I am hoping that there's not a suitable animal species here to act as a "storage tank" for the virus. The disease wreaks havoc in Africa for many reasons, and one of the main ones is that the virus lurks in wild animal populations even when there are no current outbreaks. It seems human beings are a poor long term vector for the virus, it simply kills too quickly and in too great proportion.
While I share your concern that an animal could become a means of ebola transmission here in North America I am not at all sure about where it hides between outbreaks.
I have been reading a LOT about ebola and from what I have read there is way more that is unknown than is known. This is especially true of where ebola (and Marburg) hides when it isn't busy killing humans.
For instance, one of the earliest known* cases of someone infected with a filovirus (in this case, Marburg) is that of Charles Monet (I excerpted a big chunk of his story from "The Hot Zone" in the other ebola thread in order to describe the progression of the disease and the symptoms), a French expat living in western Kenya. It is theorized that he acquired his infection while on a hiking vacation. During that time he visited a cave on the side of Mount Elgon. Monet visited Kitum Cave on January 1st, 1980 and began to show serious symptoms of a hemorrhagic fever about a week afterward. So the question then is obvious...did he contract the disease inside of the cave, a place that is loaded with fruit bats and their crap? Or was it something else?
In 1987 a second victim (a ten-year-old male) came down with Marburg. He, too, had visited Kitum Cave just before he became symptomatic.
In 1988 the US Army underwrote a massive investigation of Kitum Cave that involved studying tens of thousands of samples...insects, excrement, soil samples, water samples, air samples...the researchers attempted to infect live monkeys by putting their cages all throughout the cave, etc. In essence they sampled everything that they could think of. They found nothing.
Ebola has been the same way. The investigators have looked far and wide and they have found nothing as to where the disease hides between outbreaks.
Another problem: Ebola and Marburg tend to have such a high mortality rate that outbreaks don't last long enough for researchers to discover very much about it in humans. And let's face it, these are the only times that it can be studied...no one is going to experiment on humans with these diseases because that would be murder, pure and simple.
Which leads us to where we are today. We currently have an ebola outbreak that has a relatively low mortality rate. That's both good and bad. It's good that only about half of the victims die. But because it has a lower mortality rate it is able to spread in a more persistent manner: This time the outbreak isn't ending quickly. It is demonstrating "staying" power. In this way it is like HIV. HIV is a permanent fixture of humans because it takes so long to kill its victims. It is entirely possible that this current strain of ebola will NOT burn out and/or fade away. Not in the third world, anyway.
And let's add one more huge uncertainty, the completely unknown aspect of mutation. As the virus jumps from one host to another it has the ability to mutate. What those mutations can and will be no one knows. It may become airborne. It may become more or less lethal. It may become more or less easily acquired. No one knows.
We know a lot more today about HIV than we did thirty years ago. But the only reason that we know more is because it has been with us and we have had all kinds of opportunity to study it. We may be at the beginning of a long study period with this particular strain of ebola. No one knows.
*The earliest known case of ebola was in September of 1976 where it affected about fifty-five villages near the headwaters of the Ebola River.
EDIT:
Spanish government orders nurse's dog euthanized. Because we smart and you dumb.