A child with a fever and headache does not necessarily have encephalitis. Because fevers often cause headaches, some of the signs of encephalitis may be present. Because children with encephalitis may have headaches, confusion, changes in muscle tone, and mental delirium, encephalitis should not be considered as a cause of fever and headache. If the general condition is good, encephalitis is less likely. A distinction should be made between younger children and older children; children should not be considered to have encephalitis unless they have recurrent high fevers that do not go away. If an infant presents with a fever, a lumbar puncture is routinely performed to test the cerebrospinal fluid and assess whether it is encephalitis. Older children with well-developed brain barriers are less prone to encephalitis and should be evaluated on the basis of other clinical signs, such as irritability, vomiting, crying and restlessness. Often, fever and headache are not immediately associated with encephalitis, but rather with simple respiratory or gastrointestinal infections.