Hantavirus Pulmonary Syndrome Workup

Updated: Jan 15, 2019
  • Author: David J Cennimo, MD, FAAP, FACP, FIDSA, AAHIVS; Chief Editor: Michael Stuart Bronze, MD  more...
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Laboratory Studies

Specific diagnosis of Hantavirus pulmonary syndrome (HPS) may be achieved by serological techniques, polymerase chain reaction (PCR), and immunohistochemistry (IHC) studies, as follows:

  • RT-PCR can help detect viral RNA in blood and tissues and is the criterion standard for diagnosis. Diagnostic sensitivities and specificities of 100% and 94%, respectively, have been reported. [9]
  • IHC can help detect viral RNA in formalin-fixed tissues with specific antibodies.
  • Most commonly, HPS is confirmed by Hantavirus immunoglobulin M (IgM)–and immunoglobulin G (IgG)–specific serology results, usually measured by performing an enzyme-linked immunoassay. Approximately one third of patients with HPS have an elevated IgM titer at the time of clinical presentation. Another one third of patients have elevated titers of IgM and IgG to Hantavirus at the time of presentation. The remaining third develop an increase in IgG titers without an increase in the IgM titer during convalescence.

The following are other laboratory results that may aid in diagnosis:

  • Complete blood count (CBC) may show leukocytosis with a left shift, thrombocytopenia, and an elevated hematocrit due to hemoconcentration.
  • Peripheral blood smear may show atypical lymphocytes and/or immunoblasts, which have a high predictive value.
  • Hepatic panel may show mild transaminitis, but with a markedly elevated lactate dehydrogenase levels.
  • Coagulation studies may show mildly elevated activated partial thromboplastin time with a normal fibrinogen level. If the fibrinogen level is decreased, disseminated intravascular coagulation (DIC) should be considered.
  • Basic metabolic panel usually shows a baseline BUN and creatinine and a low bicarbonate level.
  • Urinalysis shows proteinuria in about 50% of cases.
  • Creatine kinase levels are elevated in 50% of cases.
  • Arterial blood gas analysis may reveal hypoxemia related to respiratory failure. Development of lactic acidosis and rapid respiratory deterioration usually portend death within 1-2 days.

The serum albumin level is decreased in almost all patients with Hantavirus pulmonary syndrome (HPS). Although this depression represents an acute-phase reactant that may be observed in many types of infections, the presence of severe hypoalbuminemia in a previously healthy patient with an acute onset of respiratory distress should suggest HPS.

Isolation of Hantavirus in tissue culture is not clinically available because of the technical difficulty of achieving this and because of issues related to biosafety.


Imaging Studies

Chest Radiography

The chest radiograph typically shows a pattern of noncardiac pulmonary edema. Perihilar haziness ("shaggy heart sign") is characteristic of HPS. Almost all patients with HPS have interstitial edema due to pulmonary capillary leak, which manifests radiologically as peribronchial cuffing or Kerley B lines. Pleural effusions are also common.

The chest radiograph typically does not show new cardiomegaly or mediastinal widening.


Other Tests

Patients with HPS often have a normal pulmonary wedge pressure, decreased cardiac index, and elevated systemic vascular resistance. However, these studies are not necessary for the diagnosis.


Histologic Findings

The histologic findings of HPS are nonspecific and correlate with the pathophysiology of the disease. Histology of lung tissue reveals capillaritis, pulmonary capillary leak syndrome, or both. Hemorrhage is typically not observed. In patients with severe and/or prolonged hypotension, the kidneys may develop histological findings suggestive of ATN.