Myths and Facts: Ebola

It’s being called the “deadliest Ebola outbreak in history.” As of this writing, more than 14,000 people have become infected with the virus that began in four countries in West Africa, and more than 5,000 have died.¹ In August, experts at the World Health Organization (WHO) declared the Ebola epidemic an international health emergency requiring a coordinated global approach. It is a highly-infectious disease that, since November 2013, has been spreading within and, now, beyond the borders of West Africa. And, without additional interventions or changes in community behavior, the Centers for Disease Control and Prevention (CDC) estimated that the number of Ebola cases could rise to as many as 1.4 million in January.² But, spreading even more quickly than the virus itself is fear due to a lack of understanding about what causes Ebola and how it is spread — making the situation even more difficult to contain.

Separating Myth from Fact

MYTH: All Ebola viruses are the same.

FACT: Ebola is one of five viruses that cause viral hemorrhagic fever, which takes over cells and replicates quickly, in turn “shutting down and misdirecting parts of the immune system and sending the rest into hyperdrive.”³ Four of the Ebola viruses can cause severe illness in humans and animals, and one causes illness in some animals but not in humans.⁴ The five species of Ebola virus include Zaire, Bundibugyo, Sudan, Reston and Tai Forest, the first three of which have been associated with large outbreaks in Africa. The current virus in West Africa belongs to the Zaire species.⁵

MYTH: This outbreak of Ebola is just like previous outbreaks.

FACT: The Ebola virus first appeared in 1976 in two simultaneous outbreaks, one in southern Sudan (now South Sudan) and the other in northern Zaire (now the Democratic Republic of Congo) in a village near the Ebola River, after which it was named.⁵ Prior to the current outbreak, there were 33 previous outbreaks of various Ebola viruses, all of which were contained and stopped in West Africa with far smaller death tolls than this one.⁶ The current outbreak is the largest and most complex with more cases and deaths than all other outbreaks combined. It surfaced in late 2013 in Guinea in the rain forest close to the borders with Liberia and Sierra Leone.³ And, it is spreading across land and air borders not just in West Africa,⁵ but across continents, with the first reported case of Ebola diagnosed in the U.S. in September.⁷ In October, the first transmission case outside of West Africa occurred in Spain when a nurse contracted the deadly virus after caring for a sick priest who had been flown back from West Africa for treatment.⁸

MYTH: Ebola is a highly contagious disease.

FACT: While Ebola is extremely infectious, it is only moderately contagious. It is infectious because an infinitesimal amount can cause illness, and lab experiments show that even a single virus could cause a fatal infection. However, Ebola is not highly contagious because it is not a respiratory disease — one that can be transmitted through the air such as influenza or measles. In fact, because the Ebola virus doesn’t travel far through the air like respiratory viruses, even sitting several rows away from an infectious person on a plane or in a room wouldn’t put one at risk of transmission.⁴ Ebola is also not a food-borne or waterborne illness, so it can’t be transmitted through food or water.⁹

Ebola is introduced into humans through close contact with blood, secretions, organs or other bodily fluids of infected animals such as chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead or in the rain forest. No one is sure when the current virus was first transmitted to humans or from what species, but it is thought to be a fruit bat.³ The virus then spreads through human-to-human transmission via direct contact (through broken skin or mucous membranes) with body fluids from an infected person, from objects (needles, sheets, clothing, etc.) contaminated by an infected person, as well as from direct contact with the body of a person who has died from Ebola. In West Africa, local customs concerning handling the dead have led to further infections. For some West Africans, the final farewell, one of the most important days of one’s life, is a “hands-on, affectionate ritual in which the body is washed and dressed and, in some villages, carried through the community, where friends and relatives will share a favorite beverage by putting the cup to the lips of the deceased before taking a drink.”³

For those who survive, Ebola remains infectious in them as long as their blood and body fluids, including semen and breast milk, contain the virus. For instance, men who have recovered from Ebola can still transmit the virus through their semen for up to seven weeks after recovery.^5,6

MYTH: Individuals who are not symptomatic for Ebola are still contagious.

FACT: Unlike measles or influenza, Ebola can’t be transmitted until individuals present with symptoms. While symptoms typically appear between eight and 10 days after exposure to the virus, the actual incubation period — the time from virus infection to onset of symptoms — can span from two to 21 days. Initial symptoms of Ebola include the sudden onset of fever, fatigue, muscle pain, headache and sore throat. These are followed by vomiting, diarrhea, rash, symptoms of impaired kidney and liver function and, in some cases, both internal and external bleeding (e.g., oozing from the gums and blood in the stools).⁵ Death can come within days from multiple organ failure.³ 

MYTH: Ebola is easy to diagnose because those with the disease hemorrhage blood.

FACT: One of the more recognizable symptoms of Ebola is bleeding, but it doesn’t always occur. That’s what makes Ebola difficult to diagnose initially because in its early stages, it looks like the flu. One study found external bleeding in only 41 percent of cases.

When bleeding does occur, usually in the late stages of the disease, it happens in small amounts, and those who bleed aren’t more likely to die than those who don’t. Bleeding can occur externally from the eyes, nose, ears, mouth, rectum or at puncture sites such as from an IV, or it can occur internally.⁶

Ebola is diagnosed through an antibody-capture enzyme-linked immunosorbent assay (ELISA), antigen-capture detection tests, a serum naturalization test, a reverse transcriptase polymerase chain reaction (RT-PCR) assay, electron microscopy and virus isolation by cell culture. Lab findings include low white blood cell and platelet counts and elevated liver enzymes.⁵

MYTH: The spread of this Ebola outbreak can’t be stopped.

FACT:While there is serious concern about the spread of this Ebola outbreak, in previous outbreaks, health officials have successfully stopped the disease from spreading by finding patients, isolating them, finding everyone those original patients have contacted and keeping the patients isolated until they’re no longer a threat.⁶

However, there are many unique challenges to this particular outbreak. First, it wasn’t until March — almost six months after the first case — that Ebola was identified as the disease in West Africa, at which time 49 cases, including 29 deaths (a case fatality ratio of 59 percent) had been reported. Second, the affected regions have impoverished healthcare infrastructures and a deep distrust of government, making it difficult for healthcare workers to carry out public health campaigns.³ Last, the international response was delayed, giving the disease time to spread.⁶

However, in September, some scientists predicted that the outbreak would last another 12 to 18 months, which means it is expected to be contained. And, it should be noted that compared with other infectious diseases, Ebola is spreading much slower, with those infected transmitting the virus to only one or two other people on average, while each case of measles transmits to an average of 17 other people.⁶ Yet, to slow the spread of Ebola and eventually stop it, the disease will need to be transmitted to fewer than one person.³

MYTH: Ebola is a more dangerous virus than any other.

FACT:While Ebola has one of the highest death rates among infectious diseases, it kills far fewer people than many other diseases because it’s not as contagious. For instance, an estimated 1.6 million people worldwide died of HIV and AIDS-related causes in 2012, according to WHO. CDC puts the average number of annual deaths from seasonal influenza in the United States somewhere between 3,000 and 49,000. CDC and WHO estimate that more than 600,000 people die each year worldwide from malaria. And, CDC reports an estimated 440,000 children who contract rotavirus die each year from complications, namely dehydration.¹⁰

MYTH: Ebola is a death sentence.

FACT: Not everyone dies from Ebola. Throughout the history of Ebola outbreaks, the case fatality rate has hovered around 50 percent. As of this writing, the current outbreak has a case fatality rate of 53 percent.11 Unfortunately, there is also no U.S. Food and Drug Administration-approved vaccine to prevent or drug to cure Ebola, either, although vaccines are in development and experimental drugs are being used to treat some patients. Currently, the standard treatment for Ebola remains supportive care, including balancing the patients’ fluids with electrolytes, maintaining their oxygen status and blood pressure and treating them for any complicating infections.¹²

Researchers are working toward developing drugs to treat Ebola. One is ZMapp, developed by Mapp Biopharmaceutical Inc., a combination of three different monoclonal antibodies that bind to the protein of the Ebola virus. While ZMapp hasn’t been tested in humans for safety or effectiveness, it has shown 100 percent effectiveness in 18 rhesus monkeys infected with Ebola.^12,13 At the time of this writing, very few doses of the drug had been manufactured, all of which had been distributed, including to two African doctors, a Spanish priest, who later died, and two U.S. aid workers, who recovered.¹⁴

Two doses of another experimental drug were given to the first patient diagnosed with Ebola in the U.S., who later died. Brincidofovir is an unapproved oral antiviral drug produced by Chimerix. Phase 3 clinical trials of the drug are being conducted to treat cytomegalovirus and adenovirus infections, and a Phase 1 clinical trial as a therapy for Ebola was expected to begin at the end of 2014.¹⁵

Finally, the National Institute of Allergy and Infectious Diseases (NIAID) has awarded $2.4 million to BioCryst Pharmaceuticals to test its experimental broad-spectrum antiviral called BCX4430 in monkeys. BCX4430 has already been successfully tested in monkeys for the treatment of Marburg.¹⁶

MYTH: Ebola can’t be prevented because attempts at developing a vaccine to date have been unsuccessful.

FACT: An Ebola vaccine may soon be reality. The National Institutes of Health (NIH) is partnering with several parties to develop an Ebola vaccine. Initial human testing of an investigational vaccine co-developed by NIAID and GlaxoSmithKline (GSK) to prevent Ebola began in September.¹² Containing no infectious Ebola virus materials, this vaccine is a chimpanzee adenovirus vector vaccine into which Ebola genes have been inserted. This gene inserts express a protein to which the body makes an immune response. Recently, it showed promise in a primate model.17 NIH has also partnered with a British-based international consortium to test the NIAID/GSK vaccine in healthy volunteers in the United Kingdom and in the West African countries of Gambia and Mali.¹²

NIH is also supporting Crucell’s development of a multivalent Ebola/Marburg vaccine using recombinant adenovirus vector platforms and Profectus BioSciences’s development of a recombinant vesicular stomatitis virus vectored Ebola vaccine. Additionally, NIH and the Thomas Jefferson University are collaborating to develop a candidate Ebola vaccine based on the established rabies vaccine.^12,17

There also are other companies developing Ebola vaccines. With funds from the Department of Defense’s Defense Threat Reduction Agency, Tekmira and Biocryst Pharmaceuticals have therapeutic candidates for Ebola in early development. The Department of Defense is also working with Newlink to develop an Ebola vaccine candidate.¹² In October, Protein Sciences announced it had been developing an Ebola vaccine with plans to deliver test samples to NIH in December.¹⁸ And, last, Thailand’s Siriraj Hospital claims it has developed a vaccine for Ebola.¹⁹

Dispelling the Myths Now

The only cure for Ebola right now is time. WHO released a plan to stop Ebola with a price tag of $490 million, which continues to increase as the outbreak progresses. Most of the funds will go to building treatment centers, hiring more staff and providing safe burials for victims in Sierra Leone, Liberia and Guinea — the three countries with the most infections.²⁰ In response, governments across the world have pitched in to help stop the outbreak.

In the U.S., efforts are being made to stop the virus from entering the country and to put plans in place for how to protect against it when it does. In October, airports in the U.S. began taking the temperatures of arriving passengers whose flight itineraries originated in West African countries.²¹ Also in October, the American Association for Accreditation of Ambulatory Surgery Facilities began providing outpatient facilities with a preparedness checklist for Ebola, as well as facts about the virus.²² And, the Centers for Disease Control and Prevention has posted a special Web page that offers physicians the resources needed to be prepared for patients who might have the disease at www.cdc.gov/vhf/ebola/hcp/index.html.

Rapid progress is being made in the development of a drug to treat Ebola and a vaccine to protect against it. Until then, the only real way of curbing the fear about this frightening disease is to separate the myths from the facts.¹