Marburg virus: a potential outbreak on the horizon?

Abstract

Dear Editor, Marburg virus, formerly known as Malburg hemorrhagic fever, is a member of the filovirus family, and belongs to the genus Marburgvirus1. This virus has been a source of concern since 1967, with 2 further massive outbreaks recorded in the years 1998 and 20042. Past research on the laboratory findings of Marburg virus disease (MVD) has determined that the primary target of this filovirus is mononuclear phagocytes, alongside other epithelial cells found within various organs2. In addition, the mode of transmission predominantly involves the infection via mucosal surfaces, breaks in the skin (wounds), or parenteral exposure3. With recent findings, it has been observed that an African species of fruit fly (Roussettus aegypticus) may be a reservoir for the Marburg virus, though transmission via bat excrement is usually considered the commonest method of Marburg’s induction into the human population4. MVD is considered to be exceedingly fatal in nature, with fatality rates rising up to 90% in infected individuals5. Due to the limited data available, the exact pathogenesis, clinical manifestations, and disease progression remain debatable. However, observations from the previous outbreaks have given several indications of its characteristic features, including the incubation period ranging from 2 to 21 days, alongside the clinical symptoms of high fever, malaise, vomiting, diarrhea, dermatologic manifestations, and more3. In severe cases, mucosal bleeding and hemorrhage have been observed. The MVD has been said to produce Ebola-like symptoms, indicating the lethality of this infection. The current sources of concern include the recent outbreaks in Tanzania and Equatorial Guinea. In Tanzania, the first case was detected in March 2023, and resulted in the death of 5 patients, including a health care worker2,6. Although the number of cases being detected has been declining, it is important to consider the possibly extended incubation period and undiagnosed cases of infection that may be unaccounted for. Moreover, the lack of transparency of the current outbreak situation in Equatorial Guinea, as well as the unbarred borders leading to Cameroon and Gabon, make the situation in this country incredibly concerning, as per the World Health Organization (WHO)6. Historically, no outbreaks have occurred since the 2004–2005 Angolan outbreak, other than isolated cases across the world. This was the most fatal outbreak ever known, with up to 227 deaths and a frightful fatality rate of 90%2,6. The first ever outbreak was detected in 1967 in Marburg, Germany, followed by an outbreak in South Africa in 1975, among other smaller outbreaks in Kenya and Russia2. A deadly outbreak of the Malburg virus can be severely detrimental for the world. Presently, there is no treatment or cure for MVD, and the absence of an approved vaccine formulation7. Current treatment guidelines revolve around the use of supportive hospital therapy, with respect to maintenance of fluids and electrolytes, oxygen saturation, blood pressure, and treatment of complicating infections7. There are several vaccinations under development, currently being tested through non-human trials. However, a phase 1, open-label, clinical trial was performed on human participants, utilizing the cAd3-Marburg on healthy participants8. The trial observed mild to moderate reactogenicity with commonly mild symptoms post-vaccination, including tenderness at the site of injection, headache, and myalgia8. Up to 95% of the sample produced a glycoprotein-specific antibody response against the administered antigen, demonstrating the favorable efficacy observed with the use of this vaccine8. However, comprehensive randomized controlled trials, with larger population groups, are required to arrive at a robust conclusion. It is recommended to utilize the current outbreaks as an opportunity to conduct trials and determine the prophylactic activity of the vaccinations under development. The vaccine developers are urged to boost production and transport the products to countries currently suffering/likely to suffer from an outbreak of the Malburg virus, to conduct comprehensive studies, to further our understanding of this disease. Surveillance systems should be strengthened by training healthcare workers to quickly recognize MVD symptoms, report suspected cases promptly, and establish a system for laboratory testing and case confirmation. In addition, the resource and funding scarcity within developing countries can further intensify the burden of a Malburg outbreak, as observed with the COVID-19 pandemic. This necessitates an immediate intervention from international health organizations, such as the WHO. In conclusion, the Malburg virus is an extremely lethal agent, with incredible virulence and pathogenicity2, paired with high fatality rates as observed in previous outbreaks. Nations possessing an increased risk of Malburg viral outbreaks (eg, those bordering Tanzania or Equatorial Guinea) are recommended to employ precautionary measures and increase transparency in the information regarding the chain of infections. Moreover, researchers are urged to conduct further studies on the possible preventative and treatment measures against MVD. Finally, it is imperative that global health authorities take swift action to prevent a Marburg virus outbreak, and mitigate the potential for a global health crisis. The time to act is now. Ethical approval None. Consent None. Sources of funding None. Author contribution Conceptualization: M.O.L.; Literature Search: M.O.L, M.I.S.; Creation of First Draft: M.O.L., M.I.S., M.A.I., S.A.S. and M.S.; Creation and review of final draft: M.O.L. and M.I.S. All authors have approved the final manuscript. Conflicts of interest disclosure The authors declare that they have no financial conflict of interest with regard to the content of this report. Research registration unique identifying number (UIN) Not Applicable. Guarantor Muhammad Omar Larik. Assistance with the study None. Provenance and peer review Not commissioned, externally peer-reviewed.