The most common cause of sporadic viral encephalitis is:

Ans. is 'b' i.e., Herpes simplex encephalitis (Ref: David Greenwood, 18th/e, p. 424)* Encephalitis caused by HSV - 1 is a rare condition, but it is the most common cause of sporadic fatal encephalitis in developed countries (1 - 2 cases per million population annually).* The disease carries a high mortality rate, and those who survive often have residual neurologic defects. About half of patients with HSV encephalitis appear to have primary infections, and the rest appear to have recurrent infection.