Three Ebola-stricken countries will seek nearly $700 million in aid at a U.N. conference this week to rebuild their devastated health care systems, the World Health Organization said.

Guinea, Liberia and Sierra Leone, which are all experiencing a resurgence of the deadly hemorrhagic fever, have budgeted a little more than $2 billion between them to restore their health systems.

But, according to WHO, to reach that goal they will still need $696 million in aid from donor nations.

The Ebola epidemic, which has claimed more than 11,200 lives so far, took an exceptional toll on health workers who were up to 30 times more likely to contract the disease than the general public because of the number of patients they treated, WHO found.

During one 15-month period some 800 health workers contracted Ebola across the three countries and more than half were nurses and nurse aides.

In rural clinics, there may only be one nurse for hundreds of patients, said Yolanda Ogbolu, deputy director of Global Health at the University of Maryland School of Nursing.

"Losing a nurse in a place like Liberia is very significant," said Ogbolu, a neonatal specialist who has trained nurses in Liberia and Nigeria. "They are working in the absence of a physician and frequently have to work alone."

"It means there is no one to take care of a mother about to deliver a baby or someone who walks in with malaria," she said.

Malaria, which mimics some of the same symptoms of Ebola, is the main cause of morbidity and mortality in Liberia, according to the U.S. Centers for Disease Control and Prevention (CDC).

Sister Barbara Brillant, president of Mother Patern College of Health Sciences in Liberia's capital Monrovia, said that in the epidemic's early days people feared going to hospitals and clinics because they didn't trust the health system.

"Why? Health workers were dying and they thought these are the people who are giving it to us, not trying to save us," she told the National Catholic Reporter.

Health workers either did not have or did not know how to use the proper personal protective equipment.

"There are various levels of protection health care providers must have when they are dealing with potentially fatal diseases. Not just Ebola, but small pox or anthrax or any Category A biological agent," said Tener Goodwin Veenema, an associate professor at John Hopkins School of Nursing and an expert in disaster nursing and public health emergency preparedness.

"And the health care providers must be properly trained in how to 'don and doff' personal protective equipment," she said.

John Hopkins Armstrong Institute worked with CDC to come up with video tutorials on how to safely put on and take off the special gowns, masks, shields, gloves and booties without infecting others.

"These countries didn't have a solid public health care system to even help them begin to respond," Veenema said. "What they need is to build a health care workforce and that is a global challenge right now."

The World Bank Group said it has mobilized $1.62 billion in financing for Ebola response and recovery efforts to support the countries hardest hit by Ebola.

The United States, as of last week, had pledged $1.2 billion to the three West African nations.

Sr. Barbara, in an email to Thomson Reuters Foundation, said she would like to see funding spent on better salaries and better training for health workers.