Ebola and Marburg haemorrhagic fever viruses: major scientific advances, but a relatively minor public health threat for Africa

Abstract

Ebola and Marburg viruses are the only members of the Filoviridae family (order Mononegavirales), a group of viruses characterized by a linear, non-segmented, single-strand negative RNA genome. They are among the most virulent pathogens for humans and great apes, causing acute haemorrhagic fever and death within a matter of days. Since their discovery 50 years ago, filoviruses have caused only a few outbreaks, with 2317 clinical cases and 1671 confirmed deaths, which is negligible compared with the devastation caused by malnutrition and other infectious diseases prevalent in Africa (malaria, cholera, AIDS, dengue, tuberculosis …). Yet considerable human and financial resourses have been devoted to research on these viruses during the past two decades, partly because of their potential use as bioweapons. As a result, our understanding of the ecology, host interactions, and control of these viruses has improved considerably.

Describing readmissions to an Ebola case management centre (CMC), Sierra Leone, 2014

“…Readmissions can only develop from the pool of discharged non-cases because EVD positive cases have immunity to the specific strain if they survive to discharge [11,12]. On further inspection of the epidemiological curve it appears that positive readmissions have clustered following peaks in primary admissions.…”

Management of pregnant women infected with Ebola virus in a treatment centre in Guinea, June 2014

“…Patients with EVD generally present with a history of contact with another person with EVD and an abrupt onset of a nonspecific febrile syndrome. A systemic inflammatory response can cause multiple organ failure and shock [3,4]. Pregnant women are reported to be at higher risk to die [5].…”

Determination of Specific Antibody Responses to the Six Species of Ebola and Marburg Viruses by Multiplexed Protein Microarrays

“…he first recorded outbreak of Marburg virus (MARV) took place in 1967 in Germany and Yugoslavia and was traced to infected African green monkeys from Uganda (1), while the first outbreaks of Ebola virus were documented in Sudan and the Democratic Republic of Congo in 1976 (2,3). Cycles of filovirus outbreaks continue to be a major concern from a biodefense and public health perspective as no licensed therapeutic agents or vaccines are available.…”

“…Following an incubation period that can range from 2 to 21 days, infected patients commonly develop nonspecific flulike symptoms of fever, vomiting, loss of appetite, headache, abdominal pain, fatigue, and diarrhea, while bleeding occurs in a smaller number of infections (1,3,5). Case fatalities are associated with reduced adaptive immune responses (6,7) and the release of high levels of immune response mediators (8)(9)(10)) that contribute to vascular dysfunction, coagulation disorders, shock, and eventual multiorgan failure (2).…”

“…Serological assays based on recombinant filovirus antigens are alternatives that do not require infectious agents, and several ELISAs were reported (14)(15)(16)(17)(18). For example, Nakayama and coworkers developed a glycoprotein (GP)-based ELISA representative of all six species of filoviruses and analyzed human patient sera from Ebola and Marburg virus outbreaks (15 (2). Further complicating assay development, the single-stranded, negativesensed RNA genome (ϳ19 kb) encodes seven structural proteins (1,19,20) that are all potential antigens: the nucleoprotein (NP), virion protein 35 (VP35), VP40, glycoprotein (GP), VP30, VP24, and RNA-dependent RNA polymerase (L).…”