Hi, I'm sorry to hear of this tragedy.
1. The cause that first comes to mind is pneumonia. The worst cancers can kill in months, but pneumonia can kill in days.
2. Her high WBC count might have been a "leukemoid reaction". Leukemia can give a high WBC count, but won't kill so quickly. A leukemoid reaction gives high WBC counts just as with cancer, but actually comes from infection/inflammation instead.
3. Yes, leukemia means that the WBCs are multiplying out of control.
4. If it was pneumonia. then quick onset of death usually only occurs in infants or elderly - or in people who have a weakened immune system. Pneumonia caused by bacteria is more angers than pneumonia caused by a virus, but oftentimes a virus can pave the way foe the bacteria to thrive. However, a bacterial pneumonia usually comes with a fever.
There was a famous man named Jim Hensen (who created the Muppets) who died from a bacterial pneumonia. His doctors didn't diagnose it at the beginning because he didn't have the expected fever. The bacteria then got out of control and spread to all his organs.
If not pneumonia, then maybe some much more rare cause was involved. Whatever caused the high WBCs also caused the death, but having high WBCs doesn't cause a quick death in itself.
If she had a "differential" to show which of the WBCs were high (lymphocytes or neutrophils or some other cell) then that would help to diagnose the cause.
Thanks for answer
Different test reports shows following
Neutrophils 82%
Lymphocytes 14%
Monocytes 0%
Eosinophils 4%
Basophils 0%
Serum creatinine 1.52
Alkaline phosphatase 348.62
Bilirubin Uncojucated 0.51
The high number of neutrophils would fit with a bacterial infection. Or a fungus infection, but a systemic fungus infection would be less common.
The creatinine is high, she might have been dehydrated because of being so sick.
Sepsis could have caused high levels of alkaline phosphatase, and also increased creatinine. Infection causes rapid pulse rate, too.
The unconjugated bilirubin is apparently at the low end of normal, it might have gotten much higher while she was being transported.
All of this is just guesswork on my part. But the possibilities from sepsis are all potentially fatal: Acute Respiratory Distress Syndrome (ARDS), septic shock, organ failure. Such a terrible tragedy.
You might want to look at this account:
http://articles.latimes.com/1990-05-21/news/vw-267_1_viral-pneumonia
"Pneumonia: A Deadly Presence"