Ebola Virus Disease
Ebola virus disease (EVD; also Ebola hemorrhagic fever, or EHF), or simply Ebola, is a viral hemorrhagic fever of humans and other primates caused by ebolaviruses. Signs and symptoms typically start between two days and three weeks after contracting the virus with a fever, sore throat, muscular pain, and headaches. Then, vomiting, diarrhea and rash usually follow, along with decreased function of the liver and kidneys. At this time some people begin to bleed both internally and externally. The disease has a high risk of death, killing between 25 and 90 percent of those infected, with an average of about 50 percent.This is often due to low blood pressure from fluid loss, and typically follows six to sixteen days after symptoms appear
The length of time between exposure to the virus and the development of symptoms (incubation period) is between 2 to 21 days, and usually between 4 to 10 days. However, recent estimates based on mathematical models predict that around 5% of cases may take greater than 21 days to develop.
Symptoms usually begin with a sudden influenza-like stage characterized by feeling tired, fever, weakness, decreased appetite, muscular pain, joint pain, headache, and sore throat. The fever is usually higher than 38.3 °C (101 °F). This is often followed by vomiting, diarrhea and abdominal pain.Next, shortness of breath and chest pain may occur, along with swelling, headaches and confusion. In about half of the cases, the skin may develop a maculopapular rash, a flat red area covered with small bumps, 5 to 7 days after symptoms begin.
In some cases, internal and external bleeding may occur. This typically begins five to seven days after the first symptoms. All infected people show some decreased blood clotting. Bleeding from mucous membranes or from sites of needle punctures has been reported in 40–50 percent of cases. This may cause vomiting blood, coughing up of blood, or blood in stool. Bleeding into the skin may create petechiae, purpura, ecchymoses or hematomas (especially around needle injection sites. Bleeding into the whites of the eyes may also occur. Heavy bleeding is uncommon; if it occurs, it is usually located within the gastrointestinal tract.
Recovery and death
Recovery may begin between 7 and 14 days after first symptoms. Death, if it occurs, follows typically 6 to 16 days from first symptoms and is often due to low blood pressure from fluid loss. In general, bleeding often indicates a worse outcome, and blood loss may result in death. People are often in a coma near the end of life.
Those who survive often have ongoing muscular and joint pain, liver inflammation, decreased hearing, and may have continued feelings of tiredness, continued weakness, decreased appetite, and difficulty returning to pre-illness weight.Problems with vision may develop
Additionally they develop antibodies against Ebola that last at least 10 years, but it is unclear if they are immune to repeated infections
Recovery from Ebola depends on good supportive care and the patient’s immune response. People who recover from Ebola infection develop antibodies that last for at least 10 years, possibly longer. It is not known if people who recover are immune for life or if they can become infected with a different species of Ebola. Some people who have recovered from Ebola have developed long-term complications, such as joint and vision problems.
Even after recovery, Ebola might be found in some body fluids, including semen. The time it takes for Ebola to leave the semen is different for each man. For some men who survived Ebola, the virus left their semen in three months. For other men, the virus did not leave their semen for more than nine months. Based on the results from limited studies conducted to date, it appears that the amount of virus decreases over time and eventually leaves the semen.
WHO aims to prevent Ebola outbreaks by maintaining surveillance for Ebola virus disease and supporting at-risk countries to developed preparedness plans. The document provides overall guidance for control of Ebola and Marburg virus outbreaks:
Ebola and Marburg virus disease epidemics: preparedness, alert, control, and evaluation
When an outbreak is detected WHO responds by supporting surveillance, community engagement, case management, laboratory services, contact tracing, infection control, logistical support and training and assistance with safe burial practices.