Pathophysiology
1) type of hemorrhagic fever caused by infection with Ebola virus 2) three known subtypes (Zaire, Sudan, and Cote d’Ivoire) cause significant disease in humans and one known subtype (Reston) causes subclinical disease in humans
Signs and Symptoms
1) abrupt onset of – fever, malaise, abdominal pain, nausea and vomiting, headache, and myalgia 2) followed by – severe diarrhea, cough, chest pain, decreased mental status, shock, maculopapular rash, desquamation, bleeding from all mucosal surfaces and into skin, pharyngitis, hepatomegaly and jaundice, flushing, and neck, face, and scrotal edema 3) after 10 days – patient either begins to recover or dies
Characteristic Test Findings
Laboratory – 1) greatly increased cytokines 2) increased alpha-interferon 3) leukopenia 4) decreased platelets 5) DIC 6) increased AST and ALT 7) increased amylase 8) diagnosis is by antigen-detection ELISA
Associated Conditions
1) hepatitis 2) uveitis 3) orchitis
Histology/Gross Pathology
1) Ebola is a member of the Filoviridae family 2) single-stranded linear RNA within a helical nucleocapsid and surface marked by glycoproteins 3) virus found in all cell types, with replication causing cell necrosis (e.g., liver necrosis with Councilman’s bodies)
Inheritance/Epidemiology
1) exists in room-temperature blood for weeks 2) Zaire subtype has a 90% mortality; Sudan subtype has a 50% mortality; Cote d’Ivoire has an undetermined mortality 3) very easily transmitted human to human; health-care workers taking care of these patients are at considerable risk (touching a dead body with ungloved hand will transmit the disease) 4) incubation period is 7-10 days 5) can be transmitted sexually 6) animal reservoir likely exists but has not been identified
Treatment
1) no effective antiviral medication exists once a patient has been infected 2) virus can be killed outside of the body by heating to 60 degrees C for 30 minutes or by inducing an acidic environment
Tips for USMLE
1) hemorrhage and fever are the classic findings (but not all cases have bleeding – including many fatal cases) 2) the other Filovirus (hemorrhagic fever virus) is Marburg virus 3) if a missionary doctor returns to the USA from Zaire and 3 days later has rapid onset of fever, headache, nausea, and vomiting that deteriorates 5 days later to striking neck edema, shock, and bleeding from his oral mucosa, think Ebola virus
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