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Essentials of Diagnosis
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Early stage EVD presents as a nonspecific febrile illness
Later stage EVD typically includes severe gastrointestinal symptoms, followed by neurologic symptoms and hypovolemic shock
Hemorrhagic manifestations occur late in course
Uveitis is prominent ocular finding
Travel and contact history from an Ebola-affected country raise suspicion
Diagnosis is confirmed by detection of virus with a real-time polymerase chain reaction
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General Considerations
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Genus Ebolavirus is a single-stranded RNA virus in the Filoviridae family
Fruit bats are possible reservoirs for Ebolavirus
Zoonotic transmission to humans occurs via contact with the reservoir or an infected primate
Transmission
Occurs from direct contact with infected body fluids
Virus must enter the body via mucous membranes, nonintact skin, sexual intercourse (virus has been detected in semen up to 9 months after recovery from infection), breastfeeding, or needlesticks
Prior to symptoms, Ebola is not transmitted
Even at symptom onset, the risk of transmission is low but increases over time
Ebola has a 2- to 21-day incubation period (average is 8–10 days)
The estimated case fatality rate is 60%
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The first Ebola outbreak occurred in 1976 as a simultaneous epidemic in the Democratic Republic of Congo and South Sudan
The number of EVD cases spread rapidly starting in 2014
At least 10 countries have been affected, especially Guinea, Liberia, and Sierra Leone
Many cases and deaths in these countries occurred among health care workers
Countries with effective viral containment as of 2022 include Sierra Leone and Liberia
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Differential Diagnosis
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Varies with the stage of illness
Early-stage EVD
In later stage EVD
Bacterial, viral, and parasitic illnesses, including cholera
In children, rotavirus infection, which can present with severe gastroenteritis and shock
Encephalitis must be differentiated from the confusion associated with uremia
Hemorrhagic manifestations could be due to leukemia, thrombotic thrombocytopenic purpura, hemolytic-uremic syndrome, or disseminated intravascular coagulation (DIC)
Travel and contact history are crucial when considering the differential diagnosis in areas where Ebola is not endemic