[Polybius]

5 to 10% is not a very focused number either though.

That depends on how serious the consequences of the disease could be.

In the 1920s, 77 of 78 children at Boston Children's Hospital who had Haemophilus influenzae meningitis died. The prognosis for untreated pneumococcal meningitis was equally bleak: of 300 patients, all died. In the first decade of the 20th century, untreated meningococcal meningitis was associated with a mortality rate of 75 to 80 percent.

[GovernmentShrinker]

Meningitis can move with frightening speed. A friend of mine had a sister die of meningococcal meningitis. The sister was at college, a couple of hours from home. First she thought she just had a cold, but it got worse so the next day she went to the college clinic. The clinic transferred her to a hospital immediately, thinking she had the flu but concerned that it was a bad case, since she had a high fever. The clinic called the parents right away to notify them that their daughter had been admitted to the hospital with flu symptoms. The parents jumped in their car and took off for the hospital. Their daughter was already dead by the time they got there.