Key Facts About Marburg Virus Disease (MVD)

Marburg virus disease (MVD), previously known as Marburg hemorrhagic fever, is a severe and often fatal illness in humans. With an average case fatality rate of around 50%, MVD poses a significant public health threat, with rates varying from 24% to 88% during past outbreaks. Early supportive care, including rehydration and symptomatic treatment, can improve survival rates. Currently, there are no approved vaccines or antiviral treatments for MVD, but various candidates are under development. The natural host of the Marburg virus is the Rousettus aegyptiacus, a fruit bat species belonging to the Pteropodidae family. The virus is transmitted to humans through contact with these bats and spreads among humans via direct contact with infected bodily fluids. Community engagement is crucial for successfully controlling outbreaks.

Overview

Marburg virus (MARV) and Ravn virus (RAVV), both classified under the species Orthomarburgvirus marburgense, are the causative agents of MVD. The disease was first identified in 1967 during simultaneous outbreaks in Marburg and Frankfurt, Germany, and Belgrade, Serbia, linked to laboratory work with African green monkeys imported from Uganda. Since then, sporadic cases and outbreaks have been reported in several African countries, including Angola, the Democratic Republic of the Congo, and Uganda. Notably, in 2008, two independent cases were linked to caves inhabited by Rousettus aegyptiacus bats in Uganda.

Transmission

Human infection with MVD typically begins with prolonged exposure to mines or caves where Rousettus fruit bats reside. Once the virus enters the human population, it spreads through direct contact with the blood, secretions, organs, or other bodily fluids of infected individuals. Contaminated surfaces and materials, such as bedding and clothing, can also facilitate transmission. Healthcare workers are particularly at risk when treating patients without strict adherence to infection control protocols. Burial ceremonies involving direct contact with deceased individuals can further propagate the virus. Importantly, individuals are not contagious until they exhibit symptoms, and they remain infectious as long as the virus is present in their blood.

Symptoms of Marburg Virus Disease

The incubation period for MVD ranges from 2 to 21 days. The disease typically begins abruptly, presenting with high fever, severe headache, and malaise. Muscle aches, severe watery diarrhea, abdominal pain, nausea, and vomiting may develop by the third day. A non-itchy rash can appear between 2 and 7 days after symptom onset. By day 5, patients may experience hemorrhagic manifestations, including blood in vomit and feces, as well as bleeding from the nose, gums, and vagina. Neurological symptoms such as confusion and irritability may also occur. In fatal cases, death usually occurs between 8 and 9 days after symptom onset, often preceded by severe blood loss and shock.

Diagnosis

Diagnosing MVD can be challenging due to its similarity to other infectious diseases, such as malaria and typhoid fever. Confirmation of Marburg virus infection is achieved through various diagnostic methods, including:

• Antibody-capture enzyme-linked immunosorbent assay (ELISA)
• Antigen-capture detection tests
• Reverse transcriptase polymerase chain reaction (RT-PCR) assay
• Virus isolation via cell culture in maximum containment laboratories

Due to the extreme biohazard risk posed by samples collected from patients, laboratory testing must be conducted under strict biosecurity measures.

Treatment and Vaccines

Currently, there are no approved vaccines or antiviral treatments for MVD. However, early intensive supportive care, including rehydration and symptom management, can significantly improve survival rates. Several candidate monoclonal antibodies and antiviral therapies, along with potential vaccines, are being evaluated in clinical trials.

Marburg Virus in Animals

Rousettus aegyptiacus bats are recognized as the natural hosts of the Marburg virus, showing no apparent disease. The geographic distribution of the virus often overlaps with the habitats of these bats. The initial outbreak in 1967 was linked to African green monkeys imported from Uganda. Experimental studies have indicated that pigs may also be susceptible to filovirus infections, suggesting they could act as potential amplifiers during outbreaks.

Prevention and Control

Effective outbreak control relies on community engagement and a multifaceted approach, including case management, surveillance, contact tracing, and infection prevention in healthcare settings. Raising awareness about risk factors and protective measures is essential for reducing transmission. Key prevention strategies include:

• Avoiding prolonged exposure to bat-inhabited areas.
• Wearing protective clothing when in contact with potentially infected animals.
• Isolating suspected or confirmed MVD patients in designated treatment centers.
• Ensuring safe and dignified burial practices for deceased individuals.

Controlling Infection in Healthcare Settings

Healthcare workers must adhere to standard precautions when caring for patients, regardless of their diagnosis. This includes basic hand hygiene, respiratory hygiene, and the use of personal protective equipment. Additional infection control measures are necessary when treating suspected or confirmed MVD patients to prevent contact with infectious materials.

Care for MVD Survivors

Survivors of MVD require compassion and support as they may experience both clinical and psychological sequelae. The World Health Organization (WHO) does not recommend isolating convalescent patients whose blood tests negative for the virus. However, the virus can persist in immune-privileged sites, such as the testicles and eyes, leading to potential transmission through semen. A semen testing program is recommended for male survivors to monitor and mitigate the risk of transmission.

WHO Response

The WHO aims to prevent MVD outbreaks through surveillance and support for at-risk countries in developing preparedness plans. In the event of an outbreak, the WHO provides assistance in surveillance, community engagement, case management, laboratory services, and safe burial practices.

Chronology of Major Marburg Virus Disease Outbreaks

In conclusion, Marburg virus disease remains a critical public health challenge, particularly in regions where outbreaks have occurred. Continued research, community engagement, and robust healthcare responses are essential to mitigate the impact of this deadly virus.