1. IDENTIFICATION

EBOLA-MARBURG VIRAL DISEASES (African hemorrhagic fever, Marburg virus disease, Ebola virus hemorrhagic fever)

Severe acute viral illnesses, usually with sudden onset of fever, malaise, myalgia and headache, followed by pharyngitis, vomiting, diarrhea and maculopapular rash. The accompanying hemorrhagic diathesis is often accompanied by hepatic damage, renal failure, CNS involvement and terminal shock with multiorgan dysfunction. Laboratory findings usually show lymphopenia, severe thrombocytopenia and transaminase elevation (AST greater than ALT), sometimes with hyperamylasemia. Approximately 25% of reported primary cases of Marburg virus infection have been fatal; case-fatality rates of Ebola infections in Africa have ranged from 50% to nearly 90%.

Diagnosis is made by ELISA for specific IgG antibody (presence of IgM antibody suggests recent infection); by ELISA antigen detection in blood, serum or organ homogenates; by PCR; by detection of the virus antigen in liver cells by use of monoclonal antibody in an IFA test; or by virus isolation in cell culture or guinea pigs. Virus may sometimes be visualized in liver sections by EM. Postmortem diagnosis through immunohistochemical examination of formalin-fixed skin biopsy specimens is also possible. IFA tests for antibodies have often been misleading, particularly in serosurveys for past infection. Laboratory studies represent an extreme biohazard and should be carried out only where protection against infection of the staff and community is available (BSL-4 [Biosafety level 4] containment).