(CNN) -- Global health experts on Friday declared the Ebola epidemic ravaging West Africa an international health emergency that requires a coordinated global approach.

Guinea, Liberia and Sierra Leone are battling the Ebola virus, which has also spread to Nigeria. The virus is believed to have infected 1,779 people, killing 961, from the start of the outbreak earlier this year through Wednesday, the World Health Organization said.

"The possible consequences of further international spread are particularly serious in view of the virulence of the virus, the intensive community and health facility transmission patterns, and the weak health systems in the currently affected and most at-risk countries," WHO said Friday after two days of emergency meetings.

 

Initial Ebola response a 'failure'

The U.N. health agency described it as the worst outbreak in the four-decade history of tracking the disease.

Photos: Ebola outbreak in West Africa

 

Why Ebola drug isn't available in Africa

 

Step inside CDC's Ebola war room

"A coordinated international response is deemed essential to stop and reverse the international spread of Ebola," WHO said.

Ebola virus: 9 things to know about the killer disease

Medical aid groups applauded the designation but said that it alone won't reduce fatalities.

"Declaring Ebola an international public health emergency shows how seriously WHO is taking the current outbreak, but statements won't save lives," said Dr. Bart Janssens, director of operations for Doctors Without Borders, a humanitarian organization.

"Now we need this statement to translate into immediate action on the ground. For weeks, MSF has been repeating that a massive medical, epidemiological and public health response is desperately needed to save lives and reverse the course of the epidemic," said Janssens, using the initials for his organization's French name, Medecins Sans Frontieres.

"Lives are being lost because the response is too slow."

The agency said it has nearly 700 staff responding to the crisis in the affected countries. "All our Ebola experts are mobilized, we simply cannot do more," Janseens said.

American patient: 'I am growing stronger every day'

Two Americans who contracted Ebola while supporting efforts to fight the disease in Liberia are undergoing treatment at Emory University Hospital in Atlanta: Dr. Kent Brantly and aid worker Nancy Writebol. Emory is one of four U.S. institutions capable of providing such treatment.

Friday, Brantly released a statement saying doctors and nurses were giving him the best care possible.

"I am growing stronger every day, and I thank God for His mercy as I have wrestled with this terrible disease," Brantly wrote from his isolation room at Emory, according to Christian charity Samaritan's Purse, for which he worked. "I also want to extend my deep and sincere thanks to all of you who have been praying for my recovery as well as for Nancy and for the people of Liberia and West Africa."

David Writebol offered insights Friday on his wife's battle with Ebola. She had been working with the missionary group Serving in Mission to make sure health care workers didn't contract Ebola when she came down with the virus herself.

"I don't believe the problem was a failure in the established protocol," David Writebol said in press briefing from Liberia, where his wife got the disease. "... She had prepared herself."

He noted there have been "slight improvements" in his wife's condition since she's come to Atlanta. One plus for her? She asked for a coffee from Starbucks and got it -- something that wouldn't have been possible in Liberia.

David Writebol said plans are in the works for her to join his wife of 40 years in Atlanta, though right now they are an ocean apart.

And what would he do then, if he could?

"I would give her a kiss. Hold her."

WHO warns of bogus information

Meanwhile, a WHO official said bogus information is adding to the rapid spread of the disease.

"Perhaps one of the most important factors contributing to this is fear and misinformation," said Dr. Keiji Fukuda, assistant director for health security.

"This is critical to understand, because what it is doing is that it helps foster suspicion and anxiety in communities, and when that happens we see a situation where people are reluctant to go to health facilities or maybe reluctant to bring their family members there. And it underscores the importance of communities being aware and understanding, but we also see that fear impacts other countries."

Though infectious, Ebola "is not mysterious" and can be contained, Fukuda said.

Liberian President Ellen Johnson Sirleaf said the fast-spreading disease has overwhelmed her nation's health care system.

"The scope and scale of the epidemic ... now exceed the capacity and statutory responsibility of any one government agency or ministry," she said.

Map: Ebola outbreak

 

How an Ebola outbreak can start, and end

 

The facts about Ebola

The Liberian leader declared a 90-day state of emergency this week, which will allow her government to set up a series of measures to prevent the spread of the disease.

9 questions about this new Ebola drug

While Liberia struggles to contain the epidemic, the United States ordered relatives of its embassy employees to leave the country. The U.S. Embassy is in the capital of Monrovia, one of the areas hardest-hit by the epidemic.

Washington said it's sending experts to Liberia, including 12 specialists from the Centers for Disease Control and Prevention, and a 13-member disaster assistance response team from the U.S. Agency for International Development.

Ebola is here: 5 reasons not to panic

A patient in a Canadian hospital near Toronto has been isolated after showing flu-like symptoms after a recent trip to Nigeria, said public health spokeswoman Dr. Eileen de Villa.

The patient has been placed in the "appropriate infection control measures including isolation of the patient," De Villa said.

Those who have tested positive for Ebola so far include Dr. Modupeh Cole, according to sources at Connaught Hospital in Freetown, Sierra Leone. Cole is a senior physician at the hospital in the Sierra Leone capital.

And Nigerian Health Minister Onyebuchi Chukwu told reporters Friday -- with two more cases now confirmed -- that there have been nine Ebola cases in his country. Two of those -- including Patrick Sawyer, a Liberian government minister an American citizen who collapsed after getting off a plane in Nigeria -- have died.

Six more suspected cases are under investigation.

"The federal government has approved life insurance policies for all those who take care of Ebola virus patients involved in (tracking those who came in contact with Ebola)," Chukwu said.

The Ebola virus causes hemorrhagic fever that affects multiple organ systems in the body.

Early symptoms include weakness, muscle pain, headaches and a sore throat. They later progress to vomiting, diarrhea, impaired kidney and liver function -- and sometimes internal and external bleeding.

Ebola spreads through contact with organs and bodily fluids such as blood, saliva, urine and other secretions of infected people. It has no known cure. The most common treatment requires supporting organ functions and maintaining bodily fluids such as blood and water long enough for the body to fight off the infection.