The World Health Organisation (WHO) is warning the Ebola outbreak in West Africa could infect more than 20,000 people.
It says the virus may spread to ten more countries beyond those already affected.
But the UN health agency is advising against travel bans and border closures.
“Bans on travel and trade and the rest will not stop this virus. Absolutely not. In fact, you are more likely to compromise the ability to respond, to get more and more disease, more and more people trying to move, you are going to get yourself in trouble,” said Bruce Aylward, a WHO official.
“It is a self-defeating strategy to ban travel, that’s not the problem.”
A doctor in Nigeria’s oil industry hub of Port Harcourt is said to be among the latest deaths. Seventy people are now being monitored in that area.
The WHO has announced a 380-million euro plan to contain the epidemic over the next nine months.
More than three-thousand cases of Ebola have so far been reported and over half of the victims have died.
In Britain, drug-maker GlaxoSmithKline is fast-tracking an experimental vaccine into human studies – in the hope that thousands of emergency doses could be deployed.