Its very tragic and frightening but this endemic will not cause plague like death rates unless the virus mutates and transmits by a pneumonic process. Otherwise it will remain largely confined to Africa in endemic outbreaks. Educating the local populations about how it is transmitted and good hygiene is the best approach. Currently there is no cure or effective treatment.
So far the it is approximately doubling every week. By August 25 the new cases per day and new deaths per day should be twice what it is now.
You should catch up on your reading. Illegal immigrants have been nabbed in Albania and Pisa Italy, and some are showing symptoms. It can get as far as people can get in an incubation period that ranges from 2 to 21 days, depending on initial viral load.
In short, anywhere in the world, via air travel.
While most people in the affected region are too poor to even consider air travel, there are numerous natives and a host of US expatriates there working in the oil industry. The potential to spread globally exists. These will be people who do not yet know they are infected, unlike Sawyer, who likely knew and was already symptomatic when he was on the plane.