Ebola virus

Ebola virus
Name	Ebola virus
Taxon	Orthoebolavirus zairense
Order	Mononegavirales
Family	Filoviridae
Genus	Orthoebolavirus
Species	Orthoebolavirus zairense

Ebola virus. It is the causative agent of Ebola virus disease, a severe and often fatal illness in humans and other primates. The virus, first identified in 1976 near the Ebola River in the Democratic Republic of the Congo, is a member of the Filoviridae family. Outbreaks have occurred primarily in regions of Sub-Saharan Africa, posing significant public health challenges.

Overview

The virus is one of six known species within the genus Orthoebolavirus. It is responsible for the most frequent and deadly outbreaks of viral hemorrhagic fever, with case fatality rates historically ranging from 25% to 90%. The World Health Organization classifies it as a Risk Group 4 pathogen and a priority disease under its R&D Blueprint. Major responses to epidemics have involved coordinated efforts by organizations like the Centers for Disease Control and Prevention, Médecins Sans Frontières, and the International Red Cross and Red Crescent Movement.

Virology

The virion appears as long, filamentous particles under electron microscopy, characteristic of the Filoviridae family. Its genome consists of a single strand of negative-sense RNA encoding seven structural proteins, including the glycoprotein which mediates entry into host cells. Viral replication occurs in the cytoplasm of infected cells. Research into its molecular biology has been advanced by teams at institutions like the National Institutes of Health and the United States Army Medical Research Institute of Infectious Diseases. The related Marburg virus shares a similar genomic structure.

Transmission

The natural reservoir is believed to be fruit bats of the Pteropodidae family. The virus spills over into human populations through contact with infected animals, such as chimpanzees, gorillas, or forest antelopes. Human-to-human transmission occurs via direct contact with bodily fluids or contaminated surfaces from symptomatic individuals. High-risk exposure events often occur during traditional burial practices or within healthcare settings lacking adequate infection control, as documented in outbreaks in Guinea, Liberia, and Sierra Leone.

Symptoms and diagnosis

After an incubation period of 2 to 21 days, onset is sudden with symptoms including high fever, severe headache, muscle pain, and profound weakness. This often progresses to vomiting, diarrhea, rash, and impaired organ function, with some patients experiencing hemorrhage. Diagnosis is confirmed through laboratory tests such as reverse transcription polymerase chain reaction or antigen-capture enzyme-linked immunosorbent assay performed in high-containment laboratories. Differential diagnosis must rule out other febrile illnesses like malaria, typhoid fever, or Lassa fever.

Treatment and prevention

There is no proven antiviral treatment for the infection; care is primarily supportive, focusing on fluid resuscitation, electrolyte balance, and treating complicating infections. However, two monoclonal antibody treatments, Inmazeb and Ebanga, received approval from the U.S. Food and Drug Administration following trials during the Kivu Ebola epidemic. Prevention centers on outbreak control measures: rapid case identification, contact tracing, safe burials, and strict isolation protocols. The rVSV-ZEBOV vaccine, developed by Merck & Co., has proven highly effective and was deployed extensively in the Equateur province outbreak.

Outbreaks

The first recorded outbreaks occurred simultaneously in 1976 in Yambuku, Zaire and Nzara, South Sudan. The largest epidemic began in 2014 in West Africa, primarily affecting Guinea, Liberia, and Sierra Leone, and was declared a Public Health Emergency of International Concern by the World Health Organization. A subsequent major outbreak in the Kivu region of the Democratic Republic of the Congo from 2018 to 2020 was notably complex, occurring in an active conflict zone involving armed groups like the Allied Democratic Forces. Sporadic cases continue to emerge, as seen in Uganda and Equateur province.

Category:Filoviridae Category:Viral diseases Category:Biological hazards