Hantavirus

Diagnosis

Indications for Testing

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

Criteria for Diagnosis

• Hantavirus case definition (CDC)

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

• Community-acquired pneumonia
• Sepsis
• Severe acute respiratory syndrome (SARS)
• Acute respiratory distress syndrome/diffuse alveolar damage
• Pulmonary hemorrhage syndromes
  • M. tuberculosis
  • Goodpasture syndrome
• Rickettsia rickettsii (Rocky Mountain spotted fever)
• Francisella tularensis
• Yersinia pestis
• Leptospira spp
• Histoplasma capsulatum
• Coccidioides immitis
• Myocardial infarction with pulmonary edema
• Acute congestive heart failure

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