Complicating matters, the countries hit hardest by the epidemic have major medical infrastructure challenges.
There is also a real sense of mistrust toward health workers from communities. In Sierra Leone and Guinea, WHO has said that community members have thrown stones at health care workers trying to investigate the outbreak.
MSF has treated 470 people, it said last week, of which 215 were confirmed cases.
However, it is now "having difficulty responding to the large number of new cases and locations," it said.
While public anxiety is high, the statement said, governments and civil society groups are doing too little to acknowledge the scale of the epidemic or educate people about how to stop the spread of the disease.
Another organization helping victims is Samaritan's Purse, an international Christian aid group. It has doctors in Monrovia, the capital of Liberia, and near the border with Guinea.
Virus 'should be easy to stop'
There is no cure for Ebola, but in theory the disease should be easy to fight, Piot told CNN.
"You need really close contact to become infected. So just being on the bus with someone with Ebola, that's not a problem."
Simple hygienic measures like washing with soap and water, not re-using syringes, and avoiding contact with infected corpses are sufficient to stop spread of the disease, Piot said.
"This is an epidemic of dysfunctional health systems," he added. "Fear of the virus, and the lack of trust in government, in the health system, is as bad as the actual virus."