Nigerian authorities say they have confirmed a second case of Ebola in Africa's most populous country. Nigerian Health Minister Onyebuchi Chukwu said Monday that the second person with Ebola is a doctor who had helped treat Patrick Sawyer, the Liberian-American man who died of Ebola in late July, AP reported. Sawyer, who was traveling to Nigeria on business, became ill while aboard a flight and Nigerian authorities immediately took him into isolation. Nigeria is the fourth country to report Ebola cases and at least 728 other people have died in Guinea, Sierra Leone and Liberia.