Nigerian officials have confirmed five new cases of Ebola in Lagos and a second death from the disease.

Health minister Onyebuchi Chukwu says a nurse who treated the first Ebola fatality, Liberian-American Patrick Sawyer, has died after contracting the same virus.

The new cases raise concern the deadly virus will spread into Africa’s most populous nation. So far, the much smaller Liberia, Sierra Leone and Guinea have been the epicenter of the Ebola outbreak that has killed nearly 900 people this year.

This week, the World Bank pledged up to $200 million to help the three West African nations contain the outbreak, improve public health systems and help communities cope with the economic impact of the crisis.

Meanwhile, a second American aid worker who contracted Ebola in Liberia is said to be feeling somewhat better.

Nancy Writebol is being treated at Emory University Hospital in the city of Atlanta, Georgia, where she was taken after her medical evacuation flight from Liberia landed Tuesday.

Writebol contracted the deadly virus while working at a clinic in Monrovia, Liberia alongside American doctor Kent Brantly. Brantly also is being treated for Ebola at Emory and is said to be improving.

Both patients are in the same high security isolation ward.

There is no approved cure or vaccine for Ebola. But the two Americans have been given an experimental drug made from tobacco leaves.

•Source: VOA.