Two key reasons Zaire Ebolavirus will spread rapidly and ceaselessly if even a handful of patients were infected by the now deceased Thomas Eric Duncan are as follows:
1). FLU SEASON: Many US citizens will visit the doctor for minor health concerns that people from foreign nations would not. People are often unconcerned with cost, because they realize their insurance will pay. As a result, many will seek analysis of their condition at the first signs of trouble. A mild fever may send the first dozen patients infected by Duncan to the local hospital. Flu season will likely blind doctors to the possibility of Ebola. The two viruses will be difficult to differentiate initially. Furthermore, the onerous task of putting a full hazmat suit on properly, taking a chemical shower, then carefully removing the garment each and every day, means that doctors will be unlikely to protect themselves during the preliminary surge. Various medical personnel will contract Ebola.
2). LACK OF CONCERN: There is a common public perception that Ebola is less of a concern than other deadly diseases that are contracted perennially. Tens of thousands die of Influenza almost every year. Meanwhile, there has only been one confirmed Ebola patient who first showed symptoms in the US. What this mindset fails to address is the death rate discrepancy between the two viruses. Something like one million people in the US contract Influenza each year. Thirty thousand die. 30,000 is a large number, but these deaths only represent a three percent mortality rate. Zaire Ebolavirus kills over half the people who contract it. This means if a million people contract Ebola, at least 500,000 people will die.