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Marburg virus: how it is spread and what are its symptoms

The Marburg virus is included on the World Health Organization’s list of priority pathogens capable of causing future pandemics, along with Covid-19, Crimean-Congo hemorrhagic fever, Ebola, Lassa fever, respiratory syndrome Middle East Disease (MERS) and severe acute respiratory syndrome (SARS), Nipah virus disease and henipavirus infections, Rift Valley fever or Zika. The goal of this list is “to pinpoint the pathogens that researchers around the world need to invest money and energy in to develop tests, treatments and vaccines,” as Dr. Soumya Swaminathan, WHO’s scientific director, points out.

Marburg virus disease (MVD) was first identified in 1967 after simultaneous outbreaks were recorded in Marburg (hence its name) and Frankfurt (Germany) and in Belgrade (Serbia). Subsequently, outbreaks and sporadic cases have been reported in Angola, Kenya, the Democratic Republic of the Congo, South Africa and Uganda, but this is the first time it has been detected in Equatorial Guinea.

The Marburg virus is transmitted to humans through fruit bats and spreads in humans through direct contact with the body fluids of infected people, or with surfaces and materials.

It has an incubation period of between 5 and 10 days where it is not transmitted, it causes a febrile hemorrhagic disease that begins suddenly with fever, muscle pain, weakness, headache and odynophagia. In fact, in 50-80 percent of patients, rapid weakening accompanied by gastrointestinal symptoms, abdominal discomfort, severe nausea, vomiting and diarrhea occurs within 2 to 5 days.

The intensity of the disease increases after 5-7 days with a maculopapular rash and hemorrhagic symptoms such as petechiae, mucosal and gastrointestinal bleeding. Additionally, neurological symptoms (disorientation, seizure, and coma) may occur in later stages of the disease.

The beginning of transmissibility is related to viremia and the appearance of the first symptoms, although during the incubation period, in which infected people are asymptomatic, the virus is not detected in blood or body fluids, therefore that the virus is not transmitted. Therefore, transmissibility begins when symptoms develop and persists as long as there is virus in the blood.

This disease is very virulent, in fact its fatality rate, according to the WHO, is 88%. In the worst phase of the disease, the WHO details that “patients present a ‘ghost-like appearance’ due to sunken eyes, facial inexpression and extreme lethargy.”

Currently, there are no vaccines or antiviral treatments approved to treat the virus. The only thing that has been shown is that supportive therapy with intravenous fluids, supplemental oxygen, electrolytes, etc., can significantly improve clinical outcome.

However, some pharmaceutical products such as immunotherapeutics, interferons or antivirals are being developed to combat the disease. Specifically, antivirals such as faviparavir and remdesivir appear to be advantageous in non-human primates, but there is still no clear evidence of their benefit in humans.

There is also no authorized vaccine, although the European Medicines Agency (EMA) has authorized the ‘Zabdeno’ and ‘Mvabea’ vaccines for post-exposure prophylaxis of Ebola virus disease.