A parent asks the nurse to explain what causes encephalitis, because a child in the neighborhood has ...

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A Incorrect. Encephalitis is not caused by a specific type of fly often found in and near horse barns. Most infections are caused by viruses.
B Incorrect. Encephalitis can be caused by mosquitoes, but it is not the usual cause.
C Correct. Encephalitis can be caused by direct invasion of the CNS by a virus or postinfectious involvement of the CNS after a viral disease. After the neonatal period it is usually caused by a virus, most commonly herpes type I, herpes simplex, but can be caused by other organisms, such as bacteria, spirochetes, fungi, and protozoa.
D Incorrect. Cat scratch fever can cause encephalitis, but it is not the major cause. It usually follows the scratch or bite of a cat or kitten and is caused by bacteria.