Where does it keep coming from? It's a real mystery.
Wikipedia tells us:
The
natural reservoir for Ebola has yet to be confirmed; however,
bats are considered to be the most likely candidate species.
[51] Three types of fruit bats (
Hypsignathus monstrosus,
Epomops franqueti and
Myonycteris torquata) were found to possibly carry the virus without getting sick.
[75] As of 2013, whether other animals are involved in its spread is not known.
[74]Plants,
arthropods,
rodents, and birds have also been considered possible viral reservoirs.
[1][23]
Bats were known to roost in the cotton factory in which the
first cases of the 1976 and 1979 outbreaks were observed, and they have also been implicated in Marburg virus infections in 1975 and 1980.
[76] Of 24 plant and 19 vertebrate species experimentally inoculated with EBOV, only bats became infected.
[77] The bats displayed no clinical signs of disease, which is considered evidence that these bats are a reservoir species of EBOV. In a 2002–2003 survey of 1,030 animals including 679 bats from
Gabon and the
Republic of the Congo, 13 fruit bats were found to contain EBOV RNA.
[78] Antibodies against Zaire and Reston viruses have been found in fruit bats in
Bangladesh, suggesting that these bats are also potential hosts of the virus and that the filoviruses are present in Asia.
[79]
Between 1976 and 1998, in 30,000 mammals, birds, reptiles, amphibians and
arthropods sampled from regions of EBOV outbreaks, no Ebola virus was detected apart from some genetic traces found in six rodents (belonging to the species
Mus setulosus and
Praomys) and one
shrew (
Sylvisorex ollula) collected from the
Central African Republic.
[76][80] However, further research efforts have not confirmed rodents as a reservoir.
[81] Traces of EBOV were detected in the carcasses of gorillas and chimpanzees during outbreaks in 2001 and 2003, which later became the source of human infections. However, the high rates of death in these species resulting from EBOV infection make it unlikely that these species represent a natural reservoir for the virus.
[76]
The CDC tells us:
Ebola Virus Disease (EVD) is a rare and deadly disease most commonly affecting people and nonhuman primates (monkeys, gorillas, and chimpanzees). It is caused by an infection with one of five known Ebola virus species, four of which can cause disease in people:
- Ebola virus (Zaire ebolavirus)
- Sudan virus (Sudan ebolavirus)
- Taï Forest virus (Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus)
- Bundibugyo virus (Bundibugyo ebolavirus)
- Reston virus (Reston ebolavirus), known to cause disease in nonhuman primates and pigs, but not in people
Ebola virus was first discovered in 1976 near the Ebola River in what is now the Democratic Republic of Congo. Since then, the virus has been infecting people from time to time, leading to
outbreaks in several African countries. Scientists do not know where Ebola virus comes from. However, based on the nature of similar viruses, they believe the virus is animal-borne, with bats being the most likely source. The bats carrying the virus can transmit it to other animals, like apes, monkeys, duikers and humans.
Scientific American suggests:
The hollow Cola tree growing in a remote area of southeastern Guinea was once home to thousands of bats routinely hunted and killed by the neighborhood children. It was also a popular spot to play. A year ago, one child in particular lived within fifty meters of the tree: a two-year-old boy who died in December 2013 and later was identified as the first person in west Africa known to have developed Ebola. The tree was one of the few that loomed over his home village of
Meliandou, a hamlet of 31 houses. The question that now haunts researchers: were the tree’s occupants behind how that small boy contracted the virus in the first place? Taken from "Where Does Ebola Come From" By
Dina Fine Maron on December 30, 2014