individuals more than 40 years of age. Primary HSV 1 often present as stomatitis and HSV type 2 manifest as venereally transmitted genital eruption. These virus then migrates along nerve axons to sensory ganglia, and persists in a latent form and may be reactivated later. In adults encephalitis is caused by HSV type 1. In neonates HSV encephalitis is caused by type 2 virus during passage through the bih canal of a mother with active genital lesions. HSV type 2 in adults causes meningitis, rather than encephalitis. Ref: Clinical Neurology By Roger P. Simon, 7th Edition, Chapter 1', 'role': 'assistant'}]