What is it?
If there’s one disease that has dominated the media over the last few years, it’s undoubtedly Ebola. The outbreak in Western Africa, lasting from 2013 to 2016, claimed 11 325 lives and caused worldwide panic. About 50% of infections have lead to death.
Ebola is classified as a viral hemorrhagic fever, which means that the viral infection causes fever and bleeding. Early symptoms are those typical to influenza, accompanied by a high fever. Later vomiting, diarrhea, rashes, and chest pain can occur. All those infected have problems with blood clotting and, in around half the cases, they start bleeding internally or externally from mucous membranes or sites of needle punctures. Death is most often due to low blood pressure caused by fluid loss.
What causes it?
Ebola is caused by the infection of not one, but one of four different viruses belonging to the Ebola group. Between people, Ebola spreads through direct contact with bodily fluids such as blood, feces, and vomit. Corpses remain infectious, and traditional burial rituals have been a major factor in spreading the disease. Bats are the carriers of Ebola (they can have the virus in their system without showing symptoms), and contact with their tissues is believed to have been the origin of the recent outbreak.
What happens during it?
A virus is not a living thing. Is is a protein shell (sometimes also carrying an outer lipid layer) that holds genetic information. Viruses reproduce by invading a living cell and making it a factory that produces new viruses according to the instructions in the genetic material. This causes the cell to die, and sufficient damage to the cells of a being is the reason for symptoms in viral diseases.
While some viruses can only invade one type of cells, Ebola can invade many. Its main targets include many cells of the immune system, the cells that line the insides of blood vessels (endothelial cells), and liver cells.
Immune cells are the first ones to come in to contact with the virus. They carry it to lymph nodes, where there are plenty of other immune cells to invade and where the viruses reproduce before entering the circulation and spreading around the body. Cytokines are molecules responsible for provoking inflammation when they come into contact with something unknown. When the viruses have reproduced and interacted with cytokines, the level of their activation is so overwhelming to the body that the influenza-like symptoms occur.
A certain immune cell, the T cell, is responsible for detecting cells infected with viruses and helping to start the process of destroying the invader. Another immune cell, the dendritic cell, has the job of activating the T cells to do their thing. Ebola invades and disables the dendritic cells and that way the T cells stay passive. This explains in part the weakened immune response of those exposed and, consequentially, how easy it is for the virus to do further damage since the body’s usual line of defense isn’t functioning.
The later symptoms begin when the viruses have replicated and burst out of the immune cells. They produce a glycoprotein that attaches to the endothelial cells inside the blood vessels and increases the permeability of the vessels, causing blood to leak out. Some infected cells also release proteins that cause the blood to clot. These clots prevent the normal flow of blood and reduce the blood supply of important organs.
How is it treated?
Unfortunately, there isn’t any effective treatment for Ebola. Sometimes the body is able to fight the infection off, and most care is based on supporting this process. Since dehydration is a severe problem it’s a priority to get fluids inside the patient, either by drinking or injecting it to a vein. Other symptoms such as fever, pain, nausea, and anxiety are also tried to relieve. Many approaches are aimed at blood-related problems, such as trying to dissolve clots, adding blood cells or blood plasma, or trying to decrease bleeding by adding clotting factors.
Some research on vaccines has shown promising results but no significant breakthroughs have been made, and research is difficult because of the small number of people to study.
Sources: https://en.wikipedia.org/wiki/Ebola_virus_disease, http://www.sciencemag.org/news/2014/08/what-does-ebola-actually-do, http://www.md-health.com/What-Does-Ebola-Do-to-the-Body.html, http://www.bu.edu/today/2014/how-ebola-kills/, http://www.huffingtonpost.com/2014/08/02/ebola-symptoms-infection-virus_n_5639456.html