Can animals be infected by people?
Yes. The primary host for Ebola, that is the animal that hosts ebola between human outbreaks,
is unknown. A primary suspect is the fruit bat, which has been found near the starting
point of many outbreaks. Generally in the primary host an infection is relatively
mild. Ebola also infects other animals, and results in an illness of varying degrees
of severity. In close human relatives such as chimps and gorillas, it is usually fatal.
An Ebola outbreak is suspected in the death of 6000 gorillas. Dogs in equatorial Africa
have been found to have antibodies against Ebola, meaning they have been exposed, but
Ebola does not seem to make dogs sick. Pigs also can be infected with Ebola, and they
do get sick, typically for about a week, but usually the illness is non-fatal for them.
Can Ebola become airborne?
Probably in the right circumstances. We know that infected piglets can transmit the virus
to monkeys due to controlled experiments recently carried out in Canada. It is also
notable that a previous scourge of humanity, the bubonic plague, typically starts
as an infection on the skin, and is not directly transmissible this way. However
if instead of the skin, a person is first infected in the respiratory track, this
results in much coughing, and does cause the disease to become airborne, resulting
in the more severe, pneumonic, form of the plague. There is no scientific evidence
that suggests that Ebola can not or will not become airborne. (Jim Kent)
If a single infected person were to enter a new country, would that be enough to start an outbreak in that country?
Potentially. Commercial flights have shut down in most afflicted areas. However there
was a case of a man infected in Liberia who flew to Lagos, Nigeria. An outbreak
quickly followed in his wake. With heroic efforts the Nigerian CDC and related
groups were able to contain the outbreak to 20 cases total of whom 8 died.
(http://www.cdc.gov/mmwr/preview/mmwrhtml/mm63e0930a2.htm?s_cid=mm63e030a2_e)
On the other hand, in Senegal a single traveler entered the country with Ebola,
but nobody was infected. Part of the reason for this good fortune was because
the authorities in Guinea, where he picked up the infection, alreted the correct authorities
in Senegal as part of their "contract tracing" within Guinea.
(http://www.cdc.gov/mmwr/preview/mmwrhtml/mm63e0930a3.htm?s_cid=mm63e030a3_e)