Aid worker Nancy Writebol becomes second American infected . Dr. Kent Brantly is ill after treating Ebola patients in Liberia last week . The U.S. Centers for Disease Control and Prevention said Thursday that the first case of a person who contracted Ebola outside West Africa has been diagnosed in Texas. A doctor working on the Ebola outbreak in Sierra Leone is also infected .
Aid worker Nancy Writebol becomes second American infected . Dr. Kent Brantly is ill after treating Ebola patients in Liberia last week . The current outbreak of Ebola virus is the deadliest ever , health officials say . A doctor working on the Ebola outbreak in Sierra Leone is also infected .