Jrinne - the fruit bat is one host. There are others such as primates, pigs, dogs, etc. It is speculated that some breakouts may have started by eating contaminated wild animals.
ehensim1 - the disease was shown by experiment to be transmitted through air using monkeys. The reason why there is no observed airborne transmission in humans is not fully understood but likely there is insufficient virus in the lungs. In any case, the virus exists in human saliva, which can be thrown while talking (i.e. spit) and can end up in someone’s eye.
Anyways, this situation could break down very easily, even in the USA. Here are some articles:
http://www.theguardian.com/world/2014/oct/25/ebola-cases-10000-mali-death
“The international community badly misjudged the impact of the Ebola epidemic in its first few months and is compounding that error by failing to act quickly enough now.”
“The New York Daily News claimed that an unusually high number of hospital workers have reported in sick since Spencer’s arrival.”
Nurse returning from Africa … “I am scared that, like me, they will arrive and see a frenzy of disorganisation, fear and, most frightening, quarantine.”
http://www.newscientist.com/article/dn26354-ebola-could-never-spread-widely-here-could-it.html
Nigeria… “But to find the 20 people subsequently infected required 18,500 visits to monitor 900 people quarantined after coming into contact with infected people, and cost $30 million.”
“General John Kelly … , warned this week that if Ebola epidemics break out in that region (South and Central America), people may run for the US… Already … many West Africans are smuggled overland into the US.”
“There were just over 8000 cases of SARS worldwide, and by the end global supplies of surgical masks were exhausted.” Comment: there will potentially 10,000 new Ebola cases a week by January.