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Public Health

Vetted resources and information on current public health events.

What is Ebola Virus Disease?

Ebola virus disease (EVD) is a deadly disease with occasional outbreaks that occur mostly on the African continent. EVD most commonly affects people and nonhuman primates (such as monkeys, gorillas, and chimpanzees). It is caused by an infection with a group of viruses within the genus Ebolavirus:

  • Ebola virus (species Zaire ebolavirus)
  • Sudan virus (species Sudan ebolavirus)
  • Taï Forest virus (species Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus)
  • Bundibugyo virus (species Bundibugyo ebolavirus)
  • Reston virus (species Reston ebolavirus)
  • Bombali virus (species Bombali ebolavirus)

Of these, only four (Ebola, Sudan, Taï Forest, and Bundibugyo viruses) have caused disease in people.

Discovery of Ebolavirus

Ebola virus was first discovered in 1976 near the Ebola River in what is now the Democratic Republic of Congo. Since then, the virus has been infecting people from time to time, leading to outbreaks in several African countries. Scientists do not know where Ebola virus comes from. Based on similar viruses, they believe EVD is animal-borne, with bats or nonhuman primates being the most likely source. Infected animals carrying the virus can transmit it to other animals, like apes, monkeys, duikers and humans.

Future Directions

New research also suggests that outbreaks sparked by survivors of previous Ebola infection are becoming more common. The virus can persist in survivors for months and even years after recovery from acute illness. Unprotected sex with an Ebola survivor could pose a risk of infection, however causal contact does not. Thus, latent Ebolavirus in survivors could spark new EVD outbreaks in the future.

Zaire Ebolavirus (EBVOV)

Zaire Ebolavirus is the most common species of ebolavirus, and is often referred to simply as Ebola Virus (EBOV). It was fist discovered in what was formerly Zaire, now the  Democratic Republic of the Congo (DRC), in 1976. At first it was suspected to be a new strain of Marburg Virus, but was renamed "Ebola Virus" in 2010. It is responsible for the largest number of outbreaks, including the 2013-2016 Western Africa Ebola Virus Epidemic.

It is the most virulent strain of ebolavirus, accounting for approximately 1,400 human cases in 13 outbreaks over 35 years, with a case fatality rate <90%. The natural reservoir is believed to be fruit bats, and it can also be transmitted human-to-human and from other animals to humans through bodily fluids

Sudan Ebolavirus (SUDV)

The Sudan Ebolavirus was discovered in Sudan in 1977. It was introduced as Sudan Ebola Virus in 1998. Today, it is commonly referred to as "Sudan Virus" (SUDV).  It is clinically indistinguishable from the Zaire strain of Ebolavirus, however it is much less transmissible. The first outbreak of Sudan Virus was in South Sudan 1976, infecting 284 people and killing 151. There had been three other previous outbreaks of SUDV prior to the current outbreak in Uganda in September 2022.

The Sudan Virus is notable in that unlike the more common [Zaire] Ebola Virus, there is no vaccine available to prevent disease.

Bundibugyo ebolavirus (BDBV)

BDBV first appeared in 2007 in a viral hemorrhagic fever outbreak in the Bundibugyo District in Western Uganda. In this outbreak there were 149 confirmed human cases and 37 deaths (a case fatality rate of 35%). Bundibugyo virusvirus was first designated in 2008.

In August 2012 a second outbreak of Bundibugyo virus was reported by the the World Health Organization. It initially infected 15 and killed 10 (including 3 HCW) in the Orientale Province in the Democratic Republic of the Congo (DRC). By November 2012 the DRC announced that the final outbreak count was 77 human cases (36 confirmed, 17 probable, and 24 suspected) with 36 deaths (case fatality rate of 47%).

Taï Forest ebolavirus (TAFV)

Formally known as Côte d’Ivoire ebolavirus (CIEBOV), it was first introduced as new strain of Ebolavirus in 1995. There has only been a single known human infection of TAFV, a scientist performing necropsies on infected Western Chimpanzees during a viral hemorrhagic fever outbreak in 1994. Her disease course was similar to Dengue Fever and she had a full recovery within six weeks of infection.

Symptoms may appear anywhere from 2 to 21 days after contact with the virus, with an average of 8 to 10 days. The course of the illness typically progresses from “dry” symptoms initially (such as fever, aches and pains, and fatigue), and then progresses to “wet” symptoms (such as diarrhea and vomiting) as the person becomes sicker.

Primary signs and symptoms of Ebola often include some or several of the following:

  • Fever
  • Aches and pains, such as severe headache and muscle and joint pain
  • Weakness and fatigue
  • Sore throat
  • Loss of appetite
  • Gastrointestinal symptoms including abdominal pain, diarrhea, and vomiting
  • Unexplained hemorrhaging, bleeding or bruising

Other symptoms may include red eyes, skin rash, and hiccups (late-stage).

Ebola is a zoonotic virus and cientists think people are initially infected with Ebola virus through contact with an infected animal, such as a fruit bat or nonhuman primate. From there it can quickly spread from person-to-person.

The virus spreads through direct contact (such as through broken skin or mucous membranes in the eyes, nose, or mouth) with:

  • Blood or body fluids (urine, saliva, sweat, feces, vomit, breast milk, amniotic fluid, and semen) of a person who is sick with or has died from Ebola virus disease (EVD).
  • Objects (such as clothes, bedding, needles, and medical equipment) contaminated with body fluids from a person who is sick with or has died from EVD.
  • Infected fruit bats or nonhuman primates (such as apes and monkeys).
  • Semen from a man who recovered from EVD (through oral, vaginal, or anal sex). The virus can remain in certain body fluids (including semen) of a patient who has recovered from EVD, even if they no longer have symptoms of severe illness. There is no evidence that Ebola can be spread through sex or other contact with vaginal fluids from a woman who has had Ebola.
Country Cases Deaths Species Year
Uganda 164 77 Sudan ebolavirus 2022
Dem. Rep of the Congo 6 6 Zaire ebolavirus 2022
Guinea 23 12 Zaire ebolavirus 2021
Dem. Rep of the Congo 12 6 Zaire ebolavirus 2021
Dem. Rep. of the Congo 130 55 Zaire ebolavirus 2020
Dem. Rep. of the Congo, Uganda 3,470 2,287 Zaire ebolavirus 2018-2020
Dem. Rep. of the Congo 54 33 Zaire ebolavirus 2018
Dem. Rep. of the Congo 8 4 Zaire ebolavirus 2017
Dem. Rep. of the Congo 66 49 Zaire ebolavirus 2014
West African Ebola Epidemic (Multiple Countries) 28,646 11,323 Zaire ebolavirus 2014-2016
Uganda 6* 3* Sudan ebolavirus 2012
Dem. Rep. of the Congo 36* 13* Bundibugyo ebolavirus 2012
Uganda 11* 4* Sudan ebolavirus 2012
Uganda 1 1 Sudan ebolavirus 2011
Dem. Rep. of the Congo 32 15 Zaire ebolavirus 2008
Uganda 149 37 Bundibugyo ebolavirus 2007
Dem. Rep. of the Congo 264 187 Zaire ebolavirus 2007
Sudan (present day South Sudan) 17 7 Sudan ebolavirus 2004
Republic of Congo 35 29 Zaire ebolavirus 2003
Republic of Congo 143 128 Zaire ebolavirus 2002
Republic of Congo 57 43 Zaire ebolavirus 2001
Gabon 65 53 Zaire ebolavirus 2001
Uganda 425 224 Sudan ebolavirus 2000
South Africa 2 1 Zaire ebolavirus 1996
Gabon 60 45 Zaire ebolavirus 1996
Gabon 37 21 Zaire ebolavirus 1996
Zaire (present day DRC) 315 250 Zaire ebolavirus 1995
Côte d’Ivoire (Ivory Coast) 1 0 Taï Forest ebolavirus 1994
Gabon 52 31 Zaire ebolavirus 1994
Sudan (present day South Sudan) 34 22 Sudan ebolavirus 1979
Zaire (present day DRC) 1 1 Zaire ebolavirus 1977
Sudan (present day South Sudan) 284 151 Sudan ebolavirus 1976
Zaire (present day DRC) 318 280 Zaire ebolavirus 1976

What is Marburg Virus Disease (MVD)?

Marburg virus disease (MVD) is a rare but severe hemorrhagic fever which affects both people and non-human primates. MVD is caused by the Marburg virus, a genetically unique zoonotic (or animal-borne) RNA virus of the filovirus family. The six species of Ebola virus are the only other known members of the filovirus family.

Marburg virus was first recognized in 1967, when outbreaks of hemorrhagic fever occurred simultaneously in laboratories in Marburg and Frankfurt, Germany and in Belgrade, Yugoslavia (now Serbia). Thirty-one people became ill, initially laboratory workers followed by several medical personnel and family members who had cared for them. Seven deaths were reported. The first people infected had been exposed to Ugandan imported African green monkeys or their tissues while conducting research.

Marburg Virus Host

The reservoir host of Marburg virus is the African fruit bat, Rousettus aegyptiacus. This African fruit bat is a sighted, cave-dwelling bat that is found widely across Africa. Given the fruit bat’s broad geographic spread, more areas are potentially at risk for outbreaks of MVD than previously suspected. The virus is not known to be native to other continents, such as North America.

Fruit bats infected with Marburg virus do not show obvious signs of illness. Primates (including people) can become infected with Marburg virus, which can cause serious illness or death. Further study is needed to determine if other species may also host the virus.

Spillover to Humans

It is unknown how Marburg virus first spreads from its animal host to people; however, for the 2 cases in tourists visiting Uganda in 2008, unprotected contact with infected bat feces or aerosols are the most likely routes of infection.

Human-to-Human Transmission

After this initial crossover of virus from host animal to people, transmission occurs through person-to-person contact. The virus spreads through contact (such as through broken skin or mucous membranes in the eyes, nose, or mouth) with:

  • Blood or body fluids (urine, saliva, sweat, feces, vomit, breast milk, amniotic fluid, and semen) of a person who is sick with or died from Marburg virus disease
  • Objects contaminated with body fluids from a person who is sick with or has died from Marburg virus disease (such as clothes, bedding, needles, and medical equipment)
  • Semen from a man who recovered from MVD (through oral, vaginal, or anal sex)*

*Data on Marburg virus is limited; however, it is known to persist in the testicles and inside of the eye, similar to ebolaviruses. Since Marburg virus and ebolaviruses are both in the same virus family (Filoviridae) it can be assumed that persistence of the Marburg virus in other immune privileged sites (placenta, central nervous system) may be similar. There is no evidence that Marburg virus can spread through sex or other contact with vaginal fluids from a woman who has had MVD.

Incubation & Early Symptoms

After an incubation period of 2-21 days, symptom onset is sudden and marked by fever, chills, headache, and myalgia.

Progression of Infection

Around the fifth day after the onset of symptoms, a maculopapular rash, most prominent on the trunk (chest, back, stomach), may occur. Nausea, vomiting, chest pain, a sore throat, abdominal pain, and diarrhea may appear. Symptoms become increasingly severe and can include jaundice, inflammation of the pancreas, severe weight loss, delirium, shock, liver failure, massive hemorrhaging, and multi-organ dysfunction.


Clinical diagnosis of Marburg virus disease (MVD) can be difficult. Many of the signs and symptoms of MVD are similar to other infectious diseases (such as malaria or typhoid fever) or viral hemorrhagic fevers that may be endemic in the area (such as Lassa fever or Ebola). This is especially true if only a single case is involved.

Case Fatality Rate (CFR)

The case-fatality rate for MVD is between 23-90%. For a complete listing of the case fatality rates for each outbreak, please see the History of Outbreaks table.


There is no specific treatment for Marburg virus disease. Supportive hospital therapy should be utilized, which includes balancing the patient’s fluids and electrolytes, maintaining oxygen status and blood pressure, replacing lost blood and clotting factors, and treatment for any complicating infections.

Known Cases and Outbreaks of Marburg virus disease, in Chronological Order
Year(s) Location Suspected Origin of Infection Reported Human Cases Reported Deaths Among Cases (%) Situation
1967 Germany and Yugoslavia Uganda 31 7 (23%) Simultaneous outbreaks occurred in laboratory workers handling African green monkeys imported from Uganda. In addition to the 31 reported cases, an additional primary case was retrospectively serologically diagnosed.
1975 Johannesburg, South Africa Zimbabwe 3 1 (33%) A man with a recent travel history to Zimbabwe was admitted to hospital in South Africa. Infection spread from the man to his traveling companion and a nurse at the hospital. The man died, but both women were given vigorous supportive treatment and eventually recovered.
1980 Kenya Kenya 2 1 (50%) Recent travel history included a visit to Kitum Cave in Kenya’s Mount Elgon National Park. Despite specialized care in Nairobi, the male patient died. A doctor who attempted resuscitation developed symptoms 9 days later but recovered.
1987 Kenya Kenya 1 1 (100%) A 15-year-old Danish boy was hospitalized with a 3-day history of headache, malaise, fever, and vomiting. Nine days prior to symptom onset, he had visited Kitum Cave in Mount Elgon National Park. Despite aggressive supportive therapy, the patient died on the 11th day of illness. No further cases were detected.
1990 Russia Russia 1 1 (100%) Laboratory contamination
1998-2000 Democratic Republic of Congo (DRC) Durba, DRC 154 128 (83%) Most cases occurred in young male workers at a gold mine in Durba, in the north-eastern part of the country, which proved to be the epicentre of the outbreak. Cases were subsequently detected in the neighboring village of Watsa.
2004-2005 Angola Uige Province, Angola 252 227 (90%) Outbreak believed to have begun in Uige Province in October 2004. Most cases detected in other provinces have been linked directly to the outbreak in Uige.
2007 Uganda Lead and gold mine in Kamwenge District, Uganda 4 1 (25%) Small outbreak, with 4 cases in young males working in a mine. To date, there have been no additional cases identified.
2008 USA Cave in Maramagambo forest in Uganda, at the southern edge of Queen Elizabeth National Park, Uganda 1 0 (0%) A U.S traveler returned from Uganda in January 2008. The patient developed illness 4 days after returning, was hospitalized, discharged and fully recovered. The patient was retrospectively diagnosed with Marburg virus infection
2008 Netherlands Cave in Maramagambo forest in Uganda, at the southern edge of Queen Elizabeth National Park, Uganda 1 1 (100%) A 40-year-old Dutch woman with a recent history of travel to Uganda was admitted to hospital in the Netherlands. Three days prior to hospitalization, the first symptoms (fever, chills) occurred, followed by rapid clinical deterioration. The woman died on the 10th day of the illness.
2012 Uganda Kabale 15 4 (27%) Testing at CDC/UVRI identified a Marburg virus disease outbreak in the districts of Kabale, Ibanda, Mbarara, and Kampala over a 3 week time period.
2014 Uganda Kampala 1* 1 Overall, one case was confirmed (fatal) and 197 contacts were followed for 3 weeks. Out of these 197 contacts, 8 developed symptoms similar to Marburg, but all tested negative at the Uganda Virus Research Institute with support from CDC.
2017 Uganda Kween 4 3 (75%) A blood sample from Kween District in Eastern Uganda tested positive for Marburg virus. Within 24 hours of confirmation, a rapid outbreak response was begun. This outbreak occurred as a family cluster with no additional transmission outside of the four related cases.
2021 Guinea Guéckédou 1 1 (100%) One case was reported and confirmed by the Guinean Ministry of Health in a patient who was diagnosed after death. No additional cases were confirmed after more than 170 high-risk contacts were monitored for 21 days.
2022 Ghana Ashanti Region 3 2 A fatal suspect case of Marburg virus disease (MVD) was identified in the Ashanti region of Ghana on July 7, 2022. MVD was initially detected at Ghana’s national laboratory by polymerase chain reaction (PCR) and confirmed at the Institut Pasteur in Dakar, Senegal, marking the first detection of MVD in Ghana. Shortly after, two additional family members were also confirmed to have MVD. No additional cases outside the family cluster were identified. The outbreak was declared over in September.