Geneva (AFP) - Top Ebola experts raised grave concerns Thursday about the worsening epidemic in west Africa as the number of infections soared to almost 10,000 and the death toll edged closer to 4,900.
The World Heath Organization said after an emergency meeting on the deadly haemorrhagic fever that the situation in the worst-hit countries of Guinea, Liberia and Sierra Leone "remains of great concern" as cases increase exponentially.
A total of 976 cases have come in the last seven days alone, said Isabelle Nuttall, head of the UN agency's alert division.
WHO said the outbreak remains "a public health emergency of international concern".
It formally declared a global emergency in August, sparking outside criticism and internal soul-searching over claims that it was too slow, as the first case was in Guinea in December.
WHO's deputy chief, Keiji Fukuda, said the international community had for months been ramping up the fight, with 600 international experts deployed in the embattled region over recent weeks.
Its "70/70" plan aims by December to ensure 70 percent of people infected by Ebola are placed in medical isolation, and, given that dead bodies can spread the virus, to ensure 70 percent of burials are conducted safely.
- 'Race against time' -
"By the beginning of December, we hope to see a bend in the curve. It's clear that it remains quite a challenge right now," Fukuda said.
He pointed to major efforts to "break the chain of transmission" by setting up special Ebola wards to try to save the lives of those struck by the virus and stem fresh infections.
"But it has been terrifically difficult to get enough health workers -- both domestic health workers as well as international health workers -- and this continues to be one of the major challenges," he said.
Health workers have paid a heavy price, with 244 deaths out of 443 cases across the affected countries.
The hunt is on for a vaccine, with supplies of Canadian-discovered experimental vaccine rVSV arriving in Geneva for a new round of trials.
Hopes are also centred on ChAd3, an experimental vaccine made by British company GlaxoSmithKline.
Whichever proves its mettle in trials, WHO hopes to deploy tens of thousands of doses to Africa by early 2015 for "real-world" tests.
WHO held closed-door talks Thursday on the issue of access to and financing vaccines, as officials said costs could be in the "hundreds of millions" of dollars.
At a meeting Thursday, the European Union fast-tracked 24.4 million euros ($31 million) to find vaccines and treatments.
"We're in a race against time on Ebola and we must address both the emergency situation and at the same time have a long term response," said EU chief Jose Manuel Barroso.
- No to travel ban -
Stemming Ebola in Guinea, Liberia and Sierra Leone remains the top priority, the WHO said.
Besides battling Ebola within their borders with "leadership, community engagement, bringing in more partners, paying staff on time, and accountability", exit screening of air, land and sea travellers remains critical, it said.
The agency reiterated its opposition to any general ban on travel or trade with the region, saying it would pile on more economic hardship and raise the risk of "uncontrolled migration of people from affected countries, raising the risk of international spread of Ebola".
Senegal and Nigeria, which together had a handful of cases, were declared Ebola-free by the WHO on Friday and Monday, respectively, and have won praise for their rapid fightback against the disease.
Despite concerns that the virus could raise its head in other west African nations, Fukuda said Ebola's stark impact actually helped track it.
"You simply would not be able to cover up having lots of people die for mysterious reasons. There is reasonable confidence right now that we are not seeing widespread transmission Ebola into the neighbouring countries," he said.
International alarm has been stoked by cases beyond Africa.
Spain has seen one non-fatal infection, a nurse who caught Ebola from a patient she cared for, a missionary who died of Ebola after returning from Liberia.
In the United States, two nurses fell ill after caring for a Liberian man who died from the disease on October 8, the first Ebola case to be diagnosed on US soil.
One of the American nurses no one longer has the virus, her family said Wednesday. The other nurse remains in a stable condition in hospital.
"Certainly, one should have a very healthy respect for this infection. And certainly, there are instances where fear makes sense," said Fukuda.
But he warned against letting the Ebola rumour-mill spin out of control.
On the ground, the situation remained deeply worrying, with Liberian President Ellen Johnson Sirleaf admitting "the transmission just ran ahead of us" as she introduced new border controls.
In neighbouring Sierra Leone, two people died in a riot which erupted Tuesday when health workers tried to take a blood sample from a 90-year-old woman suspected of having Ebola.
But in rare good news, a Doctors Without Borders team working in the northern Liberian town of Foya told Sirleaf it could soon be declared Ebola-free, after no new cases had been reported in three weeks.