Marburg virus disease (MVD) is a severe illness characterized by hemorrhagic fever, with a fatality rate that can reach up to 88%. This virus belongs to the same family as the Ebola virus. The disease was first identified in 1967 during simultaneous outbreaks in Marburg and Frankfurt, Germany, and Belgrade, Serbia. These outbreaks were linked to laboratory work involving African green monkeys (Cercopithecus aethiops) imported from Uganda.
Since then, additional outbreaks and sporadic cases have been reported in countries including Angola, the Democratic Republic of the Congo, Kenya, South Africa (in a person with a recent travel history to Zimbabwe), and Uganda. Notably, in 2008, two independent cases were reported in travelers who visited a cave inhabited by Rousettus bat colonies in Uganda.
Transmission Dynamics
Human infections with MVD typically arise from prolonged exposure to mines or caves inhabited by Rousettus bat colonies, which are considered natural reservoirs for the virus. Once an individual is infected, the virus can spread through human-to-human transmission via 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 caring for patients suspected or confirmed to have MVD, especially in the absence of strict infection control measures. Transmission can additionally occur through contaminated medical equipment or needle-stick injuries, which are associated with more severe disease and higher fatality rates.
Burial practices involving direct contact with the deceased can further facilitate transmission, as infected individuals remain contagious as long as the virus is present in their blood.
Symptoms of Marburg Virus Disease
The onset of Marburg virus disease is abrupt, with symptoms such as high fever, severe headache, and profound malaise emerging suddenly. Muscle aches and pains are prevalent, with severe watery diarrhea, abdominal pain, cramping, nausea, and vomiting typically beginning on the third day. Diarrhea can potentially last up to a week, and patients may present as “ghost-like,” exhibiting drawn features, deep-set eyes, expressionless faces, and extreme lethargy. A non-itchy rash may appear between 2 and 7 days after the onset of symptoms.
Many patients develop severe hemorrhagic symptoms within 7 days. Fatal cases often involve bleeding from multiple areas, with fresh blood in vomitus and feces being common. Bleeding from the nose, gums, and vagina, as well as spontaneous bleeding at venepuncture sites, can occur. During the severe phase of illness, patients often sustain high fevers. Central nervous system involvement may lead to confusion, irritability, and aggression, while orchitis (inflammation of the testicles) has been occasionally reported in the late phase (around 15 days).
In fatal cases, death typically occurs between 8 and 9 days after symptom onset, usually preceded by severe blood loss and shock.
Diagnosis of MVD
Diagnosing MVD can be challenging due to its symptom overlap with other infectious diseases such as malaria, typhoid fever, shigellosis, meningitis, and other viral hemorrhagic fevers. Confirmation of Marburg virus infection is achieved through various diagnostic methods, including:
- Antibody enzyme-linked immunosorbent assay (ELISA)
- Antigen detection tests
- Serum neutralization tests
- Reverse-transcriptase polymerase chain reaction (RT-PCR) assay
- Virus isolation by cell culture
Samples collected from patients pose an extreme biohazard risk, necessitating laboratory testing on non-inactivated samples to be conducted under maximum biological containment conditions.
Treatment and Vaccination Efforts
Currently, there are no approved vaccines or antiviral treatments specifically for MVD. Supportive care, including rehydration with oral or intravenous fluids and treatment of specific symptoms, can significantly improve survival rates. Various potential treatments, including blood products, immune therapies, and drug therapies, are currently being evaluated. Monoclonal antibodies and antiviral drugs like Remdesivir and Favipiravir, which have been tested for Ebola, may also be considered for MVD.
In May 2020, the European Medicines Agency authorized the use of two vaccines—Zabdeno (Ad26.ZEBOV) and Mvabea (MVA-BN-Filo)—against Ebola, which may offer some level of protection against MVD, though their efficacy in clinical trials has yet to be fully established.
Marburg Virus and Its Animal Hosts
Rousettus aegyptiacus bats are considered the natural hosts for the Marburg virus, capable of carrying the virus without displaying signs of illness. These bats are believed to be the primary source of infection for humans. Other animals, such as non-human primates, can also be infected and may play a role in the transmission cycle.
Marburg Virus Disease (MVD) remains a significant global health threat due to its high fatality rate and the severe nature of its symptoms. The disease’s transmission dynamics, involving both animal-to-human and human-to-human spread, underscore the importance of stringent infection control measures, especially in healthcare settings and during burial practices.
Despite the absence of specific antiviral treatments or vaccines, supportive care and early diagnosis are crucial in managing MVD. Continued research and international collaboration are essential to develop effective treatments and preventive measures. Public health education and awareness can also play a vital role in preventing outbreaks and protecting at-risk populations.
In summary, while MVD poses a severe health threat, ongoing efforts in research, healthcare, and public awareness are key to mitigating its impact and preventing future outbreaks.
