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What You Need to Know about Ebola Virus Disease

Renee Despres
Monday, February 20, 2017 - 05:22Healthcare workers being trained in use of personal protective equipment during Ebola epidemic

In March 2014, a few public health officials and virologists expressed concern as 49 cases of Ebola disease were diagnosed in Guinea, a poor, heavily populated nation in West Africa. They were right to be concerned. Those 49 cases would spread – slowly at first, then exponentially – into the first Ebola epidemic the world has ever seen, causing widespread illness in Guinea, Liberia, Nigerian, Senegal, and Sierra Leone. Meanwhile, health-care workers in the United States and Spain contracted the disease while treating patients who had contracted the disease in Liberia. By October 15, 2014, the World Health Organization (WHO) was reporting a total of 8997 Ebola cases in West Africa, with nearly 4493 deaths. Those numbers, experts cautioned, probably represent less than half of the true impact of the disease. Meanwhile, the U.S. Centers for Disease Control and Prevention (CDC) warned that if the virus continues to spread at its current pace, more than 1.4 million people would fall ill, and up to 900,000 would die, by January 2015.

Meanwhile, a second, unrelated Ebola outbreak occurred in the Democratic Republic of the Congo – ironically, the place where the Ebola virus was first identified. According to the WHO report, 68 people had fallen sick in this outbreak, and 49 people had died, including 8 health-care workers, as of October 15.

With the spread of Ebola disease, concerns and questions about the disease have spread far beyond that initial handful of public health officials to the general public. Media coverage of the disease hit a frenzied note with the first diagnosis of an imported case in the United States on September 30th. But amidst all the hype and fear, there are a few things that everyone should know about the Ebola epidemic, why it's spiraled out of control, and what the real risks are and are not.

Here's what you need to know about the Ebola virus disease.

What is Ebola disease?

Ebola disease – or more accurately, Ebola hemorrhagic disease – is a severe, often deadly condition. It is one of several diseases that are marked by internal bleeding and fever, called hemorrhagic fever diseases. As many as 50-90% of people who develop Ebola disease die.

In the current outbreak, about 70% of people who have contracted the disease are thought to have died. Experts aren’t sure of the exact numbers, because public health surveillance systems in the countries that are most affected are weak – and further weakened by the impact of the disease on health-care workers in those countries.

What causes Ebola disease?

Ebola disease is caused by the Ebolavirus, a member of the family Filovinidae. Five subspecies of Ebolavirus have been identified. Four of these subspecies have caused disease in people; the fifth, Reston virus, has sickened monkeys and other non-human primates, but not people.

The other four Ebolavirus subspecies are all named based on the places where they were first identified:

  • Ebola virus (Zaire ebolavirus)
  • Sudan virus (Sudan ebolavirus)
  • Taï Forest virus (Taï Forest ebolavirus, previously called the Côte d’Ivoire ebolavirus)
  • Bundibugyo virus (Bundibugyo ebolavirus)

The current outbreak in West Africa is caused by the Zaire ebolavirus. Previous outbreaks of this subtype have killed up to 90% of those infected, making it the deadliest strain of ebolavirus.

Like other viruses, the Ebolavirus mutates (changes its genetic makeup) quickly, making it possible for new strains to appear.

What are the signs and symptoms of Ebola disease?

Most people with Ebola disease have the following symptoms:

  • Fever
  • Headache
  • Joint and muscle aches
  • Weakness
  • Diarrhea
  • Vomiting
  • Stomach Pain
  • Lack of appetite (anorexia)

In some people, Ebola may cause:

  • A rash
  • Red eyes
  • Hiccups
  • Cough
  • Sore throat
  • Chest pain
  • Difficulty breathing
  • Difficulty swallowing
  • Bleeding inside and outside of the body

Most commonly, signs and symptoms of Ebola disease appear from 8 to 10 days after someone has been exposed to the virus. However, some people have become sick within 2 days of exposure; in other cases, it has taken 21 days for people to develop symptoms. This long incubation period has contributed to the disease’s rapid spread, as people may be infected for up to three weeks before showing any symptoms.

When they do appear, symptoms usually come on suddenly. Early symptoms such as rash, fever, and cough may mimic many other common diseases, including flu, the common cold, or skin infections.

Can Ebola disease be treated?

There is no treatment for Ebola disease. However, people are more likely to survive if they receive early, high-quality supportive care, including rehydration and treatment to help control symptoms. In the hospital, patients are usually rehydrated using an “IV” or intravenous catheter that allows fluid and medications to be put directly into the vein, given pure oxygen to help with breathing, and given medications to help control pain, nausea, and other symptoms.

Why do some people die and others survive?

Experts do not know why some people are able to survive Ebolavirus disease, but some think that early supportive care may help the person survive long enough to develop some immunity from the disease. People with weakened immune systems because of poor nutrition, disease, or other stressors are thought to be more susceptible.

How is Ebola disease passed from person to person?

Most research suggests that you cannot contract Ebola from a person who does not have symptoms of the disease. The Ebola virus passes from person to person through bodily fluids, including sweat, tears, blood, vomit, urine, semen, and breast milk. The virus is found in bedding, clothing, on doorknobs, handles, and anything else the person touches.

The virus has been found in a man’s semen for up to 82 days (3 1/2 months) after he has recovered from the virus. Likewise, women can pass the virus to their children through breastmilk after recovery. Experts are not certain how long the virus can survive in breastmilk, so they recommend that women do not breastfeed for at least several weeks after recovering from Ebola disease.

The virus does not spread from person to person through the air, like the flu or other respiratory diseases. However, it could spread through droplets – for instance, if person with symptoms of Ebola coughed directly on someone, expelling saliva, mucus, or blood and that saliva, mucus, or blood touches the person’s eyes, mouth, nose, or broken skin. This mode of transmission is thought to be very rare, generally only affecting health-care workers.

Who is most at risk?

Informal caregivers – mostly women who are caring for loved ones in their homes – are at greatest risk, for they have no training or protective equipment and are exposed to the person’s bodily fluids. Aid groups have put together “health kits” that include gloves, masks, rehydration fluids, and chlorine for disinfection; these kits are expected to help somewhat, but they are not adequate substitutes for care in a hospital isolation unit.

Professional and volunteer healthcare workers are also being deeply and tragically affected by Ebola disease. As of the October 15 WHO report, 427 healthcare workers had fallen ill with Ebola virus disease, and 236 had died. In addition to the tragedy of the loss of their lives in service to others, the loss of health-care workers has devastated the already fragile medical and public health systems in these countries. That fragility has contributed to their deaths, for many hospitals have been operating with little personal protective equipment such as gloves, facemasks, and gowns.

Burial teams are also at great risk, because the body of a person who has died of Ebola disease is filled with the virus, which scientists refer to as a “high viral load.” The virus can live for several days in body fluids, including blood. Dying – especially from Ebola disease – usually involves a lot of bodily secretions. So when family members wash the body of an Ebola in a funeral ritual, or even touch the body, they are exposed to the virus.

If someone becomes infected but survives, can that person infect another person?

Generally, Ebola survivors are not thought to be contagious after two days without signs and symptoms of the disease. According to the CDC, "Individuals who recover from Ebola are not contagious as far as transmitting the virus through close personal contact with blood or body fluids such as urine, feces, sweat, or vomit."

After symptoms of Ebola disease resolve, the acute phase of the infection – when the person is shedding the greatest amount of the virus – is thought to be over. However, there’s some evidence that the patient may continue to shed the virus even after acute infection subsides. The time it takes to completely clear the virus appears to vary from person to person, just as the time it takes for an exposed person to fall ill varies between 2 and 21 days. Men have been shown to carry the virus in their semen for up to 7 weeks after recovering, and women may carry it in breastmilk for several weeks.

Doctors use blood test results to determine if the person is still infected. They look for the amount of virus in the blood (the viral load) and the presence of antibodies – proteins in the blood that show the person is fighting off the infection. Case studies of Ebola survivors in West Africa also indicate that Ebola survivors cannot pass the virus to others once it is no longer detectable in their blood.

After having had Ebola virus disease, the person is thought to be immune to the particular strain of the virus that sickened him or her, although experts are not sure how long that immunity lasts.

Where did Ebola disease come from?

Ebola is a zoonotic virus, meaning it normally lives in animals in the wild. Although scientists are not certain exactly what animals harbor the virus, most evidence points toward fruit bats as its “natural reservoir.” Fruit bats are often eaten as a delicacy in West Africa. Non-human primates, including monkeys, chimpanzees, and gorillas, can also harbor the virus.

The Ebola outbreak in West Africa is thought to have started when a 2-year-old toddler in Guinea became infected after having contact with an infected bat.

What is different about the current Ebola disease outbreak?

The Ebola virus was first discovered in 1976, when an outbreak 318 people suddenly fell ill in the Democratic Republic of Congo. Nearly all (88%) of the people who fell ill in that outbreak died. Previous outbreaks have been contained to a few hundred people, primarily because they have occurred in extremely rural areas. Few people traveled in and out of those areas.

In contrast, the 2014 epidemic started in Guinea, close to international borders, in a region that had never seen the virus before. The most severely affected countries – Guinea, Sierra Leone, and Liberia – have fragile to virtually non-existent health systems. In the areas that have been hardest hit, sanitation and other infrastructure is weak. Low literacy rates and suspicions of health-care workers make it difficult to get information out about Ebola disease. Extreme poverty extends to the limited health-care facilities in the region, where gloves, gowns, masks, and other protective equipment are in scarce supply.

All of these factors are contributing to the rapid spread of the disease. Epidemiologists are now using the term “epidemic” to describe the spread of Ebola disease in West Africa – a term that means a disease is spreading widely throughout a region. There has never been an Ebola epidemic before; only outbreaks.

In addition, the slow response of the international community has allowed the virus to spread. Although the then-outbreak began in March, the World Health Organization (WHO) didn't declare the rapid spread of Ebola disease a Public Health Emergency of International Concern (PHEIC) until August 8. Notably, this is only the second time the WHO has ever invoked this power. Still, the international community didn't truly start mobilizing until mid-September. On September 16, U.S. President Barak Obama committed 3,000 troops and other resources to stopping the epidemic. On September 18, the United Nations (UN) Security Council today unanimously adopted a resolution to create a special mission to coordinate global resources flowing to Ebola-stricken countries. Until then, the response was left largely to non-governmental organizations such as Medecins sans Frontiers. Despite admirable work, they were overwhelmed.

The disease continues to spread rapidly in West Africa. For every one person who's infected, about two more people a getting sick. So one person passes it to two other people, those two people pass it to four other people, four sick people turn into 16 sick people... you get the picture.

How Widely Will Ebola Spread?

On September 30, 2014, the first imported case of Ebola disease was diagnosed in the US. Thomas Eric Duncan, a Liberian citizen, flew to the United States from Liberia and arrived on September 20. He was not sick during his 28 hours of travel, so there’s no way he could have passed the virus on to others on the planes or in the airports he visited. But on September 26 he visited the emergency department at Texas Presbyterian Health Hospital in Dallas, Texas. Although he told the triage nurse that he had recently come from Liberia, he was evaluated and sent away with an antibiotic. By September 28, Duncan had become more ill. He returned to the emergency department at Texas Presbyterian by ambulance, this time to be diagnosed with Ebola disease and placed in isolation. Duncan died on October 8.

Four days later, on October 12, one of the nurses who had treated him, 26-year-old Nina Pham, was diagnosed with Ebola. And on October 15, another nurse who had treated Duncan, 29-year-old Amber Vinson, was diagnosed with Ebola. Their cases have prompted the CDC to revise their infection control recommendations, adding increased requirements for personal protective equipment (PPE).

Although theses case are worrisome, experts agree that with isolation procedures, strong surveillance, and the ability to track contacts, it is highly unlikely that Ebola will spread rapidly throughout the US.

Before Duncan's diagnosis, the US and other countries outside of Africa had treated several Ebola patients. All of the previous patients had been diagnosed in West Africa. They were flown in special aircraft, with strict isolation procedures, and immediately transferred to isolation wards for treatment. In contrast, Duncan may have had contact with as many at 100 people, including 5 schoolchildren, while he was symptomatic. CDC experts continue to trace all of his contacts, using a procedure called contact tracing.

For the majority of people in the US and other developed countries with robust health systems, officials say there’s little to worry about. The CDC has issued several guidance documents for health-care workers about taking extra precautions to protect themselves and asking patients routinely about their recent travel history. Health-care workers are advised to take extra precautions when faced with a patient with flu-like symptoms. Officials continue to rethink this guidance and investigate transmission, especially in light of Pham and Vincent contracting Ebola virus disease.

More cases of imported disease can be expected in the US and other developed countries, though, and public health and medical systems need to practice vigilance, altering procedures so that anybody who goes to a clinic or emergency room with flu-like symptoms is asked about their recent travel history, especially to West Africa.

How Can I Protect Myself?

If you live in or are traveling to an affected country in West Africa, take all possible precautions. The CDC recommends taking the following steps to protect yourself:

  • Practice careful hygiene. Avoid contact with blood and body fluids.
  • Do not handle items that may have come in contact with an infected person’s blood or body fluids.
  • Avoid funeral or burial rituals that require handling the body of someone who has died from Ebola.
  • Avoid contact with bats and nonhuman primates or blood, fluids, and raw meat prepared from these animals
  • Avoid hospitals where Ebola patients are being treated
  • If you are a traveler, monitor your health for 21 days after you return and seek medical care immediately if you develop symptoms of Ebola.

No matter where you live:  

  • Wash hands frequently and thoroughly, for at least 20 seconds using warm, soapy water. If soap and water are not available, use an alcohol-based hand sanitizer.
  • Don’t put your hands in your eyes, mouth, or nose (and teach children to do the same)
  • Cover all wounds, including scratches and nicks.
  • Disinfect surfaces with a chlorine-based bleach solution, especially if someone has been ill
  • Cover coughs and sneezes
  • Go to a health facility if you have headache, fever, pain, diarrhea, red eyes, rash, and vomiting


Image credits: Benjamin Park, Centers for Disease Control and Prevention.