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The Ebola epidemic in West Africa is an international emergency - that was the declaration today from the World Health Organization. It said the outbreak won't be stopped unless the global community drastically scales up its response. The virus has now killed nearly a thousand people, mostly Sierra Leone, Liberia and Guinea. It's also spread to Nigeria which has declared a state of emergency. There are now a dozen cases in the country. We'll talk with a health advocate from Guinea about the challenges of containing disease. But first more from WHO's assessment, as NPR's Nurith Aizenman reports officials say the outbreak can't be controlled unless more health workers are put on the ground.

NURITH AIZENMAN, BYLINE: WHO officials are blunt about why the international community needs to step in. Here's the organization's director general, Dr. Margaret Chan.

MARGARET CHAN: Countries affected to date simply do not have the capacity to manage an outbreak of this size and complexity on their own.

AIZENMAN: Dr. Chan is referring to Guinea, where the outbreak started, and the two countries where it's now rapidly spreading - Sierra Leone and Liberia. She says that all three of these places have been trying to rebuild from years of civil unrest. There desperately short on supplies, especially the kind that you need with Ebola - protective gear and diagnostic tests. Dr. Keiji Fukada is in charge of health security at the WHO, and he says it gets even worse.

KEIJI FUKADA: We have seen that in some of the facilities, some of the basic needs are unreliable so for example, running water or continuous electricity.

AIZENMAN: None of this is surprising to Dr. Frank Glover. He's a urologist who spends four months out of every year working in Liberia with the aid group SHIELD. He testified about the outbreak before Congress yesterday, and he says yes, even before the outbreak Liberia's health system was threadbare.

FRANK GLOVER: Well, you have a population of four million people and only 150 doctors.

AIZENMAN: And most of those doctors weren't even from Liberia. And then when the Ebola virus started to spread in March...

GLOVER: Most of those doctors - expatriates went back to their home countries, leaving Liberia with only 50 doctors for this four million population.

AIZENMAN: Dr. Glover doesn't blame them for leaving. They didn't have the tools they needed to protect themselves and the local doctors and nurses - a lot of them started to get sick. Dr. Glover says others abandoned post because they didn't even have simple gloves. Ebola is spread through direct contact with the bodily fluids of infected people, so not having gloves - it's a problem. That same lack of protection has plagued health workers in neighboring Guinea and Sierra Leone. Overall, as many as 150 health workers have now fallen ill and about 80 have died. Right now there are only two treatment centers for Ebola in Liberia, staffed by just a handful of doctors.

GLOVER: So every day patients with Ebola are having to be turned away simply because they don't have the capacity, and this is why it's so devastating.

AIZENMAN: They go home and then they infect their family and friends. The WHO officials acknowledged all of this today, and they say it has to change. To stop the spread, these countries need more health workers - a lot more. So asked Dr. Glover, where will these people come from?

GLOVER: I don't think people are going to come.

AIZENMAN: He wonders - who would take the risk? He doesn't have an easy solution for right now, but he's thinking about the future. Once they get past this crisis, it's going to be crucial to train as many doctors and nurses as possible who are locals or at least Africans.

GLOVER: Those are the people that will stay in an outbreak like this.

AIZENMAN: Nurith Aizenman, NPR News. Transcript provided by NPR, Copyright NPR.