As well as four deaths, Nigeria yesterday confirmed six others were being treated at a special isolation unit in its economic capital of Lagos, correcting earlier reports that 11 people had been infected.
A serious outbreak in Lagos, Africa's most populous city, could severely disrupt the oil and gas industry in Nigeria if international companies are forced to evacuate staff and local operations are shut down, the Moody's rating agency warned on yesterday.
Any "decline in production would quickly translate into economic and fiscal deterioration," said Matt Robinson, senior credit officer at Moody's.
Meanwhile, US President Barack Obama called the President Ellen Johnson Sirleaf of Liberia and Sierra Leone's leader Ernest Bai Koromo, two of the countries worst hit by the epidemic which has claimed over 1,000 lives.
The calls came as the US State Department ordered families of its diplomats in Sierra Leone to leave the country to avoid exposure.
"In his conversations with both leaders, the president underscored the commitment of the United States to work with Liberia, Sierra Leone, and other international partners to contain the outbreak and expressed his condolences for the lives lost," the White House said in a statement.
In Sierra Leone's parliament yesterday, the country's chief medical officer, Dr Brima Kargbo, spoke of the difficulties health workers were facing in fighting the epidemic.
"We still have to break the chain of transmission to separate the infected from the uninfected," Kargbo said. But, he added: "There is a rejection among people of the existence of Ebola and hostility towards health workers."
The disease has taken its toll on those trying to help its victims.
Sierra Leone yesterday disclosed that 32 nurses died from the Ebola virus while performing their duties between May 24 to August 13.
South Africa has stepped in to help the country by sending a mobile laboratory to be installed in the capital Freetown to ease the problem of having to send blood samples elsewhere for analysis, Sierra Leone's health ministry said.