Ebola virus
Summary
Ebola virus is a filovirus causing severe viral hemorrhagic fever with high mortality rates (up to 90%). It is transmitted via direct contact with bodily fluids of infected humans or animals (fruit bats are the natural reservoir), and outbreaks occur primarily in sub-Saharan Africa. Clinical presentation includes fever, severe hemorrhage, GI symptoms, and multiorgan failure.
Detail
Ebola virus is an enveloped, negative-sense, single-stranded RNA virus belonging to the family Filoviridae. It causes Ebola virus disease (EVD), characterized by a severe systemic inflammatory response leading to vascular endothelial damage, coagulopathy (DIC), and multiorgan failure. Pathophysiology involves viral replication in dendritic cells and macrophages, massive cytokine release ('cytokine storm'), impaired adaptive immunity due to lymphocyte apoptosis, and increased vascular permeability leading to hemorrhage and hypovolemic shock.
Transmission occurs through direct contact with blood, secretions, organs, or other bodily fluids of infected people or animals (bats, non-human primates). Human-to-human transmission is common in healthcare and burial settings due to lack of proper PPE. The incubation period ranges from 2-21 days.
Clinical features include abrupt onset fever, severe headache, myalgia, followed by GI symptoms (vomiting, diarrhea), and progression to hemorrhagic manifestations (petechiae, ecchymoses, mucosal bleeding), hypotension, and multiorgan failure. Laboratory findings show thrombocytopenia, elevated liver enzymes, and coagulopathy.
Diagnosis is confirmed via RT-PCR detecting viral RNA. Management is primarily supportive care (fluid/electrolyte management, blood product support) as there is no specific antiviral cure, though monoclonal antibody therapies (e.g., Inmazeb - atoltivimab/maftivimab/odesivimab) and antivirals like remdesivir have shown some efficacy. An FDA-approved vaccine (Ervebo, rVSV-ZEBOV) exists for prevention in high-risk populations.
High-yield associations: filovirus family, biosafety level 4 pathogen, high case fatality rate, importance of infection control and PPE in outbreak settings, differentiate from other viral hemorrhagic fevers (Lassa, Marburg, dengue).
Sources
- First Aid for the USMLE Step 1
- Sherris Medical Microbiology
- CDC Ebola Virus Disease Guidelines
- Harrison's Principles of Internal Medicine
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