Cоrа, а 41-yeаr-оld lawyer and mоther of two, has recently been experiencing severe headaches, a high fever, and a stiff neck. The doctor suspects that Cora may have meningitis, a potentially life-threatening infection of the tissue that surrounds the brain and spinal cord. Meningitis has several potential causes. It can be brought on by bacteria, fungi, or viruses. Bacteria or fungi were not isolated from Cora’s CSF sample, so her doctor rules out bacterial and fungal meningitis. What type of microbe could be causing Cora’s symptoms?