Ebola is a severe and often fatal viral disease that causes fever, internal bleeding, and organ failure in humans and other primates. Average fatality rates have historically hovered around 50%, though individual outbreaks have ranged from 25% to as high as 90% depending on the virus species and available medical care. The virus belongs to the Filoviridae family, a group of thread-shaped viruses that also includes the Marburg virus.
The Six Known Species
Scientists recognize six species within the Ebolavirus genus: Zaire, Sudan, Tai Forest, Bundibugyo, Reston, and Bombali. Of these, Zaire ebolavirus is the deadliest and most common cause of outbreaks in humans. It was responsible for the massive 2014-2016 West Africa epidemic, the largest Ebola outbreak on record. Sudan ebolavirus carries the next highest fatality rate, followed by Bundibugyo. Reston ebolavirus is notable because it can infect humans but has never caused illness in people, only in nonhuman primates and pigs.
How the Virus Spreads
Fruit bats of the Pteropodidae family are considered the natural hosts of the virus. They carry it without becoming visibly ill, acting as a reservoir in tropical forest ecosystems. Humans typically pick up the virus through close contact with the blood, organs, or bodily fluids of infected animals, including chimpanzees, gorillas, monkeys, forest antelope, and porcupines found sick or dead in the rainforest.
Once in a human population, the virus spreads person to person through direct contact with the blood or body fluids of someone who is sick or has died from the disease. It can also spread through contaminated surfaces and objects. Burial ceremonies involving direct contact with the body of someone who died from Ebola have been a significant driver of transmission during outbreaks. Importantly, people cannot spread the virus before symptoms appear, and they remain infectious as long as the virus is present in their blood.
Ebola does not spread through air, water, or food the way influenza or COVID-19 does. It requires direct contact with infected fluids, which is why outbreaks tend to concentrate among family members, caregivers, and healthcare workers.
How the Virus Infects Cells
Ebola uses a spike protein on its surface to latch onto human cells and get pulled inside them. Once swallowed into a cell’s internal compartments, the virus relies on a specific human protein called NPC1, normally involved in cholesterol transport, to break free and begin replicating. Without functional NPC1, the virus gets trapped and cannot escape to spread through the body. This discovery has been an important target for understanding why some cells are more vulnerable than others.
Symptoms and Timeline
Symptoms appear 2 to 21 days after exposure, with most people getting sick 8 to 10 days in. The disease progresses in two recognizable phases.
The early phase, sometimes called the “dry” phase, looks a lot like the flu: fever, severe headache, muscle and joint pain, weakness, fatigue, and sore throat. There’s nothing distinctive enough at this stage to immediately identify Ebola over other tropical illnesses like malaria or typhoid.
After about four to five days of illness, the disease can escalate to its “wet” phase. This is when the hallmark gastrointestinal symptoms hit: nausea, vomiting, severe diarrhea, and abdominal pain. Unexplained bleeding, both internal and external, can occur, though not in every patient. Some people also experience chest pain, shortness of breath, confusion, red eyes, skin rash, hiccups, and seizures. The massive fluid loss from vomiting and diarrhea is often what pushes patients toward organ failure.
How Ebola Is Diagnosed
The gold standard for confirming Ebola is a reverse transcription polymerase chain reaction (RT-PCR) test, which detects the virus’s genetic material in a blood sample. Rapid diagnostic tests also exist and are used in field settings during outbreaks, but a positive diagnosis still requires RT-PCR confirmation. Because early symptoms overlap with many other diseases, lab testing is essential for identifying cases and triggering the right public health response.
Treatment Options
For decades, Ebola treatment was limited to supportive care: replacing lost fluids, maintaining blood pressure, and treating secondary infections. That changed with the development of monoclonal antibody therapies, lab-made proteins designed to bind to the virus and help the immune system neutralize it.
The FDA has approved a monoclonal antibody treatment for Zaire ebolavirus. In a major clinical trial (the PALM trial), 35.1% of patients who received the treatment died within 28 days, compared to 49.4% of patients in the control group. That’s a meaningful reduction, though the fatality rate remains high. Treatment works best when given early, which reinforces the importance of rapid diagnosis.
Vaccination
A single-dose vaccine called ERVEBO is available and targets Zaire ebolavirus. It begins providing protection 10 days after vaccination, with the body producing detectable antibodies within 7 to 10 days. The vaccine has been deployed during outbreaks using a “ring vaccination” strategy, where contacts of confirmed cases and contacts of those contacts receive the shot to create a buffer of immunity around each new case. This approach was credited with helping contain several outbreaks in the Democratic Republic of the Congo.
Life After Ebola: Post-Recovery Complications
Surviving Ebola doesn’t mean a clean return to health. Many survivors experience a collection of lingering problems known as Post-Ebola Syndrome. These can include chronic fatigue, joint pain, muscle aches, headaches, hair loss, and memory problems. Some survivors develop vision loss, including a form of eye inflammation that can lead to permanent blindness. Hearing loss, tinnitus, insomnia, depression, anxiety, and post-traumatic stress disorder are also common.
Perhaps most concerning from a public health perspective, the virus can persist in certain body sites long after it clears from the bloodstream. Viral genetic material has been detected in semen up to 40 months after illness onset, and in cerebrospinal fluid up to 10 months, in breast milk up to 16 months, and in the fluid of the eye up to 14 weeks. This persistence means survivors may pose a transmission risk through sexual contact for months or even years. Male survivors are typically advised to have their semen tested before resuming unprotected sexual activity.
Outbreak Prevention and Control
Containing an Ebola outbreak depends on a hierarchy of controls. Engineering and administrative measures come first: isolating patients, setting up dedicated treatment centers, training healthcare staff, and establishing safe burial practices. Personal protective equipment (PPE) is critical but considered the last layer of defense, not the first.
WHO guidelines specify different levels of PPE depending on the activity and how close workers need to get to patients. Screening and triage, where a distance of at least 1 meter can be maintained, require less protection than direct patient care or handling the deceased. The guidelines address practical details like when to use single versus double gloves, how to disinfect gloves, and when to change them between patients. Notably, the WHO now strongly recommends against the once-common practice of spraying healthcare workers or the deceased with chlorine-based disinfectants.
Safe and dignified burial protocols remain one of the most important and culturally sensitive aspects of outbreak response. Because traditional burial practices in many affected communities involve washing and touching the body, public health teams work with community leaders to develop alternatives that respect cultural values while preventing transmission.