By Kim Smiley

Scientists believe they have identified the origin of the ongoing Ebola outbreak.  The first person believed to have contracted Ebola was a two-year-old boy named Emile Ouamouno from a village called Meliandou in Guinea.  The fact that patient zero was a small child is unusual since he is too young to have been a hunter or travel far from the village alone.  His exposure to bushmeat, which has been identified as a likely culprit for transmission to humans in previous Ebola outbreaks, was also limited.

So how did a young boy contract Ebola?  A Cause Map, a form of visual root cause analysis, can be built to help analyze this issue.  A Cause Map intuitively lays out the causes that contributed to a problem to show the cause-and-effect relationships.  (Click on “Download PDF” above to view a high level Cause Map.)  As the Cause Map shows, researchers believe the boy was exposed to bats that carried Ebola.

Children from the village liked to play in a nearby hollow tree filled with Angolan free-tailed bats. Researchers believe that the boy may have come into contact with either bats infected with Ebola or their feces.   Unfortunately, the tree burned in the time since the Ebola epidemic started and researchers were unable to take samples from it, so it cannot be confirmed conclusively that the bats in the tree spread Ebola.  This information would have been particularly useful because this species of bats has not been previously linked to Ebola and Angolan free-tailed bats commonly live near people.  The scientists were able to rule out larger mammals such as chimpanzees and antelopes as the source of the current outbreak.

Tracking the origins of Ebola has proved difficult, in part because Ebola is a zoonotic disease, meaning that it can be transmitted between species.  Bats have long been suspected of being carriers of Ebola, but scientists have never been able to conclusively prove which animals are responsible for human Ebola outbreaks.  Ebola outbreaks tend to occur in remote areas where it’s difficult to gather data in a timely manner, especially in the midst of an Ebola outbreak.  Cultural differences can also make research difficult because local populations are often suspicious of the researchers, many of who are foreigners.

The current Ebola outbreak has killed nearly 8,000 people and is still spreading.  As populations grow and people are exposed to more animals, outbreaks like this may become more common.  If the species responsible for spreading Ebola could be identified, researchers would be better able to prevent future Ebola cases and possibly prevent outbreaks from occurring.

If you are curious, here are some interesting articles on lessons learned during the Ebola Outbreak –

Malaria killing thousands more than Ebola in West Africa

Ebola’s lessons, painfully learned at great cost in dollars and human lives