The pace of the infection has accelerated, and there were close to 400 deaths in the past week, officials said on Wednesday. It was first detected deep in the forests of southeastern Guinea in March.
The hemorrhagic fever has spread to Liberia, Sierra Leone, Guinea, Nigeria, and Senegal, and has killed more people than all outbreaks since Ebola was first uncovered in 1976. There are no approved Ebola vaccines or treatments.
An experimental Ebola vaccine that Canada said it would give to the World Health Organization for use in Africa was as of Wednesday still in the lab that developed it as officials are puzzled over how to transport it.
Ottawa said on Aug. 12 that it would donate between 800 and 1,000 doses of the vaccine, being held at Canada's National Microbiology Laboratory in Winnipeg.
"We are now working with the WHO to address complex regulatory, logistical and ethical issues so that the vaccine can be safely and ethically deployed as rapidly as possible," Health Canada spokesman Sean Upton said in a statement.
"For example, the logistics surrounding the safe delivery of the vaccine are complicated." Upton said one of the challenges was keeping the vaccine cool enough to remain potent.
Human safety trials are due to begin this week on a vaccine from GlaxoSmithKline Plc and later this year on one from NewLink Genetics Corp.
The US Department of Health and Human Services said on Tuesday a federal contract worth up to $42.3 million would help accelerate testing of an experimental Ebola virus treatment being developed by privately held Mapp Biopharmaceutical Inc.
Dr David Nabarro, senior UN Coordinator for Ebola, said the cost of getting the supplies needed by West Africa countries to control the crisis would amount to $600 million. That was higher than an estimate of $490 million by the WHO last week.
Moving workers and supplies around the region has been made difficult by restrictions by some countries on air travel and landing rights as they try to control Ebola's spread.
"We are working intensively with those governments to encourage them to commit to the movement of people and planes and at the same time deal with anxieties about the possibility of infection," Nabarro said.
He said the president of Ghana has agreed to allow an airbridge, or route, through the country to affected regions to move people and supplies.
Ivory Coast, which closed its borders with Liberia and Guinea last month, said on Tuesday it would open humanitarian and economic corridors to its two western neighbors.
Since Ebola was first detected in Congo in 1976, WHO has reported more than 20 outbreaks in Africa and 1,590 victims.
The WHO warned last week that the Ebola epidemic in West Africa could infect more than 20,000 people and spread to 10 countries.
Worries virus could mutate
Dr Thomas Kenyon, director of the US Centers for Disease Control and Prevention (CDC) Centre for Global Health, said on Wednesday the outbreak was "spiralling out of control" and warned that the window of opportunity for controlling it was closing.
"Guinea did show that with action, they brought it partially under control. But unfortunately it is back on the increase now," he told a conference call. "It's not under control anywhere."
He warned that the longer the outbreak went uncontained, the greater the possibility the virus could mutate, making it more difficult to contain. While Ebola is transmitted in humans by contact with bodily fluids of the sick, suspected cases of airborne infection have been reported in monkeys in laboratories.
A senior US official rebutted a call from global aid organization Medecins Sans Frontieres (MSF) for wealthy nations to deploy specialised biological disaster response teams to the region. MSF on Tuesday had warned that 800 more beds for Ebola patients were urgently needed in the Liberian capital Monrovia alone.
"I don't think at this point deploying biological incident response teams is exactly what's needed," said Gayle Smith, Special Assistant to the President and Senior Director for Development and Democracy on the National Security Council.
She said the US government was focusing on rapidly increasing the number of Ebola treatment centers in affected countries, providing protective equipment, and training local staff. "We will see a considerable ramp-up in the coming days and weeks. If we find it is still moving out of control, we will look at other options," Smith told a conference call.