What is Marburg Virus Disease (MVD)?
As the world is facing COVID-19 and monkeypox outbreaks, World Health Organization (WHO) reported has recently reported two cases of Marburg virus disease (MVD) in the southern Ashanti region of Ghana. Unfortunately, both patients were deceased due to the infection and early contact tracing efforts demonstrated that the two cases may be unrelated. The samples collected from the two patients tested positive for Marburg virus and have been taken to the Institut Pasteur in Senegal for confirmatory analysis. If confirmed, the cases reported in Ghana are going to be the second time that Marburg virus disease (MVD) have been detected in West Africa, following a confirmed single case reported in Guinea on 16 September 2021. According to the Ghana Health Service, no new cases were reported since the collection of the samples, and 34 people who had contact with the two cases have been identified and are currently under quarantine. The high fatality rate and the lack of connection between the detected cases have deepened the concern about the extent and impact of possible outbreaks. Read along to learn more about Marburg virus disease (MVD), along with its symptoms, diagnosis, and treatment.
What causes Marburg Virus Disease (MVD)?
Formerly known as Marburg haemorrhagic fever, Marburg virus disease (MVD) is a severe illness caused by the Marburg virus (MARV) from the family Filoviridae, which also includes the six species of Ebola virus. Marburg virus (MARV) is a zootonic, enveloped, filamentous, negative single-stranded RNA virus which affects humans and non-human primates. Although it affects many cells, tissues and organs across the body, at the cellular level, Marburg virus (MARV) primarily targets macrophages and dendritic cells. At the organ level, lymphoid tissues and liver have been identified as main targets for the Marburg virus (MARV). Accordingly, World Health Organization (WHO) classifies Marburg virus (MARV) as a Risk Group 4 pathogen, which refers to pathogens that usually cause serious human and animal disease, transmit from person to person, and lack effective treatment.
How is Marburg virus (MARV) transmitted?
Animal-to-human transmission of Marburg virus (MARV) is primarily through exposure to Egyptian fruit bats (Rousettus aegyptiacus). Person-to-person transmission can be through direct contact either with the blood, secretions, organs and bodily fluids of infected people or with contaminated surfaces and objects. While transmission through transfusion or transplantation may be possible, no such case has yet been reported.
Is Marburg Virus Disease (MVD) new?
Although it is relatively rare, Marburg virus disease has been discovered decades ago. Marburg virus disease (MVD) was initially discovered and isolated in European researchers and laboratory workers in Germany and the former Yugoslavia working with samples from African green monkeys imported from Uganda. Since then, Marburg virus disease (MVD) has caused sporadic cases and outbreaks in South Africa (1975), Kenya (1980/1987), former Soviet Union (1988/1990), Democratic Republic of Congo (1998-2000), Angola (2004-2005), Netherlands (2008), United States (2008), Uganda (2007/2008/2012/2014/2017), and Guinea (2021).
Is Marburg Virus Disease (MVD) common?
Fortunately, Marburg virus disease is a rare illness in humans. Still, the African fruit bat, which is the primary reservoir of the Marburg virus disease, has a wide distribution across Africa. Thus, although mostly sporadically, infections with the Marburg virus typically occur typically in Africa. In fact, many outbreaks of the Marburg virus have affected workers in bat-infested mines in Africa. For instance, the outbreak that has occurred in Democratic Republic of Congo between 1998 and 2000, has predominantly affected workers at a gold mine in Durba, causing 154 cases and 128 deaths in total. The largest outbreak of the Marburg virus was recorded in the Uige Province of Angola between 2004 and 2005, with 252 reported cases and 227 deaths. Most cases that has occurred outside of Africa, including those reported in Netherlands and the US, were reported in travelers returning from Africa.
What are the signs and symptoms of Marburg Virus Disease (MVD)?
The first symptoms of Marburg virus disease (MVD) usually appear suddenly following an incubation period of 2-21 days. Early symptoms of the disease include fever, chills, severe headaches, myalgia, and joint aches. Around five days after the onset of symptoms a raised rash may appear along with more severe symptoms such as abdominal pain, nausea, vomiting, sore throat, chest pain, bruising, and bleeding (typically from the eyes). As the disease reaches its critical state, several organs are affected including the pancreas, liver and kidneys. During this phase, the patient may develop symptoms such as severe bleeding from eyes, ears, nose, or rectum, severe weight loss, jaundice, delirium, shock, and multi-organ dysfunction. In the preagonal state, Marburg virus disease (MVD) may lead to symptoms such as multi-organ failure, dementia, coma, seizures and internal bleeding. According to World Health Organization, the average case fatality rate for Marburg virus disease (MVD) is around 50%. However, case fatality rates have varied between 24% to 88% among outbreaks based on virus strain, case management, and access to medical care.
How is Marburg Virus Disease (MVD) diagnosed?
The early diagnosis of Marburg virus disease (MVD) is critical for the prevention of severe disease and death. As the signs and symptoms of Marburg virus disease can be similar to several diseases such as malaria, typhoid fever, dengue fever, and Ebola virus disease, its clinical diagnosis may be difficult. However, depending on the time of infection, there are many testing options available for the diagnosis of Marburg virus disease (MVD) such as reverse transcription-polymerase chain reaction (RT-PCR) tests, antigen tests, and serological tests. Tests employing molecular methods which target NP, L and GP genes has demonstrated high sensitivity, specificity, and overall accuracy in the diagnosis of Marburg virus disease (MVD). Moreover, since the GP gene was found to be strain-specific, tests targeting the GP gene be utilized to identify the specific strain responsible for the infection. Antigen testing, on the other hand, proves to be effective in the early stages of Marburg virus disease (MVD), when the viral load in blood and tissues are high. Finally, there are serological methods such as the antigen-capture enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence assay (IFA). Whereas the IgM-capture ELISA can detect IgM antibodies which indicate recent infection as early as 2–4 days after the onset of symptoms, IgG-capture ELISA can detect IgG antibodies indicating past infection 8–10 days after symptom onset.
How is Marburg Virus Disease (MVD) treated?
There is currently no specific treatment for Marburg virus disease. When combined with early diagnosis, supportive hospital therapy has been shown to improve survival and recovery. On the other hand, there are experimental treatments involving agents such as favipiravir, remdesivir, galidesivir, and ribavirin that have been tried on non-human primates and/or are currently in the early phases of clinical trials.