Dermatologic Manifestations of Viral Hemorrhagic Fevers Workup

Updated: Jan 06, 2020
  • Author: Amira M Elbendary, MBBCh, MSc; Chief Editor: William D James, MD  more...
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Workup

Laboratory Studies

Although the clinical findings can suggest a hemorrhagic fever, laboratory studies are required to identify disease, to distinguish it from other conditions, and to confirm its etiology.

As a rule, clinical blood and/or urine tests reveal leukopenia (except in Lassa fever, Hantaan viral fever, and some severe cases of CCHF), thrombocytopenia (except in Lassa fever), and proteinuria and/or hematuria (in Argentinian viral hemorrhagic fever, Bolivian viral hemorrhagic fever, and hemorrhagic fever with renal syndrome [HFRS]; common in other viral hemorrhagic fevers). Such tests include the following:

  • Full blood cell count determination

  • Red blood cell and sedimentation rate analysis

  • White blood cell differential count determination

  • Platelet count

  • Tests for parasites, malaria, trypanosomiasis, or relapsing fever

  • Coagulation studies

  • Liver and kidney function tests

  • Bacterial culture and virus isolation from feces and urine samples

  • Electron microscopic examination of blood and urine samples

  • Positive tourniquet test in dengue fever (This test may also be helpful in other viral hemorrhagic fevers.)

The specific diagnosis is based on viral isolation or the demonstration of seroconversion, that is, the presence of specific immunoglobulin M (IgM) antibody or a 4-fold increase in the antibody titer.

Specialized infectious disease containment is required for the safe handling of these viruses. Biochemical tests are available for the rapid detection of viral antigen during viremia or in postmortem specimens. Such tests include the following:

  • Immunofluorescence antibody (IFA) tests can be performed.

  • Reversed (or indirect) passive hemagglutination (RPHA) tests may be helpful.

  • Acute serum samples can be tested by using a polymerase chain reaction (PCR).

  • Enzyme-linked immunosorbent assays (ELISA) can be used to detect specific IgM or immunoglobulin G (IgG) antibodies or viral antigens in acute serum samples from patients with Lassa fever, Argentinian fever, RVF, CCHF, or yellow fever. Lassa- and Hantavirus-specific IgM antibodies are often detectable during acute illness.

  • Tests for viral genetic material are favored in diagnoses of acute arenaviral infections.

  • Virus cultivation and identification techniques require 3-10 days or longer for definitive identification. Viral isolation is a lengthy process, especially in Hantaan, Ebola, Marburg, and Congo-Crimean fevers.

  • Postmortem immunocytochemical analyses can be used to identify the viral phenotype.

  • Reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) can be used for the rapid detection of Marburg virus. [69]

  • Reverse-transcription polymerase chain reaction has high sensitivity and specificity to detect the Ebola virus genome. False-negative results may be present in the first 3 days of illness, and repetition of the test may be required. [70]

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Other Tests

Electron microscopy of the infected tissue may be helpful.

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