Part of the problem is that health officials really have no idea how many people could be exposed inside the regions as many do not trust health care providers. Quarantining entire areas is probably the safest thing that can be done right now.

"Its size is due in part to weaknesses in the affected countries’ health systems and a lack of trust in the health workers who are struggling to combat the virus" [0]

Not sure the reliability of this source, but "The health security situation is worsened by an apparent lack of trust by the local population in their own governments and medical staff. Warnings against the consumption and selling of bush meat for instance have largely fallen on deaf ears with an inherent belief of the local populations that Ebola either must be a myth or a scam on behalf of corrupt politicians to deprive them of their most basic needs and livelihoods." [1]

[0] - http://www.intrahealth.org/page/ebola-outbreak-underscores-n...

[1] - http://www.securitynewsdesk.com/2014/08/12/ebola-west-africa...