Marburg virus, related to Ebola, is also extremely deadly

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.

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.

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.

Ebola has an average fatality rate above 50%

The Ebola virus is one of the planet’s most feared bugs. Symptoms begin with fever and fatigue but quickly develop into severe vomiting, diarrhea, and internal and external bleeding. But why is it so deadly? In short, Ebola hijacks the immune system to rapidly make replicas of itself.

An Ebola vaccine was developed during the 2018 west African Ebola outbreak, but the 2026 Ebola outbreak is with a different species of the virus, not the one that the vaccine is approved to treat.

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

Ebola's natural reservoir species are likely bats

But the virus doesn't seem to sicken the animals, so capturing an infected bat and performing necessary tests has remained challenging. Though many scientists believe fruit bats are the reservoir species for the virus, Ebola viral RNA fragments were detected in a greater long-fingered bat captured in 2016 in Liberia. The species isn't a fruit bat—it roosts in caves and feeds on insects. The scientist behind the discovery states that he believes the virus likely infects multiple host species and that the hosts may differ regionally. (Some users may encounter a paywall.)

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.

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.

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.

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

Clinics in the Democratic Republic of Congo saw patients with Ebola symptoms months before the disease was identified. The identification lag was due to inadequate diagnostics that could not accurately or quickly identify the virus's myriad species. Contact tracing and better diagnostics will be required to tamp down the outbreak.

See the evolution of Ebola vaccine and treatment development.

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

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

More than 70% of all new infectious diseases originate in animals. Referred to as zoonotic diseases, these are diseases that originate in animals and occasionally spill over or jump from animals to humans. Bats, mosquitoes, and primates have all been linked to spillover events. As human populations push further into previously uninhabited wilderness, animal-human contact increases, and disease spillover is inevitable.

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

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...

Ebola species have historically been named after where they were discovered, stigmatizing residents who live there, including Bundibugyo, in Uganda.

Using mosquitoes to vaccinate bats could curb the spread of deadly diseases

Researchers in China tested a transmissible rabies vaccine in the lab by feeding mosquitoes blood containing the vaccine and observing what happened to bats when they were either bitten by the mosquitoes or fed on them. The bats developed antibodies against rabies and survived subsequent rabies infection. (Some users may encounter a paywall.)

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

Explore 3D models of some of the most dangerous viruses

Everyone has come in contact with common viruses—typically something like influenza (the common flu)—but sometimes they encounter more dangerous strains. While we're familiar with the symptoms that manifest, it wasn't until the advent of advanced microscopy that scientists could pin down the exact structure and behavior of various viruses.

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

Monoclonal Antibodies mimic the antibodies produced naturally by the immune system. These molecules target specific parts of the virus, preventing them from entering cells or interfering with their ability to cause harm or infection.

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.

Every virus is classified into 7 groups based on genetic differences

Viruses infecting humans have been named based on symptoms ("chickenpox") or the location or animal in which they were first discovered ("Bolivian Haemorrhagic Fever" and "Monkeypox"). For clarity among scientists and to reduce stigma, virologists classify the 15,000 known viruses (270 of which infect humans) by their basic genetic material.

Live virus vaccines predated polio—that's how we vaccinate against smallpox

Since 1796, smallpox vaccines have used a live poxvirus related to smallpox. Yellow fever vaccines have used a live weakened form of the virus responsible for yellow fever since 1937.

Watch an expert's take on the rare disease hantavirus—and why it's not of great concern to the general population

This rare zoonotic disease, transmitted to humans primarily through infected rodent droppings, urine, or saliva, is rarely spread between people. The disease was of particular concern in spring 2026, when an outbreak occurred on a 150-person cruise ship, prompting a flurry of action, including contact tracing for passengers in their home countries. The disease can be fatal. But early care—primarily oxygen support—can help patients survive.

Experimental hantavirus vaccines and therapies, still under development, have long been funded by the US military.

Molecular evidence suggests the deadliest malaria parasite may be 100,000 years old

Plasmodium falciparum, the form of the parasite that kills the most humans, may date back 100,000 years, according to mitochondrial DNA analysis published in Science in 2003. It suggests that the parasite took off in humans about 10,000 years ago.

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.

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...

The similarly named foot-and-mouth disease doesn't affect humans, unlike HFMD

Though the names are similar, foot-and-mouth disease—also known as hoof-and-mouth disease—exclusively affects animals, primarily those with hooves, such as cattle, sheep, pigs, goats, and even giraffes. It doesn't sicken humans, though both this disease and hand, foot, and mouth disease do come from the same family of viruses—Picornaviridae.

Measles is one of the most contagious preventable diseases

The virus’s ability to persist in the air for up to two hours means an infected person could enter a room, leave, and two hours later infect someone else entering the room. Its location in the body’s upper respiratory tract also makes it easy for viral particles to be sneezed or coughed into the air.

A timeline of major pandemics from 1899–2025

Modern pandemics have been defined by the race between globalization (which increases risk) and the development of new medicines. The Great Influenza epidemic claimed some 50 million lives, and the COVID-19 pandemic killed more than 7 million. In between, diseases like Ebola, cholera, AIDS, and more have devastated communities.

Volcanoes in the 1340s likely helped trigger the Black Death

The "bubonic plague" that wiped out roughly half of Europe and Asia originated from many factors. Recent research suggests volcanic eruptions contributed as well. The "aerosol" effects of matter released from eruptions likely prompted famine and accelerated the spread of infected fleas riding on grains avoiding spoilage.

In 2012, a virus that causes HFMD may have killed dozens of kids in Asia

More than 50 young children in Cambodia died in spring 2012 for unknown reasons, but laboratory testing of samples available from a limited number of those children came back positive for Enterovirus 71. That virus, which can cause HFMD, is known to cause severe complications among some people who contract the disease. But health officials concluded that poor baseline health and then incorrect treatment using steroids helped exacerbate their condition, helping lead to the deaths.

This real-time tracking of the hantavirus cruise ship outbreak in May 2026 offers a unique glimpse into the global reach of the outbreak and whether the virus sickened passengers and their communities around the world.

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

The virus was officially described for the first time in 1789

Michael Underwood, an English physician and surgeon, was the first to describe the disorder, noting it caused disability in the lower extremities in children. Large-scale outbreaks of the disease were not observed until the late 19th century.

Epstein-Barr virus—the cause of 'kissing disease' mononucleosis—may be the leading cause of MS

A Harvard study with data from more than 10 million US military personnel found that people that contracted Epstein-Barr virus had a roughly 32-fold increased risk of developing multiple sclerosis. The work, published in 2022, found that Infection of the virus preceded MS onset by a median of five years, raising questions about better Epstein-Barr virus management and potential disease prevention.

There's no cure for West Nile virus—and infection can leave patients with permanent symptoms

This news story features Marie Heilman, a woman who became ill at age 40 from an infected mosquito bite in her yard. She says she was in a coma for 15 days, and though she woke up, she suffers from seizures, fatigue, vision issues, and has had two strokes.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

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

View the ten deadliest tornadoes in US history.

In 2019, a laptop loaded with six of the worst malware in history and described as 'an exhibit of historical weaponry' sold for $1.3M.

Poison ivy was sent to Europe in the 1600s as an exotic, ornamental oddity, where it was purposefully grown in the English royal gardens at Kew, the Faculty of Medicine in Paris, and a few other locations.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

Lesser-known phobias include turophobia, or the fear of cheese, and nomophobia, the fear of being without your cell phone.

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

Planarian flatworms are small, aquatic worms with exceptional regenerative capabilities. When cut, the worms can regenerate multiple bodies in a matter of weeks.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.