Ebola

Ebola
Name	Ebola virus disease
Field	Virology

Ebola is a severe viral hemorrhagic fever caused by viruses in the family Filoviridae. The disease produces high mortality in humans and nonhuman primates and has prompted coordinated responses by global institutions during outbreaks. Clinical management, surveillance, and vaccine development have involved multiple nations, pharmaceutical companies, and public health agencies.

Overview

Ebola is caused by single-stranded, negative-sense RNA viruses in the family Filoviridae associated with genus-level taxa that have caused epidemics in central and western Africa. The illness first gained international attention during outbreaks that required coordination among the World Health Organization, Centers for Disease Control and Prevention, Médecins Sans Frontières, and affected national ministries of health such as the Ministry of Health (Democratic Republic of the Congo) and Ministry of Health and Sanitation (Sierra Leone). Clinical severity ranges from nonspecific febrile illness to multi-organ failure. International responses have included emergency use authorization of therapeutics by regulatory authorities like the United States Food and Drug Administration and accelerated vaccine deployment coordinated with the Gavi, the Vaccine Alliance.

Virology and Mechanism

Ebola viruses are filamentous virions with a nucleocapsid that encapsidates the genomic RNA and an envelope derived from host membranes; structural and nonstructural proteins mediate replication, immune evasion, and cytopathicity. Key viral proteins include the glycoprotein that binds to host receptors, the polymerase complex that catalyzes replication, and accessory proteins that antagonize interferon responses studied in laboratories at institutions like the National Institutes of Health, Institut Pasteur, and University of Oxford. Viral entry mechanisms involve macropinocytosis and endosomal processing requiring host factors identified in studies at the Wellcome Trust-funded centers. Pathogenesis results from direct cytolysis, dysregulated innate immune activation, endothelial dysfunction, and coagulopathy—pathways investigated in translational research partnerships with hospitals such as University College Hospital, Ibadan and research centers like the London School of Hygiene & Tropical Medicine.

Transmission and Epidemiology

Zoonotic spillover from reservoir hosts, most strongly implicated in field and molecular studies of fruit bat species in Africa, initiates human outbreaks; field teams from organizations like the Wildlife Conservation Society and universities including Makerere University have contributed ecological data. Subsequent human-to-human transmission occurs via direct contact with blood, secretions, organs, or other bodily fluids of infected individuals and via contaminated fomites; infection control guidance has been promulgated by the World Health Organization and implemented in clinical settings such as Kenema Government Hospital during outbreaks. Nosocomial amplification has been documented in historical events involving healthcare facilities and burial practices in communities studied by anthropologists affiliated with Columbia University and Harvard University. Surveillance, contact tracing, and genomic epidemiology performed by laboratories like the European Centre for Disease Prevention and Control and the Africa Centres for Disease Control and Prevention inform outbreak control and reveal transmission chains.

Clinical Presentation and Diagnosis

Initial presentation typically includes sudden fever, fatigue, myalgia, headache, and sore throat, progressing to vomiting, diarrhea, rash, renal and hepatic impairment, and in some patients, hemorrhagic manifestations; clinical descriptions have been published in case series by clinical teams from Johns Hopkins University, Imperial College London, and regional referral centers. Diagnosis relies on nucleic acid amplification tests such as RT-PCR, antigen detection assays, and serology performed in high-containment laboratories like the National Institute for Communicable Diseases (South Africa) and reference laboratories supported by the Vaccine Trials Network. Differential diagnosis in endemic regions may include infections managed at hospitals such as Freetown Central Hospital and laboratories testing for Lassa fever, malaria, typhoid fever, and other febrile illnesses.

Treatment and Prevention

Supportive care—fluid resuscitation, electrolyte correction, oxygen therapy, and organ support—remains foundational and has been delivered in treatment centers run by organizations including Médecins Sans Frontières and national health systems. Specific therapeutics with evidence from randomized trials, such as monoclonal antibody regimens and antiviral agents authorized by regulators including the European Medicines Agency and United States Food and Drug Administration, have reduced mortality in recent outbreaks. Vaccination strategies using recombinant vesicular stomatitis virus–based vaccines and adenovirus-vectored vaccines developed by teams at institutions like the National Institute of Allergy and Infectious Diseases and companies such as Merck have been deployed in ring-vaccination campaigns supported by Gavi, the Vaccine Alliance and national immunization programs. Infection prevention and control measures, personal protective equipment protocols, safe burial practices, and community engagement guided by anthropological studies from institutions like University of Oxford and McGill University are critical to interrupt transmission.

History and Notable Outbreaks

Since the identification of filoviruses in the late 20th century, notable outbreaks have included events in areas administered by colonial and postcolonial health authorities, prompting multinational responses. Significant epidemics occurred in regions including the Democratic Republic of the Congo, Guinea, Liberia, and Sierra Leone, with the 2014–2016 West Africa epidemic involving extensive international mobilization by the World Health Organization, United Nations Mission for Ebola Emergency Response, and aid organizations. More recent outbreaks in eastern and central Africa have engaged national actors such as the Government of the Democratic Republic of the Congo and partner laboratories including the Pasteur Institute in Dakar. Investigations into virus ecology have involved collaborations among zoological institutions such as the Smithsonian Institution and conservation organizations like the International Union for Conservation of Nature.

Category:Viral diseases