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Ebola Virus Risk: A Global Look At The Effects

Your risk for ebola is extremely low, even if you travel to sub-Saharan Africa

Rapeepong Puttakumwong / Getty Images

Medically reviewed by Anju Goel, MD, MPH

Ebola is a viral illness that causes internal bleeding and kills about half of people who contract it. Ebola can be caused by four different types of viruses, and is most common in sub-Saharan Africa. Still, if you're traveling to an area that has had outbreaks in the past, it's important to know about ebola symptoms and how ebola spreads.

Continue reading to learn more about ebola, including its effects, ways to prevent it, and how it spreads.

Rapeepong Puttakumwong / Getty Images

Where Do Ebola Virus Outbreaks Occur?

Ebola most often happens in sub-Saharan Africa. The Democratic Republic of the Congo, formerly known as Zaire, has had the most outbreaks. An outbreak occurred in 2022 in Uganda and the Democratic Republic of the Congo.

Here's an overview of Ebola outbreaks over the past five years, including the number of infections and the death rate for each outbreak.

Uganda, 2022: 164 infections, 34% fatality rate

Democratic Republic of the Congo, 2022: Six infections, 100% fatality rate

Democratic Republic of the Congo, 2021: 23 cases, 65% fatality rate

Guinea, 2021: 23 confirmed cases, 52% fatality rate

Democratic Republic of the Congo, 2020: 130 cases, 42% fatality rate

Democratic Republic of the Congo, 2018: More than 3,500 cases, 66% fatality rate.

Symptoms: What Does Ebola Do to People?

Ebola is so deadly because it causes internal bleeding (hemorrhaging). That's why Ebola is known as a hemorrhagic fever. Symptoms of Ebola prior to hemorrhage include:

Fever

Headache

Muscle aches or joint pain

Sore throat

Diarrhea and other gastrointestinal issues

Loss of appetite

Unexplained bleeding or bruising

Rash

Red eyes

Hiccups

These symptoms can be caused by many other viral illnesses that are much less serious than Ebola, like the flu. So, it's important to consider the likelihood you were exposed to Ebola, such as by traveling to countries with Ebola outbreaks.

How Does Ebola Spread?

Ebola can spread from animals to people, and from person to person. Symptoms most often appear eight to 10 days after a person is exposed, although they sometimes won't appear for up to 21 days.

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Ebola is most often spread when you come into contact with infected bodily fluids, including:

Blood

Urine

Saliva

Sweat

Feces

Vomit

Breast milk

Amniotic fluid

Semen

You can also contract the disease from objects that have come into contact with infected bodily fluids. That might include medical instruments, sheets, or clothes from a person with Ebola.

You can also catch the virus from bats and primates, including monkeys and apes. If you eat meat from an Ebola-infected animal, you could contract the disease.

Sexual Transmission of Ebola

Ebola can continue to spread through semen even after a person has recovered from the disease. Anyone who has contact with someone's semen who has had ebola is at risk for the disease. Scientists don't think ebola can spread through vaginal fluids from a person who has recovered from the disease.

Limiting Ebola Risk While Traveling Abroad

Before you travel, check the Centers for Disease Control and Prevention (CDC) website for information on recent outbreaks of ebola. Keep in mind that it's rare for tourists to be exposed to Ebola. However, some people, like medical professionals, are at higher risk.

Still, the CDC recommends these precautions for Americans traveling to an area that has had an Ebola outbreak:

Avoid close contact with sick people.

Don't exchange bodily fluids with anyone, including through kissing.

Avoiding touching live or dead animals.

Don't eat or handle meat from wild animals.

Wear protective equipment when working with wild animals.

Wash your hands frequently. When that's not an option, use hand sanitizer.

Avoid touching your eyes, nose, and mouth with unclean hands.

Don't touch dead bodies, or objects that have been near dead bodies.

If you're traveling in sub-Saharan Africa and experience any signs of Ebola illness, seek medical help immediately, even if your symptoms seem mild at first.

Ebola Virus Vaccine: A Cure?

The Food and Drug Administration (FDA) approved an Ebola vaccine in 2019. The vaccine protects people against one virus that causes Ebola. This virus has caused the largest Ebola outbreaks, but it's not the cause of the 2022 outbreak in Uganda. That means the Ebola vaccine offers significant protection, but it's not a cure.

The CDC recommends that the following American adults get the Ebola vaccine:

Anyone working with the vaccine in a laboratory

Healthcare workers and first responders who work in an Ebola treatment center

Responding or planning to respond to an outbreak caused by Ebola virus

The CDC does not recommend routine vaccination for people traveling to Africa or elsewhere. If it's possible that you were exposed to Ebola and you are experiencing symptoms, call your healthcare provider immediately. They'll tell you what to do next and likely test you for ebola using blood tests or oral swabs.

Ebola is difficult to treat, but two treatments are approved for certain virus strains. Healthcare providers can also offer supportive care like oxygen, increased intravenous (IV) fluids, and dialysis (treatment to remove extra fluid and waste from blood when your kidneys fail to).

Summary

Ebola is an extremely rare virus in the United States. The only outbreaks have been in sub-Saharan Africa. Even there, tourists are at little risk. Still, you can reduce your risk for Ebola by avoiding contact with sick people, not exchanging bodily fluids, and not touching or eating wild animals. There is a vaccine for certain types of Ebola, but it's not recommended for most travelers since the risk of the illness is so low.

Ebola Fast Facts

CNN Editorial Research

(CNN) — Here's a look at Ebola, a virus with a high fatality rate that was first identified in Africa in 1976.

Facts

Ebola hemorrhagic fever is a disease caused by one of five different Ebola viruses. Four of the strains can cause severe illness in humans and animals. The fifth, Reston virus, has caused illness in some animals, but not in humans.

The first human outbreaks occurred in 1976, one in northern Zaire (now Democratic Republic of the Congo) in central Africa: and the other, in southern Sudan (now South Sudan). The virus is named after the Ebola River, where the virus was first recognized in 1976, according to the Centers for Disease Control and Prevention (CDC).

Ebola is extremely infectious but not extremely contagious. It is infectious, because an infinitesimally small amount can cause illness. Laboratory experiments on nonhuman primates suggest that even a single virus may be enough to trigger a fatal infection.

Ebola is considered moderately contagious because the virus is not transmitted through the air.

Humans can be infected by other humans if they come in contact with body fluids from an infected person or contaminated objects from infected persons. Humans can also be exposed to the virus, for example, by butchering infected animals.

Symptoms of Ebola typically include: weakness, fever, aches, diarrhea, vomiting and stomach pain. Additional experiences include rash, red eyes, chest pain, throat soreness, difficulty breathing or swallowing and bleeding (including internal).

Typically, symptoms appear eight to 10 days after exposure to the virus, but the incubation period can span two to 21 days.

Ebola is not transmissible if someone is asymptomatic and usually not after someone has recovered from it. However, the virus has been found in the semen of men who have recovered from Ebola and possibly could be transmitted from contact with that semen.

There are five subspecies of the Ebola virus: Zaire ebolavirus (EBOV), Bundibugyo ebolavirus (BDBV), Sudan ebolavirus (SUDV), Taï Forest ebolavirus (TAFV) and Reston ebolavirus (RESTV).

Click here for the CDC's list of known cases and outbreaks.

2014-2016 West Africa Outbreak

(Full historical timeline at bottom)

March 2014 – The CDC issues its initial announcement on an outbreak in Guinea, and reports of cases in Liberia and Sierra Leone.

April 16, 2014 – The New England Journal of Medicine publishes a report, speculating that the current outbreak's Patient Zero was a 2-year-old from Guinea. The child died on December 6, 2013, followed by his mother, sister and grandmother over the next month.

August 8, 2014 – Experts at the World Health Organization (WHO) declare the Ebola epidemic ravaging West Africa an international health emergency that requires a coordinated global approach, describing it as the worst outbreak in the four-decade history of tracking the disease.

August 19, 2014 – Liberia's President Ellen Johnson Sirleaf declares a nationwide curfew beginning August 20 and orders two communities to be completely quarantined, with no movement into or out of the areas.

September 16, 2014 – US President Barack Obama calls the efforts to combat the Ebola outbreak centered in West Africa "the largest international response in the history of the CDC." Speaking from the CDC headquarters in Atlanta, Obama adds that "faced with this outbreak, the world is looking to" the United States to lead international efforts to combat the virus.

October 6, 2014 – A nurse's assistant in Spain becomes the first person known to have contracted Ebola outside Africa in the current outbreak. The woman helped treat two Spanish missionaries, both of whom had contracted Ebola in West Africa, one in Liberia and the other in Sierra Leone. Both died after returning to Spain. On October 19, Spain's Special Ebola Committee says that nurse's aide Teresa Romero Ramos is considered free of the Ebola virus.

October 8, 2014 – Thomas Eric Duncan, a Liberian citizen who was visiting the United States, dies of Ebola in Dallas.

October 11, 2014 – Nina Pham, a Dallas nurse who cared for Duncan, tests positive for Ebola during a preliminary blood test. She is the first person to contract Ebola on American soil.

October 15, 2014 – Amber Vinson, a second Dallas nurse who cared for Duncan, is diagnosed with Ebola. Authorities say Vinson flew on a commercial jet from Cleveland to Dallas days before testing positive for Ebola.

October 20, 2014 – Under fire in the wake of Ebola cases involving two Dallas nurses, the CDC issues updated Ebola guidelines that stress the importance of more training and supervision, and recommend that no skin be exposed when workers are wearing personal protective equipment, or PPE.

October 23, 2014 – Craig Spencer, a 33-year-old doctor who recently returned from Guinea, tests positive for Ebola – the first case of the deadly virus in New York and the fourth diagnosed in the United States.

October 24, 2014 – In response to the New York Ebola case, the governors of New York and New Jersey announce that their states are stepping up airport screening beyond federal requirements for travelers from West Africa. The new protocol mandates a quarantine for any individual, including medical personnel, who has had direct contact with individuals infected with Ebola while in Liberia, Sierra Leone or Guinea. The policy allows the states to determine hospitalization or quarantine for up to 21 days for other travelers from affected countries.

January 18, 2015 – Mali is declared Ebola free after no new cases in 42 days.

February 22, 2015 – Liberia reopens its land border crossings shut down during the Ebola outbreak, and President Sirleaf also lifts a nationwide curfew imposed in August to help combat the virus.

May 9, 2015 – The WHO declares an end to the Ebola outbreak in Liberia. More than 4,000 people died.

November 2015 – Liberia's health ministry says three new, confirmed cases of Ebola have emerged in the country.

December 29, 2015 – WHO declares Guinea is free of Ebola after 42 days pass since the last person confirmed to have the virus was tested negative for a second time.

January 14, 2016 – A statement is released by the UN stating that "For the first time since this devastating outbreak began, all known chains of transmission of Ebola in West Africa have been stopped and no new cases have been reported since the end of November."

March 29, 2016 – The WHO director-general lifts the Public Health Emergency of International Concern related to the 2014-2016 Ebola outbreak in West Africa.

Timeline

*Includes information about Ebola and other outbreaks resulting in more than 100 deaths or special cases.

1976 – First recognition of the EBOV disease is in Zaire (now Democratic Republic of the Congo). The outbreak has 318 reported human cases, leading to 280 deaths. An SUDV outbreak also occurs in Sudan (now South Sudan), which incurs 284 cases and 151 deaths.

1995 – An outbreak in the Democratic Republic of the Congo (DRC) leads to 315 reported cases and at least 250 deaths.

2000-2001 – A Ugandan outbreak (SUDV) results in 425 human cases and 224 deaths.

December 2002-April 2003 – An EBOV outbreak in ROC results in 143 reported cases and 128 deaths.

2007 – An EBOV outbreak occurs in the DRC, 187 of the 264 cases reported result in death. In late 2007, an outbreak in Uganda leads to 37 deaths, with 149 cases reported in total.

September 30, 2014 – Dr. Thomas Frieden, director of the CDC, announces the first diagnosed case of Ebola in the United States. The person has been hospitalized and isolated at Texas Health Presbyterian Hospital in Dallas since September 28.

July 31, 2015 – The CDC announces that a newly developed Ebola vaccine is "highly effective" and could help prevent its spread in the current and future outbreaks.

December 22, 2016 – The British medical journal The Lancet publishes a story about a new Ebola vaccine that tested 100% effective during trials of the drug. The study was conducted in Guinea with more than 11,000 people.

August 1, 2018 – The DRC's Ministry of Health declares an Ebola virus outbreak in five health zones in North Kivu province and one health zone in Ituri province. On July 17, 2019, the WHO announces that the outbreak constitutes a public health emergency of international concern. On June 25, 2020, the DRC announces that the outbreak is officially over. A total of 3,481 cases were reported, including 2,299 deaths and 1,162 survivors.

August 12, 2019 – Two new Ebola treatments are proving so effective they are being offered to all patients in the DRC. Initial results found that 499 patients who received the two effective drugs had a higher chance of survival – the mortality rate for REGN-EB3 and mAb114 was 29% and 34% respectively. The two drugs worked even better for patients who were treated early – the mortality rate dropped to 6% for REGN-EB3 and 11% for mAb114, according to Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and one of the researchers leading the trial.

December 19, 2019 – The US Food and Drug administration announces the approval of a vaccine for the prevention of the Ebola virus for the first time in the United States. The vaccine, Ervebo, was developed by Merck and protects against Ebola virus disease caused by Zaire ebolavirus in people 18 and older.

October 14, 2020 – Inmazeb (REGN-EB3), a mixture of three monoclonal antibodies, becomes the first FDA-approved treatment for the Ebola virus. In December, the FDA approves a second treatment, Ebanga (mAb114).

January 14, 2023 – Ugandan authorities officially declare the end of a recent Ebola outbreak after 42 consecutive days with no new cases.

Ebola's Exponential Growth

Monday, October 13th 2014 - 00:26 UTC

The U.S. Government's Centers for Disease Control warned recently that we could have 1.4 million cases of Ebola by January.

By Gwynne Dyer - Here are two good things about the Ebola virus. It is unlikely to mutate into a version that can spread through the air, as some other viruses have done. And people who have been infected by Ebola cannot pass it on to others during the incubation period (between two and 21 days). Only when they develop detectable symptoms, notably fever, do they become infectious to others, and only by the transfer of bodily fluids.

Here are three bad things about Ebola.

The "bodily fluids" that can transmit it include even the tiniest droplet of sweat: just the slightest touch can pass the virus on. The death rate for those who become infected is 70%. And the U.S. Government's Centers for Disease Control warned recently that we could have 1.4 million cases of Ebola by January.

Since the number of known cases so far is only around 7,500, that suggests that the number of new cases is doubling approximately every two weeks. This is called exponential growth: not 1, 2, 3, 4, 5, 6... But 1, 2, 4, 8, 16, 32.... If you put one grain of wheat on the first square of a chess-board, two on the second, and keep doubling the grains every square, there are not enough grains of wheat in the world to get you to the 64th square.

Exponential growth always slows down eventually, but the question is when? A vaccine would slow it down, and the British pharmaceutical giant GlaxoSmithKline already has one under development, but it is still in an early stage of testing. Human volunteers are now being given the vaccine to check for unforeseen side effects.

If no serious side-effects are found, the vaccine will then be given to health workers in West Africa. A process that normally takes years is being compressed into mere months, and 10,000 doses of the vaccine are already being produced (for the health workers).

But it will be the end of the year before we know if it actually gives a useful degree of protection from the virus.

If it does, then millions of doses would have to be produced and injected into the people of Liberia, Sierra Leone, and Guinea, where Ebola is already an epidemic— or tens of millions of doses if the disease has spread by then to more populous countries like Ivory Coast, Ghana or, worst of all, Nigeria, which has 175 million people.

Until and unless a vaccine becomes available in very large quantities, the only way to stop the exponential spread of Ebola in the affected countries is to isolate the victims, a task that is very difficult in mostly rural countries with minimal medical facilities. Liberia with 4.2 million people, had only 51 doctors and 978 nurses and midwives at the start of the crisis, and some of those have already died or fled.

You don't need to find and isolate everybody who gets the disease to break the exponential pattern. Just isolating 75% of them as soon as they become infectious would drastically slow the spread. But at the moment, in the three most affected countries, only an estimated 18% of the victims are being taken to treatment centers (where, of course, most of them will die).

This is why the most important intervention so far has been the dispatch of 3,000 U.S. Troops to Liberia, with the primary job of creating 17 large tent hospitals and training 500 nurses to work in them. Britain is providing 200 new hospital beds in its former colony of Sierra Leone, with 500 more in the next few months. Cuba has sent 165 health workers, China has sent 60, and France has sent various teams to help its former colony, Guinea.

But with the exception of the American aid to Liberia, it is all woefully inadequate. Nine months after the first case of Ebola was confirmed in Guinea, we are still playing catch-up, and playing it badly. Why is that? Aren't the developed countries also at risk if the virus continues to spread?

Well, no, or at least their governments don't think so. Even without a vaccine, they are confident that their health services can find and isolate any infected people quickly and prevent Ebola from becoming an epidemic in their countries. They are probably right, and so they see the limited help they are sending to West Africa as charity rather than a vital self-interest. But they may be wrong.

As Professor Peter Piot, who first identified the Ebola virus in 1976, said in a recent interview with Der Spiegel, "I am more worried about the many people from India who work in trade or industry in West Africa. It would only take one of them to become infected, travel to India during the virus's incubation period to visit relatives, and then, once he becomes sick, go to a public hospital.

"Doctors and nurses in India often don't wear protective gloves. They would immediately become infected and spread the virus." Then you would have Ebola on the loose in a country of more than a billion people, millions of whom travel abroad each year. All hope of confining the disease to Africa and driving it back down to almost nothing, as was done in previous outbreaks, would be gone.

Ebola Virus Disease