Ebola virus is a filamentous, enveloped, negative‑sense RNA virus in the family Filoviridae that causes Ebola virus disease, a severe and often fatal hemorrhagic fever in humans and nonhuman primates.
Explanation
Ebola virus belongs to the genus Ebolavirus, which includes several species such as Zaire ebolavirus, Sudan ebolavirus, Bundibugyo ebolavirus and Tai Forest ebolavirus. The virion is pleomorphic and filamentous with a single‑stranded, non‑segmented RNA genome about 19 kb in length. After entering host cells via macropinocytosis, the virus replicates in the cytoplasm and assembles at intracellular membranes. Infection triggers a strong but dysregulated host immune response. Viral proteins suppress interferon signalling, leading to uncontrolled viral replication, widespread tissue injury and a cascade of inflammatory mediators. Clinical manifestations include sudden onset of fever, malaise, gastrointestinal symptoms and bleeding diathesis. The case fatality rate varies by species and outbreak, ranging from about 25 % to over 70 %. Ebola virus was first recognized in 1976 during simultaneous outbreaks in the Democratic Republic of the Congo and Sudan. Since then, outbreaks have occurred intermittently in Central and West Africa. The virus is believed to be maintained in nature by fruit bats. Human infection is acquired through contact with blood or secretions of infected animals and spreads between people through direct contact with bodily fluids, contaminated surfaces or needle sticks. Control relies on early case detection, isolation, contact tracing and community education. Licensed vaccines and monoclonal antibody therapies against Zaire ebolavirus have improved outbreak responses.
Outbreaks and Transmission
The largest Ebola outbreak on record occurred between 2013 and 2016 in Guinea, Liberia and Sierra Leone, resulting in more than 28 000 cases and over 11 000 deaths. Subsequent outbreaks in the Democratic Republic of the Congo from 2018 to 2020 highlighted ongoing challenges in outbreak control. Health‑care workers are at high risk due to exposure to infectious fluids; strict infection prevention measures, including personal protective equipment and safe burial practices, are essential. Non‑human primates and duikers are susceptible to Ebola virus, but fruit bats are considered the likely reservoir. Reston ebolavirus has been detected in pigs and monkeys in Asia but has not caused human disease.
Ebola virus disease demonstrates how zoonotic viruses can emerge and cause severe human illness, underscoring the importance of surveillance, rapid diagnostics and coordinated public health responses.
Related Terms: Filovirus, Hemorrhagic fever, Marburg virus, Zoonosis, RNA virus