UCSC Ebola Genome Portal: Zoonotic Infections

General

Zoonosis describes the process by which an infective disease transmits between species. Thereby, zoonotic infections are those that can be transmitted across species. Throughout history zoonotic infections have hampered human proliferation. The bubonic plague, often referred to as the black death, stands as an infamous example. Other diseases such as rabies and HIV have become household names across the world. Ebola virus can be classified as a zoonotic infection. This webpage contains general information, links to papers and other resources related to zoonotic infections.

Fruit Bats

Fruit bats are believed to be a common vector for the Ebola virus. Due to their flight patterns fruit bats can cover many miles providing exposure to local fauna and peoples. This, in conjunction with the reliance of many native peoples on "bush meat" such as deer and bat as a gastronomic staple, has created an ideal environment for the Ebola virus to spread.

Environmental Concerns

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?

Possibly in the right circumstances. Controlled experiments recently carried out in Canada demonstrated that infected piglets could transmit the virus to monkeys. 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 tract, 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, alerted 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)

Links

From Pigs to Monkeys, Ebola Goes Airborne: Ebola virus transmits through airborne vectors