2nd Ebola case confirmed in Nigeria

Nigerian authorities on Monday confirmed a second case of Ebola in Africa's most populous country. The emergence of a second case raises serious concerns about the infection control practices in Nigeria, and also raise the spectre that more cases could emerge. It can take up to 21 days after exposure to the virus for symptoms to appear.

Nigerian authorities said a total of 70 people are under surveillance and that they hoped to have eight people in quarantine by the end of Monday in an isolation ward in Lagos. The emergence there is particularly worrisome because Lagos is the largest city in Africa with some 21 million people.

Nigeria is the fourth country to report Ebola cases and at least 728 other people have died in Guinea, Sierra Leone and Liberia.