Story highlights It's "going to be tough and it's going to be costly to stamp out this outbreak," WHO official says

34 people are suspected to have been infected with Ebola in the new outbreak; 18 have died

Mobile labs and hospitals are being deployed

(CNN) The World Health Organization is preparing for the "worst-case scenario" as it continues to respond to the Ebola outbreak in the Democratic Republic of Congo.

Peter Salama, deputy director-general of emergency preparedness and response at the WHO, said in Geneva, Switzerland, on Friday that it's "going to be tough and it's going to be costly to stamp out this outbreak."

There have been 34 cases of Ebola virus disease reported during the past five weeks, the WHO said Friday. Of those, two have been confirmed using laboratory tests, 14 are suspected, and 18 -- who are deceased -- are considered probable for the disease. Three of the patients are health care workers.

"The number of suspected, probable and confirmed cases is significant, so we are very concerned, and we are planning for all scenarios, including the worst-case scenario," Salama said.

Ebola virus disease, which most commonly affects people and nonhuman primates such as monkeys, gorillas and chimpanzees, is caused by one of five Ebola viruses. On average, about 50% of people who become ill with Ebola die.

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