Blue Plague

I am thinking about the BP... I think the infected might not have symptoms right away, and that would have helped it's spread, so the victim feels fine but is contagious thus spreading the illness, by the time the first blue welts appear the chance of curing the victim is low, &amp; tons of people have been exposed.<div><br /></div><div>Is 90% mortality rate to high?</div><div><br /></div><div><br /></div>