Hantavirus

Diagnosis

Indications for Testing

  • Consider diagnosis in thrombocytopenic patients with febrile illness and applicable rodent exposure

Criteria for Diagnosis

Laboratory Testing

  • Initial testing
    • CBC – in cardiopulmonary phase
      • Peripheral smear demonstrates thrombocytopenia – associated with prolonged tachypnea
      • Myelocytosis – >10% lymphocytes with immunoblastic morphology
    • Liver function tests – commonly elevated
    • PT/PTT – prolonged PTT is most common
  • Serologies using ELISA testing – confirm diagnosis
  • PCR – experimental

Histology

  • Immunohistochemical staining (if available) is sensitive

Imaging Studies

  • Chest x-ray – interstitial infiltrates most common; pulmonary edema evident in more severe cases

Differential Diagnosis

Clinical Background

Hantavirus causes hantavirus pulmonary syndrome (HPS) and was first reported in the Americas. Hemorrhagic fever with renal syndrome (HFRS) was first reported in Asia and Europe in 1993.

Epidemiology

  • Incidence – <50 cases annually in U.S.
  • Sex – M>F
  • Transmission – inhalation of infected aerosols from rodents

Organism

  • Hantavirus is the only member of the Bunyaviridae family not arthropod-transmitted
  • Enveloped virus with tri-segmented, negative-stranded RNA
  • Sin Nombre, Bayou, Black Creek Canal, Muleshoe, Monongahela, and New York strains of hantavirus, as well as their sigmodontinae rodent reservoirs, have been identified as definitive causes of HPS in the U.S. and Central and South America

Clinical Presentation

  • Incubation of 1-2 weeks – fever, myalgia, headache, chills, abdominal pain, nonproductive cough, gastrointestinal symptoms
  • HPS – rapid development of dyspnea and pulmonary edema; diffuse infiltrates on chest x-ray
  • Prolonged tachypnea; tachycardia common
  • If hospitalization does not occur, hypotension and shock may follow, resulting in death within 3-6 days

Treatment

  • Supportive care

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential

Assist in ruling out bacterial infection

   
Hepatic Function Panel 0020416
Method: Quantitative Enzymatic/Quantitative Spectrophotometry

Evaluate for hepatitis

   
Prothrombin Time 0030215
Method: Electromagnetic Mechanical Clot Detection

Initial testing to rule out coagulopathy

   
Partial Thromboplastin Time 0030235
Method: Electromagnetic Mechanical Clot Detection

Initial testing to rule out coagulopathy

   
Hantavirus Antibodies, IgG and IgM with Reflex to Confirmation 2001540
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Use to diagnose HPS or HFRS

If screen is positive, confirmation will be added

False positives occur in cytomegalovirus, influenza and Mycoplasma pneumoniae infection

If test results are equivocal, repeat testing in 10-14 days