An
infection of the
membranes that surround the
brain and/or
spinal cord.
My unfortunate recent experience with meningitis manifested itself as an unrelenting headache only mildly affected my any kind of painkilling medication which I tried to apply. Because it was viral, and not bacterial, there was nothing to be done. Bacterial meningitis can be treated by antibiotics, but obviously viruses are unaffected.
I was significantly worried when my friends used words like "survival rate" when referring to the disease, but as it turns out, viral meningitis is not very serious; it's more or less a two-week-long headache.
Bacterial meningitis, however, is much more severe, and should be treated with great speed. Otherwise, serious neurological damage could result.