Microsoft cofounder Paul Allen is ramping up his commitment in the fight against Ebola. The billionaire philanthropist announced Thursday that he is pledging to donate "at least" 100 million dollars towards medical supplies, healthcare training and safe evacuation of humanitarian aid workers in West Africa, where -- according to a recent report from the World Health Organization -- the virus has now killed nearly 5-thousand people. Allen's pledge marks one of the largest private donations yet in the Ebola relief effort.