A person usually has within two to 21 days from initial exposure to the Ebola virus before they begin to show symptoms. Once symptoms begin, however, death can occur within six to 16 days. How exactly does this virus kill an otherwise perfectly healthy person so fast? Well, it all has to do with how the virus specifically attacks and disables our body’s immune system. YouTube channel Kurzgesagt- In a Nutshell gives a quick and efficient explanation of how this happens.

When Ebola initially enters a body, it first attacks the dendritic cells, which are essential messengers in the immune system. Normally at the onset of infection, these dendritic cells will activate an army of immune system cells to wipe out the “enemy” in a matter of days. However, Ebola takes over these cells, preventing them from sending out defense orders and instead causing them to order other immune system cells to prematurely end their own lives. At the same time this is occurring, the Ebola virus also turns the dendritic cells into essentially “Ebola-creating factories,” pouring out thousands of replications of the virus to continue this destruction process throughout the entire body.

In a desperate effort to stay alive, the immune system launches a cytokine storm, releasing all its defenses at once. While this does damage the virus, it leaves collateral damage in the blood vessels.

As the virus is attacking the immune system, it also tricks the body into releasing fluids, such as vomit. All this fluid release causes the infected individual to become extremely dehydrated. They start to bleed both internally and externally, and soon there is not enough blood left to supply the body with oxygen. The cells begin to die rapidly. The virus also attacks the liver, causing organ failure and more internal bleeding. It’s at this point where a person’s death is almost imminent.