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

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.

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.

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

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.

See the evolution of Ebola vaccine and treatment development.

See the evolution of Ebola vaccine and treatment development

The recently approved vaccine and treatments against Ebola are the result of many years of investments and have reshaped how the world addresses Ebola outbreaks. Four drugs were tested in the midst of the 2014 outbreak. Two proved to be so effective the clinical trial ended early. The vaccine proved effective during the 2018-2020 outbreak in the DRC.

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

Awareness of local burial and grieving traditions eventually helped healthcare workers fight the spread of the virus. As healthcare workers and burial teams altered their procedures during the 2014 West African Ebola outbreak, and as community leaders pressed people to adapt traditional ceremonies, the spread of Ebola began to slow.

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.

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.

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.

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.)

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

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.

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

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.

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.

Explore what it's like inside a patient isolation unit, used in situations such as treating a patient or suspected patient with Ebola.

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, though it sometimes twists and can resemble a bowl of spaghetti.

Europe’s first recorded influenza pandemic swept the continent in 1580

The 1580 influenza pandemic, traced from Asia to Africa and into Europe, became the first flu outbreak clearly documented across the continent—killing tens of thousands and highlighting influenza’s potential for rapid global spread.

HIV originated in Central and West Africa from a virus in chimpanzees

Researchers believe the virus crossed from chimpanzees to humans through bushmeat practices in the early 20th century, with genetic studies suggesting the most recent common ancestor of the HIV-1 M group, which is responsible for the global AIDS pandemic, emerged around 1910–1930 in Léopoldville (now Kinshasa) in the Belgian Congo.

Since 1600, the longest stretch without an outbreak that killed 10,000 was four years

We think of pandemics as unlikely events, but disease outbreaks are surprisingly common. Over the past 400 years, the longest stretch without an outbreak that killed at least 10,000 people was just four years. The next pandemic can't be precisely known, so experts and policymakers focus on preparation.

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...

See what regions report new leprosy cases

This graphic shows the burden of leprosy by region for 2023, based on data provided from the World Health Organization, which collates this information. Southeast Asia leads in the number of cases by region. (Some readers may experience a paywall.)

More than 4,000 people died from cholera in 2023

This global health threat sickened more than half a million people in 2023 and killed 4,007 people. That's a 71% increase in deaths as compared to a year earlier. (Report only offered in PDF format.)

How drug trafficking undermines West Africa

The rise of drug trafficking is undermining institutions, public health, and development efforts in West Africa. According to the West African Commission on Drugs, civil wars have receded, democracy has gained ground, and economies are growing in...

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.

An interactive documentary exploring violence in the Central African Republic

This photographic and audio documentary explores a decade of violence in the Central African Republic. In March 2013, rebel groups in the north of the country united to form Seleka, which went on to take power of CAR’s capital. Waves of violence...

How a scientist discovered West Nile is spread by birds

Listen to Tracey McNamara, former chief pathologist at the Bronx Zoo, detailing her surprising late 1990s discovery that established West Nile virus is spread by birds. Financing animal disease surveillance studies, she says, saves human lives and surveillance gaps may fuel missed opportunities to identify dangerous diseases before they jump between species.

Visualizing the genetics of SARS-CoV-2

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, began with an outbreak in Wuhan, China in December 2019, and rapidly spread worldwide in early 2020. On March 11, 2020, the World Health Organization declared COVID-19 a global pandemic, leading to widespread lockdowns, travel restrictions, and economic disruptions.

See how a 2018 fire in Paradise, California, exposed the limits of emergency coordination

This Frontline documentary shows how the Camp Fire stretched and ultimately overwhelmed the complex web of agencies involved in emergency response, including fire suppression, 911 dispatch, law enforcement, and emergency management, with catastrophic results.

Find out how prevalent the flu is at this current moment

Updated weekly, this USAFacts resource shares current data from the CDC detailing how many cases of influenza and other flu-like illnesses accounted for doctor's visits. Monitor the spread of respiratory illness during flu season with this handy resource and prepare accordingly.

Yellow fever sidelined more US troops than enemy fire during the Spanish-American War

The disease, transmitted by the Aedes aegypti mosquito, sickened more than 2,000 soldiers. Fewer than 400 American soldiers died in the 1898 war.

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.

European powers carved up nearly all of Africa in just 4 decades

This video explains the "Scramble for Africa," when seven European nations seized over 90% of the continent between 1870 and 1910. Only Liberia and Ethiopia remained sovereign as imperial competition redrew Africa’s borders and reshaped its future.

Explore this hantavirus cruise ship outbreak case map from May 2026

Assembled from case information from state and health agencies, this detailed mapping includes the last known locations of each confirmed, deceased, and suspected case and their status.

View the ten deadliest tornadoes in US history.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in casualties, forces mobilized, and displacement of civilians.

The US first hosted the World Cup in 1994, a tournament that lives in soccer infamy for its poor planning and the murder of Colombian player Andres Escobar, who'd accidentally scored on his own net.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

Fireworks-related ER visits are on the rise—in 2024, they increased by 52% as compared to the prior year.

The tragic Pulitzer Prize-winning image 'The Vulture and the Little Girl' (1993) generated controversy, raised concerns about ethics in photography, and eventually led to the photographer's death.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

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.

20,000 letters to the advice columnist 'Dear Abby' provide insight into prevailing sex, religion, and LGBTQ fears, anxieties, and concerns from the 1950s onward.

Watch contemporary footage covering the US-backed Shah of Iran fleeing the country in the face of the 1979 Iranian Revolution

Electrical grids worldwide must double their power delivery capacity by 2050 to meet surging demand from AI and electric vehicles.

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

Double world record holder Hunter Ewen helped conquer his fear of balloons, called globophobia, by training to win Guinness World Record titles for balloon inflation.