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. One additional case was diagnosed retrospectively.

The reservoir host of Marburg virus is the African fruit bat, Rousettus aegyptiacus. Fruit bats infected with Marburg virus do not show obvious signs of illness. Primates (including people) can become infected with Marburg virus, and may develop serious disease with high mortality. Further study is needed to determine if other species may also host the virus.

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.

The reservoir host of Marburg virus is the African fruit bat, Rousettus aegyptiacus. 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.

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.

MVD appears in sporadic outbreaks throughout sub-Saharan Africa. Many past outbreaks started with male mine workers in bat-infested mines. The virus then spread within their communities through cultural practices, within families, and among healthcare staff. It is possible that isolated cases occur occasionally, as well, but go unrecognized.

Cases of MVD in people have occurred outside Africa but are infrequent. In addition to the 1967 laboratory exposures in Europe that led to the discovery of the virus, a Dutch tourist developed MVD after returning to the Netherlands from Uganda in 2008, and subsequently died. That same year, an American traveler developed MVD after returning to the US from Uganda and recovered. Both travelers had visited a well-known cave inhabited by fruit bats in a national park.

Viruses in the family Filoviridae can cause severe hemorrhagic fever in people and nonhuman primates (such as monkeys and gorillas) and may spread in other animals, such as bats. Filoviruses are enveloped in a lipid (fatty) membrane and appear in several shapes. Each virion (complete, infective form of a virus) contains one molecule of single-stranded, negative-sense RNA.

Discovery of Filoviruses

In 1967, Marburg virus, the first discovered filovirus, was recognized when laboratory workers in Marburg, Germany and Yugoslavia developed hemorrhagic fever after handling tissues from green monkeys. The virus disappeared until 1975, when it emerged in South Africa in a traveler to Zimbabwe, and quickly spread to the traveler’s companion and a nurse caring for him. Since then, Marburg has emerged sporadically, including two large epidemics in Democratic Republic of Congo (DRC) from 1998-2000 and Angola from 2004-2005.

Ebola virus disease was first identified in 1976 when two consecutive outbreaks of fatal hemorrhagic fever occurred in different parts of Central Africa. The first outbreak occurred in DRC in a village near the Ebola River, giving the virus its name. The second outbreak occurred in what is now South Sudan, approximately 500 miles (850 km) away. Since then, six different species of ebolavirus have been discovered, four of which are known to cause disease in people.

How viruses in the Filovirus family spread

Filoviruses are zoonotic, meaning they are transmitted from animals to people. The reservoir host of Marburg virus is the African fruit bat, but further study is needed to determine if other species may also serve as hosts. Scientists have not determined the host for Ebola virus, although bats are likely involved and may be the reservoir.

Factors like population growth, encroachment into forested areas, and direct interaction with wildlife (such as bushmeat consumption) may contribute to the introduction of filoviruses into human populations. Once a person is infected, filoviruses can spread from person-to-person through direct contact with an infected person’s body fluids. Those at highest risk of infection are caretakers and healthcare providers who do not use appropriate personal protective equipment (PPE).

People may be at risk of exposure to Marburg virus if they have close contact with:

• African fruit bats (Rousettus aegyptiacus – the reservoir host of Marburg virus), or their urine and/or excretions;
• People sick with Marburg virus disease; or
• Non-human primates infected with Marburg virus

Historically, the people at highest risk include family members and hospital staff who care for patients infected with Marburg virus and have not used proper infection prevention and control measures. Certain occupations, such as veterinarians and laboratory or quarantine facility workers who handle non-human primates from Africa, may also be at increased risk of exposure to Marburg virus.

Exposure risk can be higher for those travelers visiting endemic regions in Africa who have contact with fruit bats (Rousettus aegyptiacus), or enter caves or mines inhabited by these bats.

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.

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, or
• 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.

Spread of the virus between people has occurred in close environments and among direct contacts. A common example is through caregivers in the home or in a hospital (nosocomial transmission).

In previous outbreaks, people who have handled infected nonhuman primates or have come in direct contact with their body fluids have become infected with Marburg virus. Laboratory exposures can also occur when lab staff handle live Marburg virus.

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

The case-fatality rate for MVD is between 23-90%.

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, typhoid fever, or dengue) 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.

If a person has early symptoms of MVD and a possible exposure to Marburg virus, the patient should be isolated and public health professionals notified. Samples from the patient can then be collected and tested to confirm infection.

Antigen-capture enzyme-linked immunosorbent assay (ELISA) testing, polymerase chain reaction (PCR), and IgM-capture ELISA can be used to confirm a case of MVD within a few days of symptom onset. Virus isolation may also be performed but should only be done in a high containment laboratory with good laboratory practices. The IgG-capture ELISA is appropriate for testing persons later in the course of disease or after recovery. In deceased patients, immunohistochemistry, virus isolation, or PCR of blood or tissue specimens may be used to diagnose MVD retrospectively.

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.

Experimental treatments are validated in non-human primate models but have never been tried in humans.

Preventive measures against Marburg virus infection are not well defined, as transmission from wildlife to people remains an area of ongoing research. However, avoiding fruit bats (Rousettus aegyptiacus), and sick non-human primates is one way to protect against infection.

Measures for prevention of secondary, or person-to-person, transmission are like those used for other hemorrhagic fevers. If a patient is either suspected or confirmed to have Marburg virus disease (MVD), infection prevention and control measures should be used to prevent direct physical contact with the patient. These precautions include wearing protective gowns, gloves, and masks; placing the infected individual in strict isolation; and sterilization or proper disposal of needles, equipment, and patient excretions.

MVD is a very rare disease in people. However, when it occurs, it has the potential to spread to other people, especially healthcare staff and family members who care for the patient. Increasing awareness in communities and among healthcare providers of the clinical symptoms of patients with MVD is critical. Better awareness can lead to earlier and stronger precautions against the spread of Marburg virus in both family members and health-care providers.

Improving the use of diagnostic tools is another priority. With modern means of transportation giving access even to remote areas, it is possible to obtain rapid testing of samples in disease control centers equipped with Biosafety Level 4 laboratories (laboratories equipped with the highest level of biosafety precautions) to confirm or rule out Marburg virus infection.

What are Ebola and Marburg?

Ebola virus disease and Marburg virus disease are viral hemorrhagic fevers. These diseases damage organs and blood vessels and may cause death. A person can get infected with Ebola or Marburg viruses if they touch or handle the following:

• Body fluids from an infected person, such as blood, urine, saliva, sweat, feces, vomit, breast milk, semen, and others.
• Objects contaminated with the body fluids of an infected person, such as clothes, bedding, needles, and medical equipment.
• Infected wild animals, for example bats and primates, or their body fluids or meat (bushmeat).

Ebola and Marburg symptoms may start anywhere from 2 to 21 days after a person is infected (for Ebola, the average is 8-10 days) and may include sudden fever, chills, headache, body aches, and a rash on the chest, back, and stomach. As the person gets sicker, they can have nausea, vomiting, chest pain, sore throat, abdominal pain, and diarrhea.

People with Ebola or Marburg are at risk for internal bleeding, critically low blood pressure (shock), damage to multiple organs and organ systems (liver, pancreas, kidneys, brain), and death.

Who is at risk?

Most travelers have low chances of getting infected with Ebola or Marburg viruses.

Ebola and Marburg viruses are found in sub-Saharan Africa.

Travelers to sub-Saharan Africa who work closely with or visit areas with bats or non-human primates, such as monkeys, chimpanzees, and gorillas, may be more likely to get infected. For example, two tourists visiting Uganda in 2008 who were infected with Marburg virus were likely exposed while visiting a cave known for its large bat population. People who care for patients with Ebola or Marburg disease may also be more likely to get infected due to exposure to their blood or body fluids.

What can travelers do to prevent Ebola and Marburg?

You can protect yourself from infection by taking the following steps.

• Avoid close contact with sick people and blood or body fluids from all people
  • Do not kiss, hug, or share eating utensils or cups.
  • Don't touch items that may have blood or body fluids on them.
• Avoid animals when traveling
  • Don't touch live or dead animals.
  • Avoid markets or farms with animals.
  • Don't eat or handle meat from wild animals.
  • If you are traveling to work with animals, wear appropriate protective gear.
• Wash your hands
  • Wash hands often with soap and water. If soap and water aren’t available, use an alcohol-based hand sanitizer containing at least 60% alcohol.
  • Keep your hands away from your eyes, nose, and mouth. If you need to touch your face, make sure your hands are clean.
• Avoid touching dead bodies
  • Don’t participate in funeral activities that involve touching dead bodies, or touch items that have been in contact with dead bodies or have blood or body fluids on them.

After Travel

If you traveled and feel sick, particularly if you have a fever, talk to a healthcare provider and tell them about your travel. Avoid contact with other people while you are sick.