Ebola Virus Disease
The Ebola virus disease (EVD), previously referred to as Ebola hemorrhagic fever, is a severe and often fatal infection. It is spread through contact with infected blood or bodily fluids.
Ebola virus disease was first identified in 1976 in Sudan and the Democratic Republic of the Congo (formerly Zaire). It is named after a river in the Democratic Republic of the Congo. Since its discovery, there have been several Ebola outbreaks, primarily limited to remote villages near tropical rainforests in Central and West Africa. As a result of the remoteness of the locations in which most of the outbreaks have occurred, the number of victims has been limited. The 2014 outbreak of Ebola virus disease has been one of the largest in documented history, in terms of both the number of cases and the geographical spread.
There have been 5 identified species of the ebolavirus genus, with 3 of them having caused previous EVD outbreaks. The 2014 outbreak is caused by the Zaire species, the most deadly strain, with a historic fatality rate of up to 90%.
Ebola outbreaks occur when the virus is transmitted first from an infected animal to a human and then between humans. The viral infection is spread from animals to humans through contact with infected wildlife such as fruit bats, chimps, and gorillas. Certain fruit bats are believed to be the natural hosts for the Ebola viruses.
EVD is transmitted from person to person by direct contact (through broken skin and mucous membrane) via bodily fluids or secretions from infected people, such as:
- breast milk
- semen (up to 61 days after infection)
Transmission can also occur through contact with objects contaminated with these fluids and the bodies of the deceased with EVD. Since the bodies of the deceased can infect those who handle them, safe burial practices are extremely important in containing outbreaks. The infection can be spread further by cultural burial practices such as ritual washings that bring people into close contact with infected bodies.
Symptoms and Complications
The Ebola virus targets the host's (infected person's) blood and immune system, which can lead to bleeding and a weakened immune system. After an incubation period (time between infection and the appearance of symptoms) of 2 to 21 days, EVD is characterized by a rapid onset of flu-like symptoms such as:
- muscle pains
- sore throat
From there, many patients go on to develop:
- measles-like rash
- reduced liver and kidney function
30% to 50% of cases result in internal and external bleeding 4 to 5 days after the onset of symptoms. Although some people die as a result of shock due to multiple organ failures, most Ebola victims die as a result of severe dehydration from extensive vomiting and diarrhea.
During outbreaks, those at greatest risk of getting the viral infection are health care workers and the family and friends of the infected who have close contact with the patients.
Making the Diagnosis
Due to the fact that most Ebola infection symptoms such as weakness, fever, headache, and muscle pains are not specific to the disease, more common diseases need to be ruled out first, especially during the early stages of the infection when diagnosis is difficult to make. Common diseases with similar symptoms include malaria, typhoid fever, and cholera. Your doctor will ask about your travel history and your medical history, with particular interest in whether you've been in contact with possible infected individuals or animals. People with suspected EVD should be quarantined while waiting for definitive diagnosis by laboratory tests.
There are several laboratory tests that can be used to diagnose Ebola virus disease. In most cases, your doctor will take samples of your blood and urine. These tests detect traces of the virus itself or our bodies' defence response against the virus.
Treatment and Prevention
There is currently no cure for Ebola virus disease, so treatment is mainly supportive and typically involves rehydration, nutrition, and medications to manage symptoms (pain, fever, vomiting, etc.). The majority of people with EVD die from severe dehydration, so early supportive treatment is critical in improving the chances of survival.
Since there is no cure for the disease, the key in limiting outbreaks is to prevent transmission from animals to humans and between humans. There are several measures that need to be in place, including:
- rapid quarantine of suspected infected animals – these animals should then be buried or burned promptly
- handling all animals and their waste with gloves and other protective clothing
- cooking animal products (meat and blood) thoroughly before eating
- safe burial practices
- wearing protective gear such as gloves and other personal protective equipment (such as face protection and long-sleeved gowns) when dealing with infected patients
- safe injection practices
- regular hand washing
- sanitation and sterilization of the environment and instruments
- identification and isolation of infected individuals from the community
- tracing contacts, including those during the incubation period
There are now vaccines available to prevent infection. Although these vaccines have been proven safe and effective, more research is needed before these vaccines become widely available. Currently, they are reserved for those at highest risk during an Ebola outbreak, such as family members and close contacts of an infected person.