Virus

Hantavirus

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Hantavirus, Hantavirus Pulmonary Syndrome, Hanta Virus, Sin Nombre Virus, Black Creek Canal Virus, Bayou Virus, New York Virus, Four Corners Virus, Muerto Canyon Virus

  • Epidemiology
  1. United States cases: 280 cases since 1993 (30/year)
  2. Farm settings and other rural areas
    1. Associated with entering rarely opened buildings
    2. Associated with increased rodent populations
  3. Most common in spring and summer
  4. Ages affected
    1. Mean age affected is middle aged adults
    2. Less commonly affects children
  5. Locations in United States
    1. First identified in 1993 in 4 corners (New Mexico, Arizona, Colorado and Utah)
    2. Now HPS has been identified in 31 states and Canada
    3. Initial cases were identified in southwest U.S.
      1. New Mexico
      2. Arizona
      3. California
  • Pathophysiology
  1. Family Hantaviridae (and the genus Orthohantavirus)
    1. Reclassified as of 2018 (previously classified as Bunyaviridae)
    2. Enveloped, Helical single stranded RNA Viruses
  2. Anti-Message Sense RNA Viruses (Negative Stranded, -ssRNA)
    1. Anti-Message sense RNA (-ssRNA) need to first be transcribed into +ssRNA
    2. RNA dependent RNA Polymerase (RNA replicase, RdRp)
      1. RdRp is an enzyme carried by the -ssRNA virus within its capsid
      2. RdRp transcribes -ssRNA into +ssRNA within the host cell
    3. Translation follows +ssRNA transcription from -ssRNA (by RdRp)
      1. As with mRNA, +ssRNA translated by host ribosomes into Protein
  3. Vectors
    1. Deer mouse (main vector): Sin Nombre Virus
    2. Cotton rat (Southeast U.S.): Black Creek Canal Virus
    3. Rice rat (Southeast U.S.): Bayou Virus
    4. White-footed mouse (Northeast U.S.): New York Virus
  4. Transmission
    1. Inhalation of aerosolized rodent feces or Saliva
    2. No identified cases of person to person transmission
    3. No identified Nosocomial Infections
  • Symptoms and Signs
  • Prodromal Phase
  1. Atypical cases may cause only prodromal phase
  2. Symptoms
    1. Mild febrile illness lasting 3-5 days
    2. Myalgias
    3. Gastrointestinal upset
    4. Headache
    5. Chills
    6. Malaise
  3. Signs
    1. Fever
    2. Tachypnea
    3. Tachycardia
  4. Findings rarely seen in HPS (Negative Predictive Value)
    1. Rash, Conjunctivitis (occur with South American HPS)
    2. Rhinorrhea
    3. Pharyngitis
  • Symptoms and Signs
  • Cardiopulmonary Phase
  1. Symptoms
    1. Progressive Tachypnea
    2. Cough productive of copious secretions
  2. Signs: Acute Pulmonary Edema
    1. Hypoxia
    2. Respiratory Failure within first 24 hours
    3. Cardiogenic Shock in severe cases
      1. Low Cardiac Output
      2. Hypotension
      3. High Peripheral Vascular Resistance
      4. Oliguria
  • Labs
  1. Hypoalbuminemia (later finding)
  2. Lactic Acidosis (later finding)
  3. Liver Function Tests elevated
  4. Renal Function Tests
    1. Acute Renal Failure may occur
  5. Complete Blood Count
    1. Repeat in 8-12 hours if initial CBC normal
    2. Combination of all 4 criteria rare in other viral ID
      1. Thrombocytopenia
      2. Leukocytosis with left-shift
      3. Circulating immunoblasts
      4. Hemoconcentration
  • Diagnosis
  1. Sin Nombre Virus serologic titers
  1. Diffuse Interstitial Edema
  2. Pleural Effusions
  3. Differs from ARDS by involving more central lung
  • Differential Diagnosis
  1. Pneumonia
  2. ARDS
  3. Acute Bacterial Endocarditis
  4. Plague
  5. Tularemia
  6. Histoplasmosis
  7. Coccidioidomycosis
  8. Myocardial Infarction
  9. Goodpasture's Syndrome
  • Management
  1. Intensive cardiopulmonary support
    1. Mechanical Ventilation
    2. Pressors
    3. Invasive hemodynamic monitoring
  2. Initial broad spectrum Antibiotics (for other causes)
    1. Employ while awaiting SNV serologic titers
    2. Covers other causes on differential diagnosis
  3. Ribavirin (Virazole)
    1. See Viral Hemorrhagic Fever for protocol
  4. Experimental measures being investigated
    1. Extracorporeal Membrane Oxygenation (ECMO)
  • Prognosis
  1. Mechanical Ventilation required in 90% of patients
  2. Case fatality rate: 40%
  3. Survivors may have persistent small airway obstruction
  4. Survivors often recover within 1 week of illness
  • Prevention
  1. Eliminate rodent populations in and around buildings
  2. Avoid rodent exposure
  • References
  1. (1996) MMWR Morb Mortal Wkly Rep 1996 45:291-5 [PubMed]
  2. Graziano (2002) Am Fam Physician 66:1015-20 [PubMed]
  3. Vitek (1996) Clin Infect Dis 22:824-6 [PubMed]