A health worker is sprayed with disinfectant after he worked with patients that contracted the Ebola virus, at a clinic  in Monrovia, Liberia, Monday, Sept. 8, 2014.  Border closures, flight bans and mass quarantines are creating a sense of siege in the West African countries affected by Ebola, officials at an emergency African Union meeting said Monday, as Senegal agreed to allow humanitarian aid pass through its closed borders. (AP Photo/Abbas Dulleh)

CDC chief drops worst-case Ebola estimate

In September, the Centers for Disease Control and Prevention estimated the number of people with Ebola could explode to as many as 1.4 milli…