Scientists believe they have found the carrier of Ebola virus - fruit bats tested during outbreaks in Gabon and the Republic of Congo were found to be carrying it (without symptoms.)
The excellent factual book Hot Zone by Richard Preston is split into two parts: the first part describes Ebola and various outbreaks in Africa. The second part covers an outbreak in a monkey house in Washington by a virus showing properties identical in many ways to Ebola. (It killed the monkeys - but did not jump species .. much!)
In Hot Zone, a cave is found - Kitum cave - in Africa which links two separate single-incidence occurrences of Ebola. Scientists eventually go to the cave and take blood samples from absolutely everything they can find. (Except elephants - "Did you ever try to take a blood sample from an elephant?" - and big cats.) They found nothing at all and the results were never formally published. Kitum cave was absolutely stuffed with bats, so the fruit bat find could explain how two people died of Ebola in separate incidents after visiting Kitama cave.
A successful virus does not kill its host. It has a symbiotic relationship, the lack of serious harm to the host allows it to survive. When the traditional host of a virus is wiped out, the virus will try to jump species, and it will mutate. A virus that is benign to a moth may be a killer of humans. Viruses like meat ... and the largest source of meat on the planet is human. Conserving the environment can keep these killers in harmless hosts inside the rain forests and jungles of the world. Wipe out their environments and the hosts will die, the viruses will mutate and jump species, and we could be in serious trouble.
Fruit bats carry Ebola: http://news.bbc.co.uk/2/hi/health/4484494.stm
Richard Preston (Hot Zone author) has an excellent website.
Very useful information from the CDC relating to Ebola and many other viruses: http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/ebola.htm
Ebola and Marburg vaccines created: http://news.bbc.co.uk/2/hi/africa/4612339.stm
HIV and Ebola 'technology' used as delivery systems for Cystic Fibrosis Cure: http://news.bbc.co.uk/2/hi/health/4072626.stm