Ebola has an average fatality rate above 50%

There have been close to 40 Ebola outbreaks since 1976

Ebola is a rare but deadly virus that causes severe illness, organ damage, and sometimes internal bleeding. It spreads through contact with infected bodily fluids and is most common in parts of sub-Saharan Africa. This explainer covers its symptoms, transmission, and treatment options.

Watch what the Ebola virus does inside the body in order to spread and survive

Once infected, the virus targets the body's immune cells, spreading the infection throughout the body. Patients exhibit severe flu-like symptoms. Ebola then targets the liver, which produces proteins that help blood clot, and the adrenal glands, which control blood pressure. The immune system may overreact to the viral invasion, releasing a cytokine storm that can result in shock, multiple organ failure, and death.

Watch what the Ebola virus does inside our cells and organs in order to spread and survive.

Three Ebola species are responsible for most large outbreaks of the disease

The Ebola Zaire, Sudan, and Bundibugyo species are the three ebolaviruses responsible for most large outbreaks in Africa. Among these, Ebola Zaire is the deadliest, with as many as 90% of cases resulting in death. Ebola Sudan has about a 50% fatality rate and has caused several outbreaks in Uganda. More recently discovered in 2007, Bundibugyo causes death in about 30% of people and has caused two large outbreaks in Uganda and the Democratic Republic of the Congo (DRC) before the spring 2026 DRC outbreak. Taï Forest virus is the rarest and is known to have infected a single person in the Côte d'Ivoire in 1994.

Three Ebola species are responsible for most large outbreaks of the disease, yet the only approved Ebola vaccine is known to work against just one of them.

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

Ebola infects and disables immune cells, triggering a cascade of events that leads to small blood clots throughout the body, weakening blood vessels and interrupting blood flow to key organs.

Marburg virus, related to Ebola, is also extremely deadly

Discovered nine years before Ebola, Marburg is part of the same filovirus family. While this virus is less contagious, it can still be deadly. Currently, no vaccines exist against this disease. (Some users may encounter a paywall.)

Marburg virus, related to Ebola, is also extremely deadly, and has no available vaccine.

Ebola is a filovirus, meaning it resembles a thread under a microscope

Filovirus is derived from the Latin word 'filum', meaning 'thread.' That term describes its thin, flexible, threadlike appearance. Originally isolated in 1976, the microscopic image of the Ebola virus is now famous, even portrayed in the movie Outbreak. In fact, Ebola's threadlike appearance can vary in both length and degree of twisting, sometimes resembling a bowl of spaghetti.

See how Ebola tore through Guinea, Sierra Leone, and Liberia in 2014-2016.

Scientists have struggled to pin down Ebola's natural reservoir species for decades, but the available evidence suggests that it's very likely fruit and insect-eating bats found in Africa.

See how Ebola tore through Guinea, Sierra Leone, and Liberia in 2014-2016

Frontline traced how the outbreak started and spread across West Africa. documenting first-hand accounts and patient experiences. This Ebola outbreak was the deadliest to date, resulting in over 11,000 deaths.

Rabies is nearly 100% fatal once symptoms appear

Rabies, a viral disease attacking the central nervous system, is nearly always fatal once symptoms appear. It spreads through the infected animal saliva (typically through bites) and causes encephalitis, leading to severe neurological symptoms and death. See how the lyssavirus—the bugs behind rabies—work once inside the body.

How the most famous Ebola outbreak book got aspects of the disease so wrong

Richard Preston's 1994 book The Hot Zone brought knowledge of Ebola to the masses. But, beyond the poor portrayals of the science and the scientists, the book fostered fearmongering about Ebola, with portrayals of "liquefying," "dissolving," and "bleeding out." These falsehoods about Ebola have persisted for decades and appear to be reinvigorated with every new emergence of the disease.

The 2026 Ebola outbreak is hampered by a lack of vaccine against the species of the virus, heightening the need for rapid tests to aid in disease control.

Watch how viruses like Ebola can spill over from animals to humans—and vice-versa.

How the most famous Ebola book, The Hot Zone, which sold 3.5 million copies and was translated into 30 languages, got aspects of the disease so wrong.

Bats have evolved to carry viruses without getting sick

Bats—the likely animal reservoir for diseases including Ebola and coronavirus—tolerate viruses without getting sick. The secret lies in evolutionary adaptations allowing bats to become the world’s only flying mammal and to thrive under immense physiological stressors.

An Ebola vaccine was developed during the 2018 west African Ebola outbreak

A study found that Merck's rVSV-ZEBOV Ebola vaccine (called Ervebo) was 84% effective against infection during the 2018-2020 Ebola outbreak in the DRC. This effect was observed for both sexes and among children and adults. The vaccine is approved to help provide protection against one specific species of the Ebola virus. The 2026 Ebola outbreak is with a different species of the virus—not the one that the vaccine is approved to treat.

See the evolution of Ebola vaccine and treatment development.

Explore what it's like Inside a patient isolation unit

Containing a contagious disease like Ebola requires strict protective measures. There are several specialized medical wards to contain deadly infectious diseases at hospitals across the U.S. Emory University has one such unit, where 4 patients were treated during the 2014 outbreak.

Learn how monoclonal antibodies, which mimic the body's antibodies, can fight diseases like Ebola.

Treating black fever can result in a complication that spreads the deadly disease

Black fever, a deadly parasitic disease second only to malaria, threatens more than 1 billion people across more than 83 countries. Also known as kala-azar or visceral leishmaniasis, the disease is caused by parasites that spread through sandfly...

Watch the cumbersome, but necessary, precautions healthcare workers must take to care for and protect themselves while caring for Ebola patients.

Wolbachia: the bacteria that could eliminate dengue fever

Dengue fever, transmitted by mosquitoes, kills more people annually than all types of natural disasters combined. However, mosquitoes that host Wolbachia bacterium have their ability to transmit the virus naturally suppressed, offering a route to eliminating nearly 25,000 deaths annually.

Variola: the second-deadliest virus on Earth

Because it was declared eradicated in 1980, many forget smallpox is one of history's deadliest diseases—in its final century, it's estimated to have claimed 500 million lives. This 11-minute video from production studio Kurzgesagt takes a look at...

Most cases of West Nile virus are asymptomatic in people

About 1 in 5 infected people develop symptoms from West Nile, including symptoms such as fatigue, head and body aches, and vomiting. But around 1% of patients develop severe complications such as encephalitis or meningitis, which can be life-threatening. Those who are most likely to become severely ill are people over age 60.

Cultural norms about how to handle the bodies of loved ones in communities in West Africa have hampered Ebola responses.

Children under 5 account for 76% of all malaria deaths in Africa

The main hypothesis for why the disease hits this age group the hardest is that children this young have still-developing immune systems. Pregnant women and people with HIV/AIDS are also at higher risk of severe infection.

Measles symptoms range from fever to pneumonia and encephalitis

While less common, most measles-related deaths come from secondary conditions such as pneumonia (one to six cases per 100 patients) and encephalitis (one case per 1,000 patients). Blindness, which is rare, may arise from corneal ulceration.

About 20% of people infected with cholera have severe symptoms

That's according to studies from outbreaks in Bangladesh. Most people who contract the disease have mild or moderate symptoms, or none at all. Yet anyone infected with the disease-causing bacteria can shed the pathogens in their feces for a few days, or even up to around 10, seeding the environment with bacteria.

HFMD symptoms typically begin to show up 3-6 days after exposure

Fever is often the first symptom and then painful sores may develop a day or two later. Coxsackie A16 is currently the most common enterovirus that leads to the disease, though there are several other enteroviruses that can cause it as well.

Why the 1918 flu killed between 50 and 100 million people

The 1918–1920 flu pandemic (once called, incorrectly, the Spanish flu) killed quickly and in huge numbers, with estimates of the global death toll ranging from 50 to 100 million people. Several factors contributed to the high mortality rate: lack of antibiotics, the global disruption of World War I, and more.

How Alzheimer’s disease becomes fatal

Despite more than 100,000 people with Alzheimer's dying each year, the specific cause of death is not the disease itself. Often, secondary diseases arise from complications with the disease, including pneumonia, severe falls, malnutrition, or infection. Read more about the range of complications caused by Alzheimer’s here.

Breaking down the health effects of the El Niño-Southern Oscillation

Second only to the seasons, ENSO is the most significant source of variability in global climate, shifting rainfall and temperature patterns, particularly in Africa, Latin America, and South and Southeast Asia. The incidence of vector-borne diseases like malaria, respiratory diseases related to wildfire smoke, food insecurity, and drought-related health and nutritional impacts has been observed to be affected by ENSO.

Sepsis is the leading cause of death in hospitals

Sepsis is the result of an overly aggressive immune system trying to combat infection, triggering inflammation throughout the body. After it begins, each passing hour increases the risk of death by 4% to 9%, and an estimated 350,000 people die from the condition in the US each year.

Why bananas are in trouble

The average American eats over 25 pounds of bananas every year, but we won't for long if a deadly soil fungus continues to spread. Learn what scientists are doing to save the popular fruit.

Leprosy bacteria replicate extremely slowly—only once every two weeks

Mycobacterium leprae has a long incubation period and a very slow replication rate, taking roughly 12 to 14 days to make a copy of itself and divide. In contrast, bacteria like E. coli can replicate in about 20 minutes in ideal conditions. Someone can be infected for years without experiencing any symptoms. This also makes the disease difficult to treat. This video describes the knowns—and unknowns—about this infectious bacterium.

The deadliest aspect of volcanic eruptions is often not lava, but pyroclastic flows—avalanches of ash, gas, and rock that can move more than half the speed of sound.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

About 12.5% of US adults experience a phobia in their lifetime, a diagnosis that hinges on the intense fear interfering with daily life and persisting for at least six months.

Elk Cloner, the first computer virus to spread in public, was written as a practical joke by Richard Skrenta, a Pittsburgh high school student.

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

Poison ivy's rash-causing compound is found in the plant's roots, stem, and leaves—so coming into contact with any part of the plant can lead to rashes for the 85% of people who are allergic to it.

Louisiana's 'Cancer Alley' is infamous for having some of the highest industrial pollution, toxic air emissions, and cancer risks in the US.

US intelligence allegedly pursued more than 600 schemes to assassinate Cuban revolutionary Fidel Castro.

The US dollar is the most widely circulated currency in the world, and is involved in nearly 90% of global transactions