Ebola virus diseaseThe number of new Ebola cases in West Africa is growing faster than authorities can manage them, the World Health Organization (WHO) said on Friday, renewing a call for health workers from around the world to go to the region to help.

As the death toll rose to more than 2,400 people out of 4,784 cases, WHO director general, Margaret Chan, said the vast nature of the outbreak — particularly in the three hardest-hit countries of Guinea, Liberia and Sierra Leone — required a massive emergency response.

“The Ebola outbreak that is ravaging parts of West Africa is the largest, most complex and most severe in the almost four-decade history of this disease,” she told reporters on an international teleconference from Geneva.

“The number of new patients is moving far faster than the capacity to manage them. We need to surge at least three to four times to catch up with the outbreaks.”

Chan called for urgent international support in sending doctors, nurses, medical supplies and aid to the worst-affected countries.

“The thing we need most is people,” she said. “The right people, the right specialists, and specialists who are appropriately trained and know how to keep themselves safe.”

The Ebola infection rate and death toll have been particularly high among health workers, who are exposed to hundreds of highly infectious patients who can pass the virus on through body fluids such as blood and excrement.

Some foreign healthcare workers, including several Americans and at least one Briton, have also become infected while working with patients in West Africa, had also contracted the disease.

Speaking at the same briefing, Cuba’s minister for Public Health, Roberto Morales Ojeda, said his country would be sending 165 healthcare workers to help in the fight – the largest contingent of foreign doctors and nurses to be committed so far.

Chan welcomed Cuba’s move and urged others to follow suit.

“If we are going to go to war with Ebola, we need the resources to fight,” she said. “We still need about 500 to 600 doctors coming from abroad and at least 1,000 or more health care workers.”

She said the three worst affected countries were also running low on “almost everything” – including personal protective equipment, basic medical supplies and body bags.

“Today there is not one single bed available for the treatment of an Ebola patient in the entire country of Liberia,” she said.

Although the latest figures show more than 2,400 people have died of Ebola virus infection in West Africa since the epidemic started in March, Chan said even the most up-to-date tolls were likely to lag far behind the reality on the ground.

“Whatever number of cases and deaths we are reporting is an underestimate,” she said.

The U.N. health agency had previously warned there could be as many as 20,000 cases in the region before the outbreak is brought under control.

The International Monetary Fund said on Thursday that economic growth in Liberia and Sierra Leone could decline by as much as 3.5 percentage points due to the outbreak, which it said had crippled their mining, agriculture and services sectors.