In March, Guinea's Ministry of Health notified the World Health Organization of an Ebola virus outbreak in the southeastern part of the country. The virus has rapidly spread.

Sierra Leone officials appealed for help on Friday to trace the first known resident in the capital with Ebola whose family forcibly removed her from a Freetown hospital after testing positive for the deadly disease.

Radio stations in Freetown, a city of around 1 million inhabitants, broadcast the appeal on Friday to locate a woman who tested positive for the disease that has killed 660 people across Guinea, Liberia and Sierra Leone since an outbreak was first identified in February.

"Saudatu Koroma of 25 Old Railway Line, Brima Lane, Wellington," the announcement said. "She is a positive case and her being out there is a risk to all. We need the public to help us locate her." 

Koroma, 32, a resident of the densely populated Wellington neighborhood, had been admitted to an isolation ward while blood samples were tested for the virus, Health ministry spokesman Sidi Yahya Tunis. The results came back on Thursday.

"The family of the patient stormed the hospital and forcefully removed her and took her away," Tunis said. "We are searching for her."

Fighting one of the world's deadliest diseases is straining the region's weak health systems, while a lack of information and suspicion of medical staff has led many to shun treatment.

The head doctor fighting Ebola in Sierra Leone has himself caught the disease.

The 39-year-old Sheik Umar Khan, hailed as a "national hero" by the health ministry, was leading the fight to control an outbreak that has killed at least 206 people in the West African country until he himself was infected. 

A Liberian man suspected to have Ebola has died in quarantine in Lagos, Nigeria, a Nigerian official in Geneva said Friday.

The man, who collapsed on arrival at the airport in Nigeria's commercial center on Thursday, was being kept in isolation by authorities and had not entered the mega-city of 21 million people, he said.

"While he was in quarantine he passed away," the official said.

DOZENS UNACCOUNTED FOR

Earlier this year, a man in Freetown tested positive for Ebola although he is believed to have caught it elsewhere.

According to health ministry data and officials, dozens of people confirmed by laboratory tests to have Ebola are now unaccounted for in Sierra Leone, where the majority of cases have been recorded in the country's east. 

While international medical organizations have deployed experts to the field in an attempt to contain the outbreak, the World Health Organisation (WHO) said poor health infrastructure and a lack of manpower were hindering their efforts.

"We're seeing many of these facilities simply don't have enough people to provide the constant level of care needed," WHO spokesman Paul Garwood told a news briefing in Geneva on Friday.

There is no cure or vaccine for Ebola, which causes diarrhea, vomiting and internal and external bleeding. It can kill up to 90 percent of those infected, although the mortality rate of the current outbreak is around 60 percent.  

The West African outbreak is the first time that Ebola, which was first discovered in what is now Democratic Republic of Congo in 1976, has appeared in heavily populated urban areas and international travel hubs.

Cases have already been confirmed in Conakry and Monrovia, the capital cities of Guinea and Liberia.

On Thursday authorities in Nigeria announced that they were testing a Liberian man for Ebola after he collapsed upon arrival at an airport in Lagos, the country's commercial capital and a mega-city of 21 million people.

NIGERIA CONFIRMS EBOLA CASE IN MEGACITY LAGOS

A Liberian man who died in Nigeria's commercial capital Lagos on Friday tested positive for the deadly Ebola virus, Health Minister Onyebuchi Chukwu said.

Patrick Sawyer, a consultant for the Liberian finance ministry in his 40s, collapsed on Sunday after flying into Lagos, a city of 21 million people, and was taken from the airport and put in isolation in a local hospital. Nigeria confirmed earlier on Friday that he had died in quarantine.

"His blood sample was taken to the advance laboratory at the Lagos university teaching hospital, which confirmed the diagnosis of the Ebola virus disease in the patient," Chukwu told a press conference on Friday. "This result was corroborated by other laboratories outside Nigeria." 

However, at a separate press conference held by the Lagos state government at the same time, the city's health commissioner, Jide Idris, said that they were only "assuming that it was Ebola" because they were "waiting for a confirmative test to double check" from a laboratory in Dakar.

Paul Garwood, spokesman for the World Health Organization (WHO) in Geneva, said the U.N. health agency was also still waiting for test results.

"We're still waiting for laboratory-confirmed results as to whether he died of Ebola or not," he said.

It could not be immediately determined why there was a contradiction in the comments from central government and city officials.

If confirmed, the man would be the first case on record of one of the world's deadliest diseases in Nigeria, Africa's biggest economy and with 170 million people, its most populous country. Ebola has killed 660 people across Guinea, Liberia and Sierra Leone since it was first diagnosed in February. 

Sawyer was quarantined on arrival and had not entered the city, a Nigerian official told Reuters.

"While he was quarantined he passed away. Everyone who has had contact with him has been quarantined," the official said. 

Liberia's finance minister Amara Konneh said Sawyer was a consultant for the country's finance ministry.

"Our understanding is that the cause of death was Ebola," Konneh told Reuters. 

The victim's sister had died of the virus three weeks previously, and the degree of contact between the two was being investigated by Liberian health ministry officials, he said.

Earlier on Friday, WHO spokesman Paul Garwood said: "I understand that he was vomiting and he then turned himself over basically, he made it known that he wasn't feeling well. Nigerian health authorities took him and put him in isolation."

Nigeria has some of the continent's least adequate healthcare infrastructure, despite access to billions of dollars of oil money as Africa's biggest producer of crude.

Some officials think the disease is easier to contain in cities than in remote rural areas. 

"The fear of spread within a dense population would be offset by better healthcare and a willingness to use it, easier contact tracing and, I assume for an urban population, less risky funerary and family rites," Ian Jones, a professor of virology at the University of Reading in Britain, said.

"It would be contained more easily than in rural populations." 

There have been 1,093 Ebola cases to date in West Africa's first outbreak, including the 660 who have died, according to the WHO.