Q: What is Ebola?
Ebola is also the short name for the disease Ebola viruses cause. You will see the disease called Ebola virus disease, EVD or just Ebola.
Ebola (the disease) used to be called a viral hemorrhagic fever or VHF. But the World Health Organization and other expert groups are moving away from the use of that term to describe Ebola disease because not everyone who contracts Ebola experiences the visible hemorrhaging – profuse bleeding – that led to that term.
Q: Who discovered Ebola?
Three scientific teams are credited with the discovery: the Institut de Médecine Tropicale Prince Leopold and the University of Antwerp, Belgium; the Microbiological Research Establishment in Porton Down, Salisbury, England and the U.S. Center for Disease Control – now the Centers for Disease Control and Prevention — in Atlanta, Georgia, USA.
The teams at Antwerp and Porton Down identified that blood from an early victim in Zaire (now the Democratic Republic of the Congo) contained filoviruses; the CDC team did the work to confirm that this was not Marburg (a filovirus discovered in 1967) but a brand new virus. You can see the announcement of the first 2 Ebola outbreaks (which occurred almost simultaneously) on page 327 of the World Health Organization’s Weekly Epidemiological Record for Oct. 15, 1976.
The three groups each published a report of their findings in the March 12, 1977 issue of The Lancet. There were 15 authors on the three papers. A number of those scientists and others from the United States, Belgium, Zaire, France and South Africa were involved in the investigation into the first known Ebola outbreak. This larger group became known as the International Commission for the Investigation and Control of Ebola Hemorrhagic Fever in Zaire.
Q: How did Ebola get its name?
The CDC team explained the choice of the name of the new virus in their March 1977 Lancet article: “In deference to the countries involved and to the lack of specific knowledge of the original natural source of the virus, it is also suggested that no names of countries or specific towns be used.”
Q: What is a filovirus?
Q: Is there one type of Ebola, or many?
The different types of virus have different characteristics. For example, while it is known that a few people have been infected with the Reston virus, it does not appear to make humans sick. It does infect and kill primates, however.
The other four known strains do infect humans. However, the Tai Forest strain has only been seen once, in 1994. A scientist who as doing and autopsy of a dead chimpanzee in Cote d’Ivoire’s Tai Forest became infected. He was very sick, but he survived.
Ebola Zaire is the deadliest of the viruses, sometimes killing as many as 90 per cent of people it infects. It is the virus responsible for the massive West African outbreak that began in late 2013.
The strains that have caused the most outbreaks are Ebola Zaire and Ebola Sudan.
The remaining type is called Bundibugyo, because it was first seen in the Bundibugyo District of western Uganda.
Q: What is the natural habitat or reservoir of these viruses?
It could be that outbreaks begin when a person comes in contact with an infected bat. Some outbreaks have occurred among workers who mine in caves infested with bats. And two tourists – an American woman and a woman from the Netherlands – became infected with the Marburg virus while visiting a cave in Uganda where bat colonies live.
Scientists think that sometimes bats infect monkeys or other primates and then people who butcher those monkeys to prepare them to be eaten become infected. The Ebola Zaire outbreak in the Democratic Republic of the Congo in the summer of 2014 is believed to have started when a woman butchered some bush meat her husband had found in the forest.
Once the virus has crossed from an animal to a human, there is a risk that that person will spread the virus to other people, causing a human outbreak. But that doesn’t always happen.
Q: The West African epidemic is described as the largest in history, far larger than earlier outbreaks. What was a typical size of Ebola outbreak before 2014?
Q: Which countries have had outbreaks?
Other than the single case in the Tai forest in Ivory Coast, Ebola had not been seen in West Africa before 2014.
Several other countries have had “imported” cases, which means that a patient from a country with an outbreak traveled elsewhere. For instance, South Africa had an imported case in an infected traveller from Gabon in 1996; he infected a nurse who cared for him. There were also a few Ebola cases stemming from lab accidents; these happened in Britain in 1976 and in Russia in 1996 and 2004.
The 2014 outbreak actually started in December of 2013, but it was not recognized until March 2014. It began in Guinea and spread to Sierra Leone and Liberia. This was the first time Ebola has triggered a major human outbreak outside of its previous known territory.
The West African epidemic has brought Ebola to many more countries. From the three outbreak countries, patients traveled or were evacuated to Nigeria, Senegal, Mali, the United States, Spain, Germany, the Netherlands, the United Kingdom and other places. In some cases, they triggered new, local outbreaks that were eventually contained. Twenty people were infected in Nigeria, for instance, and eight in Mali. A nurse in Madrid who cared for a Spanish missionary who was infected in Sierra Leone also contracted the disease, as did two nurses in Dallas, Texas, who came into contact with a patient who traveled to the U.S. from Liberia.
Q: Ebola Reston is different. Where does it come from?
Q: How does Ebola spread from person to person?
Burial practices that involve cleaning and kissing the corpses of the deceased are known to permit spread of the virus; they often play a significant role in the spread of the virus.
Q: How are Ebola outbreaks contained?
1) Identify and isolate people who are infected.
2) Identify and monitor the contacts of Ebola patients, so that you can isolate them if they develop the disease.
3) Bury bodies safely. Close contact with the bodies of people who have died of Ebola can spread the disease.
Q: What are Ebola’s symptoms?
Q: How long does it take for people to develop symptoms once they contract the virus?
Q: In the 2014 outbreak it took three months before authorities in Guinea realized they had an Ebola outbreak on their hands. And it is said Ebola can be difficult to diagnose. Why?
Q: How do labs test for Ebola?
The timing of a test is important. In the early stage of infection a blood test can actually come back negative. Retesting is recommended in patients who are strongly suspected of having Ebola but whose first test is negative.
Sometimes scientists test people to see if they have been infected in the past. Again, they test blood samples to look for antibodies to the virus.
Q: What treatments are available for Ebola? Do drugs or vaccines exist?
There are a number of experimental vaccines that are being developed and tested. Tests in primates show these vaccines can prevent infection; the human studies needed to prove this are now taking place in West Africa. The epidemic in West Africa has led to a huge acceleration of drug and vaccine development.
For more on this topic, see the chapter entitled Drugs, Vaccines & Diagnostics.
Q: If there are no drugs or vaccines, how are people with EVD treated?
When patients become too sick, however, they may not be able to drink the volume of fluids they need. Ebola patients treated in Europe and the United States have also received intravenous (IV) fluids – fluids dripped into their veins as a standard part of their care. Some experts – including Dr. Paul Farmer of the U.S. aid group Partners in Health – have been critical of the fact that IV fluids haven’t been available to all patients in Africa.
But others say that during the height of the outbreak, when treatment centers were turning away patients because they were full, there were not enough medical staff to give patients IV fluids. Also, delirious patients sometimes rip the IV needles out of their arms and bleed from the entry point.
Q: Why does Ebola frighten people so much?
As well, the illness can cause great suffering, with lots of vomiting, diarrhea and sometimes bringing up blood or profuse nose bleeds. That puts people caring for Ebola patients at high risk of becoming infected. Health-care workers often make up a significant percentage of the Ebola cases in outbreaks.
The bestseller The Hot Zone: A Terrifying True Story may also have contributed to the fear surrounding Ebola. The book, which described patients’ symptoms in grisly detail–including the “liquefying” of organs–has been criticized as sensationalist; its author, Richard Preston, has said he wants to paint a more accurate picture of the disease in an updated version of the book.