The Centers for Disease Control and Prevention is rethinking its recommended protocols for preventing the spread of Ebola after a Dallas nurse contracted the disease. The nurse has been identified as 26-year-old Nina Pham. It is still unclear how she became infected while wearing a mask and other protective gear as she treated Thomas Eric Duncan, who died of Ebola last week. The CDC has identified what it calls a “large group” of other workers involved in Duncan’s care who may be at risk.