The spread of the disease comes as the World Health Organization (WHO) met in an emergency session in Geneva to decide whether to declare an international crisis.
The latest official toll across West Africa hit 932 deaths since the start of the year, it said Wednesday, with 1,711 confirmed cases, mostly in Guinea, Liberia and Sierra Leone.
The death of a nurse in Lagos, a megacity of more than 20 million people, came as 45 deaths were confirmed across West Africa between Saturday and Monday, with aid agencies, including Doctors Without Borders, saying the terrifying tropical disease is out of control.
In Liberia's capital Monrovia, where the dead have been left unburied on the streets or abandoned in their homes, President Ellen Johnson Sirleaf appealed for divine intervention and ordered three days of fasting and prayer.
And in Sierra Leone, which has the most confirmed infection cases, troops were sent to guard hospitals to "deter relatives and friends of Ebola patients from forcefully taking them from hospitals without medical consent," a presidential aide told AFP.
Returning Sierra Leonean troops serving with the African Union peacekeeping force in Somalia were ordered to remain in the war-torn country on Wednesday rather than risk returning home because of Ebola.
The closed-door WHO meeting was not expected to make a decision until Friday. But the session itself underscored the severity of the threat posed by the disease, which causes severe fever and unstoppable bleeding.
Meanwhile, a Spanish air force plane left for Liberia on Wednesday to bring an infected Spanish missionary priest home for treatment.
- Lagos outbreak raises stakes -
The outbreak in Nigeria remains minor compared with the other affected west African nations, but rising numbers in Lagos -- sub-Saharan Africa's most populous city -- pose unique challenges to health workers.
Nigeria's Health Minister Onyebuchi Chukwu said all seven confirmed cases in his country had "primary contact" with Patrick Sawyer, a Liberian finance ministry employee who brought the virus to Lagos on July 20.
Sawyer, who traveled to Nigeria from Monrovia via Togo's capital Lome for a regional meeting, was visibly sick upon arrival at the international airport in Lagos.
Officials said he was immediately transferred to a hospital next to the bustling Obalende market, where thousands of Nigerians shop for basic goods.
Sawyer died in quarantine on July 25 after infecting several hospital staff, including a nurse who died Tuesday night.
Chukwu had previously said that Nigeria was monitoring 70 people believed to have come into contact with Sawyer.
A Lagos state health official who requested anonymity said health workers were trying to track down all potential contacts of the six other patients, but he could not estimate how many people now needed to be monitored.
"There is no number yet," the official said.
- 'Learn lessons from AIDS' -
The new global head of the Red Cross warned on Wednesday that Ebola will be contained only if the public is won over, saying "stigma and discrimination often kill as much as viruses".
Elhadj As Sy said lessons had to be learned from the fight against AIDS and that dishing out blame does not help.
"It's very difficult in a west African cultural setting to tell people not to engage with their loved ones who are sick. But in this current situation they will have to do so," he said.
Religious burial rites that require relatives to wash the body of the dead make this particularly difficult, he said, since Ebola can spread from contact with dead bodies.
The Spanish victim in Liberia, Miguel Pajares, a 75-year-old Roman Catholic priest, had worked in the Saint Joseph Hospital in the capital Monrovia for seven years before falling sick with Ebola.
News that he would be evacuated on a specially equipped Spanish military Airbus A310 had lifted his "spirits", he told the online edition of daily Spanish newspaper ABC by telephone.
"I am very happy, it is worth fighting," he said.
Two Americans who worked for Christian aid agencies in Liberia were brought back to the United States for treatment in recent days.
Both patients were flown home on a private jet which had been fitted with a collapsible mobile isolation unit designed to transfer employees from the US Centers for Disease Control and Prevention exposed to contagious diseases.
British Airways said Tuesday that it had suspended flights to Liberia and Sierra Leone following concerns about the spread of the virus.
- Possible Saudi case -
A Saudi Arabian who had traveled to Sierra Leone and had Ebola-like symptoms died Wednesday of a heart attack, the health ministry said.
Officials did not disclose the results of the Ebola tests conducted abroad, but said he would be buried in an Islamic manner under precautions laid down by the world health authorities.
Aside from medical workers caring for those infected, people who bury Ebola victims are among the most at risk.
First discovered in 1976 and named after a river in what is now the Democratic Republic of Congo, Ebola spreads through contact with bodily fluids such as blood, saliva and sweat.
It has killed around two-thirds of those it has infected over the last four decades, with two outbreaks registering fatality rates approaching 90 percent. The latest outbreak has a fatality rate of around 55 percent.