A noncompliant, human immunodeficiency virus (HIV)-positive patient has been complaining of a stiff neck and a severe headache. The headache was initially lessened by analgesics, but the analgesics are no longer effective. His current $DC4^+$ count is 180/mm3. He is not on any prophylactic drugs. What is the most likely causative agent?

Question

A noncompliant, human immunodeficiency virus (HIV)-positive patient has been complaining of a stiff neck and a severe headache. The headache was initially lessened by analgesics, but the analgesics are no longer effective. His current

DC4^+

count is 180/mm3. He is not on any prophylactic drugs. What is the most likely causative agent?