Ebola virus disease

Ebola virus disease
Name	Ebola virus disease
Synonyms	Ebola hemorrhagic fever, Ebola
Caption	Colorized scanning electron micrograph of Ebola virus particles (blue) on a Vero cell (yellow).
Field	Infectious disease
Symptoms	Fever, sore throat, muscle pain, headaches, vomiting, diarrhea, rash, bleeding
Complications	Multiple organ failure, septic shock
Onset	2 to 21 days after exposure
Duration	Variable
Causes	Ebolaviruses
Risks	Contact with infected bodily fluids, bushmeat
Diagnosis	Blood tests for viral RNA, antibodies, or the virus itself
Differential	Malaria, cholera, typhoid fever, meningitis, other viral hemorrhagic fevers
Prevention	Infection control, personal protective equipment, safe burial practices, vaccines (e.g., rVSV-ZEBOV)
Treatment	Supportive care (intravenous fluids, blood transfusions), investigational drugs (e.g., Inmazeb, Ebanga)
Prognosis	High case fatality rate (25–90%)
Frequency	Outbreaks occur sporadically in sub-Saharan Africa
Deaths	>15,000 recorded (since 1976)

Ebola virus disease. It is a severe, often fatal illness in humans caused by infection with viruses of the genus *Ebolavirus*. The disease first emerged in 1976 in simultaneous outbreaks in Nzara, Sudan, and near the Ebola River in the Democratic Republic of Congo, which provided its name. The World Health Organization lists it as a priority disease due to its epidemic potential and high case fatality rate.

Signs and symptoms

The incubation period ranges from 2 to 21 days. Initial symptoms are often non-specific and include sudden onset of fever, profound fatigue, muscle pain, headache, and sore throat. This is frequently followed by vomiting, diarrhea, rash, and impaired kidney and liver function. In some cases, patients develop both internal and external hemorrhagic manifestations, such as bleeding gums or blood in stool. The severe viremia and immune response can lead to cytokine storm, disseminated intravascular coagulation, and ultimately multiple organ dysfunction syndrome.

Transmission

The virus spreads through direct contact with the bodily fluids of a person who is symptomatic or has died from the disease. Bodily fluids include blood, vomit, feces, saliva, sweat, breast milk, amniotic fluid, semen, and vaginal fluid. Transmission can occur through broken skin or mucous membranes. The natural reservoir host is believed to be fruit bats of the Pteropodidae family, and the virus can be introduced into the human population through contact with infected animals, such as chimpanzees, gorillas, or through the hunting and preparation of bushmeat. The virus can persist in seminal fluid of male survivors for many months, posing a risk of sexual transmission.

Diagnosis

Clinically distinguishing it from other infectious diseases like malaria, typhoid fever, or meningitis is difficult. Definitive diagnosis is made using laboratory tests. Methods include detecting viral RNA by reverse transcription polymerase chain reaction, identifying viral proteins by antigen-capture ELISA, or detecting IgM and IgG antibodies. Testing must be conducted under maximum biosafety conditions due to the extreme hazard. The Centers for Disease Control and Prevention and the World Health Organization provide detailed testing protocols and support to outbreak regions.

Prevention

Prevention focuses on infection control measures and community engagement. In healthcare settings, strict use of personal protective equipment and sterilization procedures are critical. Community measures include safe and dignified burial practices, contact tracing, and social distancing. The rVSV-ZEBOV vaccine, marketed as Ervebo, has proven highly effective and was prequalified by the World Health Organization in 2019. Ring vaccination strategy, pioneered during the 2014–2016 West Africa outbreak, is a key tool. Public health messaging by organizations like the International Federation of Red Cross and Red Crescent Societies is vital for compliance.

Treatment

There is no universally proven cure. Management is primarily supportive care, which includes aggressive oral or intravenous fluid resuscitation, maintenance of oxygen status and blood pressure, and treatment of specific complications such as bacterial superinfection. Two monoclonal antibody therapies, Inmazeb (a cocktail of atoltivimab, maftivimab, and odesivimab-ebgn) and Ebanga (ansuvimab-zykl), have been approved by the U.S. Food and Drug Administration after showing efficacy in clinical trials. The antiviral drug remdesivir has shown some benefit in certain settings. Blood transfusions from Ebola survivors have been used historically.

Prognosis

The prognosis is often poor, with an average case fatality rate of around 50%, though it has varied from 25% to 90% in past outbreaks depending on the viral species and the capacity of the healthcare response. Factors associated with a higher risk of death include high viral load, older age, and the development of severe hemorrhagic or neurological symptoms. Survivors may experience long-term sequelae, known as post-Ebola syndrome, which can include chronic fatigue, musculoskeletal pain, eye inflammation, and hearing loss.

Epidemiology

Since its identification, outbreaks have occurred primarily in remote villages in Central and West Africa, near tropical rainforests. Major outbreaks include the 1976 outbreaks in Sudan and Zaire, the 1995 outbreak in Kikwit, the 2000 outbreak in Uganda, and the unprecedented 2014–2016 epidemic primarily affecting Guinea, Sierra Leone, and Liberia, which resulted in over 11,000 deaths. A later, complex outbreak occurred in the Kivu region of the Democratic Republic of the Congo from 2018 to 2020, complicated by conflict and vaccine hesitancy. The World Health Organization occasionally declares such outbreaks a Public Health Emergency of International Concern.

Category:Viral hemorrhagic fevers Category:Infectious diseases Category:Epidemics