The second American with Ebola virus is in Atlanta to be treated as health officials work to figure out just how she and a Texas doctor were infected. On Tuesday afternoon the U.S. Centers for Disease Control and Prevention says it's still working to complete its investigation. Closer to home, UTMB researchers are continuing to work on a potential medical breakthrough. An expert says he is encouraged by what he is seeing with the two American Ebola patients, but it is too soon to tell if they'll fully recover.