Viral infections

This chapter looks at how enteroviruses are responsible for most cases of viral meningitis where a pathogen is identified; many other viruses can also cause meningitis with considerable geographical and seasonal variation. Their typical presentation is with sudden onset of fever, headache, neck stiffness, and photophobia. There is no change in conscious level. Prognosis is generally good, though recent data suggest not always. Viruses invade and damage the central nervous system in two ways: directly, by infecting the leptomeninges, brain, and spinal cord; and, indirectly, by inducing an immunological reaction resulting in para and postinfectious diseases. In both cases, the terms ‘meningitis’, ‘encephalitis’, and ‘myelitis’ are used alone or in combination.