Tuesday, Sep 26, 2023

Explained: Africa Reports 'Unprecedented' Marburg Virus Outbreaks, What's Marburg Virus, How Deadly Is It?

Explained: Africa Reports 'Unprecedented' Marburg Virus Outbreaks, What's Marburg Virus, How Deadly Is It?

The fatality rate of Marburg disease is around 50%. Case fatality rates have varied from 24% to 88% in past outbreaks depending on virus strain and case management, according to World Health Organization (WHO).

Bats are the primary animal carriers of Marburg virus
Bats are the primary animal carriers of Marburg virus Getty Images

Africa is currently witnessing two outbreaks of Marburg virus in Tanzania and Equatorial Guinea, putting the continent in uncharted territory. 

It is for the first time that two outbreaks of Marburg virus have occured at the same time, according to France 24. The Marburg virus is a relative of the Ebola virus.

However, unlike Ebola, there is no vaccine or established treatment for Marburg virus. It's a relatively rare disease with a particularly hig mortality rate. 

Here we explain what's the status of Marburg outbreaks in Tanzania and Equatorial Guinea, what are Marburg symptoms, and why the disease is so concerning.

What's Marburg virus, how does it spread?

The Marburg virus causes Marburg virus disease (MVD). The main animal host of Marburg is African fruit bat. 

The Marburg virus spreads through bodily fluids. It can spread from bats to humans via urine, faecal matter, or saliva of bats, and can spread among humans through saliva, urine, faecal matter, semen, vomit, breast milk, etc. It has a particularly high mortality rate.

"The average MVD case fatality rate is around 50 per cent. Case fatality rates have varied from 24 per cent to 88 per cent in past outbreaks depending on virus strain and case management," says World Health Organization (WHO).

Infection among humans can spready from direct contact with bodily fluid as wella as indirect contact with a surface contaminated with bodily fluid of the infected person, notes Medical News Today (MNT). This means that immediate family members and healthcare personnel are at the highest risk of human-to-human infection.

Historically, the people at highest risk for contracting MVD include family members and hospital staff who care for patients carrying Marburg virus and have not used proper infection prevention and control measures, said  Dr. Jonathan Towner of the US Centers for Disease Control and Prevention's (CDC) Viral Special Pathogens Branch.

He further told MNT, "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,” he told MNT. “Exposure risk can be higher for those travelers visiting endemic regions in Africa who have contact with or come close proximity to Egyptian rousette bats present in caves or mines where these bats typically live."

Primarily, the cause of infection is understood to be prolonged exposure to caves or mines where disease-carrying bats are present. They can transfer the disease through prolonged exposure to humans present there. However, experts say that Marburg does not spread as quickly as SARS-CoV-2, the virus that causes Covid-19 disease.

The Marburg virus is 'much less easily transmissible than Covid-19', said Cesar Munoz-Fontela, a specialist in tropical infectious diseases at the Bernhard Nocht Institute for Tropical Medicine, Hamburg. Citing Munoz-Fontela, France 24 further reported that while the coronavirus spreads by respiratory droplets –with coughing and sneezing spreading it into the air– transmission of Marburg requires contact with the bodily fluids of an infected person.

Moreover, asymptomatic transmission is not possible in case of Marburg virus, notes France 24.

"Marburg only starts to become contagious at the same time symptoms start appearing, between two and 21 days after the virus has been contracted. So there is zero risk of undetected transmission by asymptomatic carriers," notes France 24.

What are Marburg symptoms, how is it treated?

The Marburg symptoms include fever, chills, sore throat, and diarrhea, among other symptoms. 

MNT notes that it might take 2-21 days for the symptoms to appear. It lists the following symptoms:

  • fever and/or chills
  • headache
  • muscle aches and pains
  • nausea and/or vomiting
  • sore throat
  • diarrhea
  • non-itchy rash on the chest, back, and/or stomach
  • hemorrhagic-related issues, including bleeding nose, gums, on the skin, and/or in the eyes

The WHO notes that Marburg disease can start abruptly with severe headache and high fever.

The WHO says, "Illness caused by Marburg virus begins abruptly, with high fever, severe headache and severe malaise. Muscle aches and pains are a common feature. Severe watery diarrhoea, abdominal pain and cramping, nausea and vomiting can begin on the third day. Diarrhoea can persist for a week."

The confirmation of Marburg disease could be tricky with symptoms alone so diagnostic tests are required. The WHO says, "It can be difficult to clinically distinguish MVD from other infectious diseases such as malaria, typhoid fever, shigellosis, meningitis and other viral haemorrhagic fevers."

The WHO lists the following tests for confirming Marburg disease:

  • antibody-capture enzyme-linked immunosorbent assay (ELISA)
  • antigen-capture detection tests
  • serum neutralization test
  • RT-PCR assay
  • electron microscopy
  • virus isolation by cell culture

There are currently no specific Marburg vaccines or treatments. The treatment for Marburg patients is therefore based on their symptoms. 

"Right now, healthcare professionals treat the different symptoms of MVD as they emerge. And if hospitalized, doctors treat patients with MVD with supportive therapies such as rehydration and replacing blood loss through hemorrhagic-related symptoms," says MNT, adding that certain drugs have shown potential in studies of working on Marburg, such as favipiravir.

Marburg virus outbreak in Africa

It is for the first time that two Marburg virus outbreaks have happened at the same time in Africa, according to France 24.

Currently, Tanzania and Equatorial Guinea have Marburg outbreaks. The one in Equatorial Guinea is particularly concerning because of the high fatality rate.

Equatorial Guinea declared a Marburg outbreak on February 13 and Tanzania confirmed the outbreak on March 21, according to US CDC.

As of April 6, five of eight confirmed Marburg patients died in Tanzania, as per CDC. The situation in Equatorial Guinea is more worrying as 11 of 15 patients have so far died, as per France 24, which adds taht the WHO has concerns that official tallies do not reflect the true extent of the outbreak.

"This is a problem – this unprecedented outbreak of the Marburg virus in two different countries," said Paul Hunter, an epidemiologist at the University of East Anglia to France 24.

"There has been an acceleration in the number of Marburg virus outbreaks over recent years," said Munoz-Fontela, quoted above.

The current outbreaks are particularly concerning as outbreaks until now have been small and singular except for two big outreaks that have led to grim figure of 50 per cent average fatality rate.

"Between 1998 and 2000, 128 patients died out of a total of 154 confirmed cases in DR Congo. Four years later, Marburg struck Angola, killing 227 out of 252 infected patients," notes France 24.

The number of outbreaks has also increased in recent years, which has been credited partially to the encroachment of forests and closer human-bat cohabitation. The outberaks are further worsened by the fact that there is no vaccine for the disease yet.

Dr. Patrick Kuma-Aboagye, Director-General of Ghana Health Service, said that the risk of bat-to-human transmission can be reduced by keeping away from caves and mines with large bat populations. Additionally, he said, any animal products should be thoroughly cooked before eating them, as per MNT.

She told MNT, "Avoid prolonged exposure to mines or caves inhabited by fruit bat colonies. Avoid direct or close contact with infected patients, particularly with their body fluids. (And) thoroughly cook all animal products (blood and meat) very well before consumption."


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