Ebola is a contagious viral disease that attacks the digestive system from the mouth to anus, the kidneys, the circulatory system, the liver and in less severe degree the skin, eyes, nose and ears, resulting in multiple organ failure.
The disease is 40-60% lethal with treatment and near 100% lethal without treatment. It appears to be a new disease, at least among humans, discovered first in areas of Zaire in 1976. Up to now there has been several outbreaks of the disease, most of them in restricted areas in Western Africa. Around 1850 persons have been attacked by mid 2014, of which 1200 died.
The disease is caused by a group of several similar viruses, called Ebolavirus, in the family Filoviridae of the order Mononegavirales. The viruses are shaped like tubes, sometimes branched tubes, and use single-stranded RNA as material for genetic coding. Therefore the infected cells are commanded to make a corresponding DNA copy by means of the enzyme reverse transcriptase. The DNA copy is used by the infected cell for the production of viral protein and new viral RNA.
The virus spreads from person to person by exchange of blood, corporeal fluids and other materials from the body. It can also spread with animals that transmit body material through biting, for example by fruit bats. The virus does not spread easily through air at a long distance from one human to another. It is however very contagious by close human contact, and medical personal will be in great danger without using unpermeable clothes and filtration of the air they breath.
An epidemic usually begins when a human comes in touch with body fluids, body parts or body products like feces or urine from an infected animal, or is bitten by an infected animal, most commonly a monkey, a chimp, a pig or a fruit bat. The disease seems to be permanently present in populations of these animals without making the animals severely ill.
During epidemies in 2014 the disease has spread more rapidly out of traditional restricted zones to wider areas in Western Africa. This might indicate new strains of the virus capable of more rapid transmission or a spread of animals that carry the virus.
The incubation period varies from two days to three weeks. In that period the disease is little contagious. The disease then suddenly begins with high fever, sore throat, lethargy, muscle and joint ache and severe headache.
Later there will be nausea, stomach pain, diarrhea, vomiting, swallowing problems and elevated rashes. The function of the liver, kidneys and circulatory system can suffer gravely due to tissue death, inner bleeding, blood coagulation, and disturbances in the distribution of body fluids. The blood pressure can fall dangerously. Patient will often bleed from the eyes. Also tissue destruction and bleeding inside the skin can occur.
In severe cases near death more extensive tissue destruction inside body cavities can occur, resulting in bleeding from the ears, the nose, in the mouth and through the rectum. The death is caused by simultaneous failure of several organs. As the disease proceed, it results in severe weight loss and weakness, and the reconvalescent period is long.
Early symptoms of the disease can resemble many other feverish diseases with bleedings, like typhoid or malaria. For a secure diagnosis one tests immunological reactions and the presence of enzymes linked to the viral infection in blood samples.
There is no vaccine and no treatment directly against the viral infection as by 2014, but vaccines are being developed. Treatment consists of supporting the body with oxygen, fluid, electrolytes, nourishment, circulation support, blood transfusion and other types of support as long as the infection is active and in the reconvalescent period.
Infected patients are isolated and populations that house infected individuals are also isolated by restriction entering and leaving the afflicted area. Medical personal and support staff that go near to the patients use unpermeable clothes around themselves and all the air they breath is filtered. In advanced treatment settings, the patient is shielded from the surroundings with unpenetrable barriers and air filters.