Marburg virus is one of the most life-threatening viruses that causes Marburg virus disease. It belongs to the family Filoviridae, which includes highly infectious, severe, and deadly viruses. Marburg virus can cause extreme bleeding and fever, multiple organ failure, and death in humans.¹ Due to the Marburg virus’s  ability to pose a deadly threat to individuals and to the community, the World Health Organisation classifies it as a group 4 disease-causing agent.²

Marburg virus was first detected in 1967 in Marburg and Frankfurt, Germany, and the former Yugoslavia. To date, there have been about 20 Marburg virus outbreaks. Marburg virus outbreaks have been reported in some African countries, such as the United Republic of Tanzania, Guinea, Equatorial Guinea, and Ghana, with a recent outbreak confirmed in Rwanda on the 27th of September, 2024. Countries with high infection rates of individuals were seen in the Democratic Republic of Congo and Angola, making the Marburg virus a public health challenge.^3,4

It is challenging to precisely detect Marburg virus infection in its early stages because its signs and symptoms are very much like those of Ebola virus and other viral infections that cause bleeding and fever, thus making Marburg virus infection diagnosis complicated.⁵ The rise and recurrence of the Marburg virus are likely due to the geographical spread of bats, which are the main host, environmental factors, and human actions.³

Source of the marburg virus 

Bats, particularly the fruit bat Rousettus aegyptiacus, are the host of the Marburg virus.⁶

Some species of bats, like the Chiroptera and Sundevall's leaf bats, may also be hosts to the Marburg virus. In addition, the possibility of transmission to humans increases when humans come into contact with infected primates. Primates are considered the middle hosts because they are prone to virus infections. This virus multiplies within them and can be transmitted to humans and other animals.⁷

How is the marburg virus transmitted?

In bats, the Marburg virus can be transmitted to other bats through bites,⁸ mating,⁹ or through ticks and insects. Current research indicates that a form of the Marburg virus was found in the mouth, anus, urine, and blood samples of infected bats.¹⁰

How do humans get infected with the Marburg virus?

Humans get infected mainly by contact with the Marburg virus either directly or indirectly.

Direct contact occurs when 

• The blood, tissues, and other bodily secretions such as tears, saliva, urine, fetal fluids, breast milk, and excreta of an infected person, primate, or bat come into contact with the broken skin or mucous membrane of an individual^1,11 
• Organ transplant¹²
• Transmission from mother to her unborn child through the placenta¹³
• Sexual transmission¹⁴

Indirect contact occurs when a person comes into contact with contaminated non-living objects such as clothes, utensils, medical instruments, surfaces, and bed covers.¹¹

Victoria marburg, a type of marburg virus, can live on liquids and solids for more than 21 days at cold temperatures.¹⁵

How the body responds when infected with the marburg virus 

When the Marburg virus enters the body, it targets the monocytes, macrophages, and dendritic cells. 

When the dendritic cells are infected, it disrupts the innate immune response and costimulation of the lymphocyte. 

Infection of the macrophage causes a malfunction of the lymphocyte apoptosis (programmed cell death of lymphocytes), which reduces the lymphocyte cells in the spleen, thymus, lymph node, and liver leading to a weak immune system and an increased level of cytokines and TNF-α (tumour necrosis factor alpha), leading to lymphopenia (abnormal low amount of white blood cells) and reduced immune response. The presence of IL-6 (Interleukin-6) and TNF-α leads to changes in blood vessel permeability. 

Also, infection of the macrophages produces tissue factor (TF) which, when combined with the Infected liver hepatocytes, causes abnormal blood clotting throughout the body, such as  disseminated intravascular coagulation (DIC) 

 In the adrenal gland, the adrenocortical cells (which produce hormones that are important to maintain normal body functions) are damaged, resulting in hypovolemia (low blood volume) and hypotension (abnormally low blood pressure), ultimately resulting in multi-organ failure and death.^5,16

Who is most at risk of contracting the marburg virus?

Individuals with the highest risk of contracting the Marburg virus are:^6,17,18,19

• Family members, caregivers, and healthcare workers who are in close contact with people infected with the Marburg virus. The risk of infection increases when preventive and control guidelines are not followed
• Veterinarians 
• Laboratory workers who come in contact with infected primates or are exposed during laboratory accidents
• Embalmers and cemetery workers, including persons who participate in burial rites that involve close contact with the deceased's body. A corpse infected with the Marburg virus is still infectious as long as the Marburg virus is still in the bloodstream
• Miners and tourists who come in contact with the infected fruit bat caves
• Unborn children of infected mothers

What are the signs and symptoms of the marburg virus?

Bats infected with the Marburg virus do not show any outward signs or symptoms of infection.²⁰ However, when humans get exposed to the Marburg virus, it takes about 2 to 21 days for them to begin to see signs and symptoms, with an average of 5 to 10 days in humans (incubation period). ¹⁷

The signs and symptoms of the Marburg virus vary from mild to severe depending on the progression of the disease.

Mild symptoms that appear within days 1 to 5 after the incubation period include:^2,5

• Sore throat
• Increased body temperature
• Chest pain
• Nausea
• Vomiting
• Shivering and feeling very cold
• Diarrhoea
• Abdominal pain
• Muscle aches and pain

After the 5th day, symptoms become severe because vital organs, such as the liver, kidneys, heart, lungs, brain, and small intestine, start failing and are not able to carry out a majority of their functions. It's at this point that the organs are close to failing. 

Some of the severe symptoms that happen between days 5 to 13, in addition to the previous symptoms, include:^2,5,21

• Jaundice
• Impaired mental state
• Extreme weight loss
• Severe low blood volume  (Hypovolemic shock)
• Severe widespread bleeding (systemic haemorrhage) is seen in mucous membranes, in mucous membranes, stools, vomit, sites of vein puncture, and skin.
• Rash that looks flat or rough (maculopapular rash) all over the body.  
• Ongoing fever 
• Conjunctivitis, also known as pink eye
• Abnormal enlargement of lymph nodes
• Abnormally low count of white blood cells and platelets
• Shortness of breath
• Swelling (oedema) of organs like the brain, heart, and kidneys
• Increase in enzymes like Alanine Transaminase, Aspartate Transaminase, and blood creatinine, which indicate kidney, liver, and pancreas damage
• Inflammation of the brain is also known as encephalitis

Symptoms observed on days 13 to 20 include:^2,5

• Extreme dehydration
• Convulsion
• Tissue death initially affects the liver and lymphatic system and continues to affect the male and female reproductive systems, thyroid, pancreas, kidney, adrenal gland, and skin.
• Abnormal blood clotting in all blood vessels, such as disseminated intravascular coagulation (DIC) 

Some patients may experience additional health issues during and after recovering from the Marburg virus disease. They include:¹⁶

• Arthritis or arthralgia
• Psychosis
• Eye disease
• Exhaustion
• An infected pregnant mother who either loses her baby via miscarriage or after birth. 
• Hepatitis 

How is the marburg virus treated?

Currently, there is no approved vaccine or treatment for the Marburg virus; instead, symptoms are managed, and palliative care is provided to address the imbalance in the body's function to avoid more complications or death.

Some management strategies include:²²

• Managing pain
• Replenishing  lost fluids and essential minerals like sodium, potassium, and calcium due to dehydration
• Balancing  oxygen levels and blood pressure
• Treating any additional health issues or complications during or after the Marburg virus disease

Summary

Marburg virus is a highly infectious and fatal virus that weakens and destroys the body’s immune system, resulting in severe bleeding, very high fever, and several organ failures  (haemorrhagic fever). Egyptian bats are the chief host of the Marburg virus. 

Marburg virus is transmitted to humans when their broken skin or mucous membrane comes in contact with the bodily fluids of infected bats, primates, humans, or corpses. A person getting better from the Marburg virus is still infectious. The risk of transmission increases when one touches contaminated non-living surfaces, materials, or objects. There is a high risk of becoming infected with the Marburg virus if the person is a healthcare worker, caregiver, family member, veterinarian, laboratory worker, miner, tourist, embalmer, cemetery worker, or an unborn child of an infected mother. 

Currently, there is no endorsed treatment or vaccine for the Marburg virus. However, managing symptoms and providing palliative care in response to the imbalance in normal bodily functions will help to avoid the risk of more complications or death.