Hemorrhagic Fevers Caused by Filoviruses: Ebola and Marburg

CliniCal Manifestations: Data on Ebola and Marburg virus infections primarily are derived from adult populations. More is known about Ebola virus disease than Marburg virus disease, although the same principles apply generally to all filoviruses that cause human disease. Asymptomatic cases of human filovirus infections have been reported, and symptomatic disease ranges from mild to severe disease; case fatality rates for severely affected people range from 25% to 90% (approximately 70% in the 2014 outbreak). After a typical incubation period of 8 to 10 days (range, 2–21 days), disease in children and adults begins with nonspecific signs and symptoms including fever, headache, myalgia, abdominal pain, and weakness followed several days later by vomiting, diarrhea, and unexplainedbleeding or bruising. Respiratory symptoms are more common in children, and central nervous system manifestations are less common in children than in adults. A fleeting maculopapular rash on the torso or face after approximately 4 to 5 days of illness may occur. Conjunctival injection or subconjunctival hemorrhage may be present. Hepatic dysfunction, with elevations in aspartate transaminase (AST) markedly higher than alanine transaminase (ALT), and metabolic derangements, including hypokalemia, hyponatremia, hypocalcemia, and hypomagnesemia, are common. In the most severe cases, microvascular instability ensues around the end of the first week of disease. Although hemostasis is impaired, hemorrhagic manifestations develop in a minority of patients. In the 2001 Uganda Sudan Ebola virus outbreak, all children with laboratory-confirmed Ebola virus disease were febrile, and only 16% had hemorrhage. The most common hemorrhagic manifestations consist of bleeding from the gastrointestinal tract, sometimes with oozing from the mucus membranes or venipuncture sites in the late stages. Central nervous system manifestations and renal failure are frequent in end-stage disease. In fatal cases, death typically occurs around 10 to 12 days after symptom onset, usually resulting from viral-or bacterial-induced septic shock and multi-organ system failure. Approximately 30% of pregnant women with Ebola virus disease present with spontaneous abortion and vaginal bleeding. Maternal mortality approaches 90% when infection occurs during the third trimester. All neonates born to mothers with active Ebola virus disease to date have died. The exact cause of the neonatal deaths is unknown. etiology: The Filoviridae (from the Latin filo meaning thread, referring to their filamen-tous shape) are single-stranded, negative-sense RNA viruses. Four of the 5 species of virus in the Ebolavirus genus and both of the known species of virus in the Marburgvirus genus are associated with human …