From the link about Bubonic Plague:
In septicemic plague there is bleeding into the skin and other organs, which creates black patches on the skin, hence the name ( The epidemic form of bubonic plague experienced during the Middle Ages when it killed nearly half the people of western Europe ) Black Death.
Untreated septicemic plague is universally fatal, but early treatment with antibiotics is effective ... reducing the mortality rate to around 15% (USA 1980s).
People who die from this form of plague often die on the same day that symptoms first appear.
With pneumonic plague infecting lungs came the possibility of person-to-person transmission through respiratory droplets. The incubation period for pneumonic plague is usually between two to four days,
but can be as little as a few hours.
The initial symptoms of headache, weakness, and coughing ... are indistinguishable from other respiratory illnesses.
Without diagnosis and (antibiotic) treatment the infection can be fatal in one to six days; mortality in untreated cases may be as high as 95%.
Now that is frightening, especially in light of the fact, quoting, "People who die from this form of plague often die on the same day that symptoms first appear."
So if people don't know they have the symptoms and don't go to the doctor for treatment despite that, there's a 95% chance they'll die untreated. Did I interpret that wrong?