The countries involved in the epidemic are not structured to handle this size of outbreaks. Strong support in the past week from NGOs and foreign governments has yet to be converted into tangible results (and likely won't for additional days/weeks). The majority of people within these countries do not understand what is currently happening (lack of educational/medical understanding). Quarantine is a less preferable option for a dying patient compared to dying next to loved ones, causing further transmission of the disease.
Another reason for spread include Doctors/Nurses relying on others' memories to know whether or not a patient is an ebola risk in a health clinic. If the patient turns out to be a risk then that clinic must close for 21 days. 155 healthcare workers have died so far.