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Ebola and Marburg Hemorrhagic Fevers (Note: Ebola and Marburg hemorrhagic fevers (HFs) are discussed together because of similarities between them. Last update 11/2001.
Primary Distribution: Ebola: The Congo, Sudan, Ivory Coast, Gabon, and most recently, Uganda in East, Central, and West Africa. Marburg: Uganda and Kenya in West Africa (Centers for Disease Control [CDC], 2000; World Health Organization [WHO], 2000).
Agent and Vector: The agents for Ebola and Marburg HFs are virions that are members of the Filoviridae family, which is passed human to human through exposure to body fluids or by other means, including handling equipment touched by infected persons. The virus is also transmitted by handling infected animal (primate) tissue. The animal host is not known. Ebola and Marburg HFs are highly contagious, especially in later stages. The CDC has guidelines for management of patients with suspected viral hemorrhagic fever (Centers for Disease Control [CDC], 1996). Ebola and Marburg HFs are considered by the CDC to be Category A biological warfare (BW) agents (CDC, 2000). See bioterror box below.
Incubation: 3-16 days.
Clinical Findings and Treatment
Signs and Symptoms: Ebola and Marburg HFs are characterized by sudden onset of fever, chills, severe headache, and myalgia. On about the fifth day of illness, a maculopapular rash may appear - most prominently on the trunk (the rash may eventually desquamate). Other manifestations appearing at about the same time include pharyngitis, chest pain, abdominal pain, nausea, vomiting, diarrhea, and hemorrhagic symptoms, e.g., bleeding mucosal membranes . Symptoms may increase in severity and include jaundice, pancreatic inflammation, rapid weight loss, prostration, delirium, shock, hepatic failure, massive hemorrhaging, and multi-organ failure (Chin, 2000; McCormick, 1991).
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Bioterror Considerations Ebola and Marburg HFs are considered by the CDC to be Category A biological warfare agents, thus posing a risk to national security because they "can be easily disseminated or transmitted from person to person; cause high mortality, with potential for major public health impact; might cause public panic and social disruption; and require special action for public health preparedness" (CDC, 2000, p. 5). Ebola and Marburg HFs are stable as aerosols and very readily transmitted human-to-human. Though the use of Ebola and Marburg HFs in BW is speculative, their virulence such that they should not be ignored (Federation of American Scientists, 2000). Treatment is supportive and complex, hence treatment of mass casualties would be difficult. |
Complications: The case fatality rate for Ebola infections in Africa ranges from 50-90% and for Marburg infections, about 25%. Complications of recovery may include orchitis, hepatitis, transverse myelitis, or uveitis. Other body systems may also become inflamed.
Lab Findings: early profound lymphopenia with later rapid shift to neutrophilia, thrombocytopenia, elevated AST and ALT (AST greater than ALT) (Chin, 2000).
Diagnosis: Tests include antigen-capture ELISA, IgM-capture ELISA, polymerase chain reaction, and virus isolation (Chin, 2000).
Differential Diagnosis: In early stages, Ebola or Marburg HFs may resemble influenza, malaria, typhoid fever, arboviral fevers (various forms of encephalitis, dengue fever, and other viral hemorrhagic fevers) (McCormick, 1991).
Treatment: There is no specific treatment for Ebola or Marburg HF. Supportive care includes maintaining fluid and electrolyte balance, oxygenation, blood pressure stabilization, blood and clotting factor replacement. Intravenous ribavirin "appears somewhat efficacious" in the treatment of arenaviral diseases (Cieslak & Eitzen, 2000, p. 28). Reporting requirements and procedures are given in the CDC: Management of patients with suspected viral hemorrhagic fever reference below (CDC, 1996; Chin, 2000).
References
Centers for Disease Control. (1996). Notice to readers update: Management of patients with suspected viral hemorrhagic fever -- United States. Morbidity and Mortality Weekly Report. 44(25), 475-479. Available online: http://www.cdc.gov/epo/mmwr/preview/mmwrhtml/00038033.htm
Centers for Disease Control and Prevention. (2000). Biological and chemical terrorism: Strategic plan for preparedness and response. MMWR: Morbidity and Mortality Weekly Report, 49(RR-4), 1-14.
Centers for Disease Control (Accessed 4/2000). Marburg hemorrhagic fever. Available online: http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/marburg.htm
Chin, J. (Ed.) (2000). Control of communicable diseases manual (17th ed.). Washington, DC: American Public Health Association.
Cieslak, T.J. & Eitzen, E.M. (2000). Bioterrorism: Agents of concern. Journal of Public Health Management Practice. 6(4), 19-29.
Federation of American Scientists. (2000). Biological weapons. Retrieved October 31, 2001, from the World Wide Web: http://www.fas.org/index.html
McCormick, J.B. (1991). Ebola and Marburg virus infections. In G.T. Strickland (Ed.), Hunter's Tropical Medicine (7th ed.) (pp. 244-248). Philadelphia: W.B. Saunders Company.
World Health Organization (2000). Disease outbreak news: Ebola haemorrhagic fever in Uganda. Accessed on the World Wide Web 10/16/2000 at http://www.who.int/disease-outbreak-news/index.html. (Readers are encouraged to use this site for current and complete information on major infectious diseases).