DALLAS — A second Dallas hospital worker who provided care for the first Ebola patient diagnosed in the U.S. has tested positive for the disease, and officials on Wednesday began reaching out to passengers who had been on a flight with her the day before she fell ill. It's not clear how the worker contracted the virus, though the second case among health workers pointed to lapses beyond how one individual may have donned and removed personal protective garb. Authorities declined to say what position she holds at Texas Health Presbyterian Hospital or the type of care she provided to Thomas Eric Duncan, who was diagnosed with Ebola after coming to the U.S. from Liberia.