The Ebola death rate has fallen even though there are no specific medicines or vaccines to fight the virus. In a letter published online Wednesday by the New England Journal of Medicine, Dr. Kathryn Jacobsen of George Mason University in Fairfax, Virginia, and other doctors tell of 581 patients taken to an Ebola treatment center that opened near Sierra Leone's capital, The new results are cause for "cautious optimism" that access to care may be improving survival, said one author of the earlier report, Tulane University's Dr.