The Ebola epidemic that has killed more than 1500 people across West Africa has spread to a fifth country in the region with the first confirmed case of the deadly virus in Senegal.
The case marks the first time a new country has been hit by the outbreak since July and comes a day after the World Health Organisation warned the number of infections is increasing rapidly.
Senegal's health ministry said the patient is a young Guinean man who was immediately quarantined on Friday at a Dakar hospital, where he is in a "satisfactory condition".
The man is believed to have been infected in Guinea's capital Conakry, and may have travelled to Senegal before Dakar closed its land border with Guinea on August 21.
Authorities are now scrabbling to piece together where he went and who he encountered, in a bid to halt the spread of the deadly virus.
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New figures released by the WHO on Thursday revealed the massive scale of the crisis, which it said indicated a "rapid increase still in the intensity of transmission".
The UN agency said the number of cases could exceed 20,000 before the epidemic is brought under control.
Never before has there been an Ebola outbreak so large, nor has the virus -- which was first detected in 1976 -- ever infected people in West Africa until now.
As of August 26, 1552 people had been confirmed dead from Ebola in four countries -- Sierra Leone, Liberia, Guinea and Nigeria.
Liberia was the worst affected with 694 deaths; 422 people have died in Sierra Leone; and 430 in Guinea, where the virus emerged at the start of the year. Nigeria has now recorded six deaths.
The Democratic Republic of Congo has also confirmed two cases of Ebola, but officials there insist it is unconnected to the current outbreak in West Africa.
Nigeria's latest death -- in the southeastern oil city of Port Harcourt -- was the first outside its biggest city, Lagos, and dashed hopes that the country had successfully contained the virus.
The victim, a doctor named Ikyke Samuel Enuemo, is believed to have caught the virus from a patient he treated who travelled to the city after coming into contact with an infected Liberian-American man.
Some 160 people are now under surveillance in Port Harcourt following the doctor's death, the local government said on Friday.
Scientists meanwhile said the first human trials of a potential vaccine will start next week using a product made by pharmaceuticals giant GlaxoSmithKline and the US government.
On Friday, scientists writing in the journal Nature said 18 lab monkeys given high doses of the Ebola virus fully recovered after being given the prototype drug ZMapp, which reversed bleeding in the animals.
ZMapp has been given to a handful of frontline health workers who have contracted Ebola, two of whom have recovered, and two of whom have died. Three others are still receiving the treatment.
