What Do We Know About Marburg Virus Disease?

The World Health Organization announced that Equatorial Guinea confirmed its first outbreak of Marburg virus disease, after one sample tested positive. Nine deaths and 16 suspected cases have also been linked to the outbreak.

There have previously been sporadic outbreaks of the virus throughout sub-Saharan Africa, and the rare case in travelers, mostly returning from African countries.

Currently, there is no vaccine or antiviral treatment for this hemorrhagic fever, which can cause severe illness and death.

Here is what the scientific community has learned so far about Marburg virus disease.

Taxonomy

Marburg virus disease affects both people and non-human primates, and is caused by a genetically unique animal-borne RNA virus of the filovirus family (the same family as the Ebola virus).

Cases

The first known human cases of Marburg virus disease were reported in 1967 in Marburg and Frankfurt, Germany, and in Belgrade, Yugoslavia (now Serbia), when laboratory workers handling African green monkeys imported from Uganda became ill, followed by several healthcare providers and family members, for a total of 31 cases, according to the CDC.

Subsequent larger outbreaks included 154 cases in the Democratic Republic of Congo in 1998-2000 and 252 cases in Angola in 2004-2005. In addition, 15 cases occurred in Uganda in 2012. In 2008, a U.S. traveler returned from Uganda and developed illness 4 days later. He fully recovered, and was retrospectively diagnosed with Marburg virus disease.

Before the outbreak in Equatorial Guinea, the most recent cases were a confirmed case in Guinea in August 2021 and two cases reported in Ghana in 2022.

Transmission

The reservoir host of Marburg virus is Rousettus aegyptiacus, the African fruit bat, a sighted cave-dwelling bat found across Africa. Fruit bats do not show signs of infection. It is currently unknown whether other species also host the virus.

Marburg virus is transmitted to people directly from fruit bats, through infected non-human primates that handled body fluids, and from infected humans or those who have died from the disease.

The virus spreads through contact with blood or body fluids (urine, saliva, sweat, feces, vomit, breast milk, amniotic fluid, and semen) through broken skin or mucous membranes in the eyes, nose, and mouth.

Objects and surfaces contaminated from a sick person are also infectious.

Incubation

According to the CDC, the incubation period for Marburg virus disease is 2 to 21 days.

Symptoms

Symptoms of Marburg virus disease come on suddenly, and include fever, chills, headache, and myalgia. Around day 5 of symptoms, a maculopapular rash, most prominent on the trunk, may occur.

Other symptoms may include nausea, vomiting, chest pain, sore throat, abdominal pain, and diarrhea. 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.

Many symptoms of Marburg are similar to malaria, typhoid fever, and other viral hemorrhagic fevers that may be endemic in the area (such as Lassa fever or Ebola), which makes it difficult to diagnose, particularly when an individual case is seen.

Fatality

According to the CDC, the fatality rate is 23% to 90%.

Treatment

There are no vaccines or antiviral treatments approved to treat Marburg virus disease. Supportive therapy should be used in the hospital, including 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.

A range of potential treatments, including blood products, immune therapies, and drug therapies, as well as candidate vaccines with phase I data are being evaluated by the Marburg virus vaccine consortium (MARVAC).

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