It was very common that the Spanish Flu would kill people in less that 24 hours.
You need to read up on cytokine storm...and how some viruses are so viral; that they can turn the human body into a killing machine...literally cause the lungs to hemorrage within hours.
http://en.wikipedia.org/wiki/Cytokine_storm
Other interesting read is the book by Barry, “The Great Influenza”
Thank you all for the information. I have learned something new today. (My goal for everyday that the Lord allows me to wake up in the morning.)