BK Virus

BK Virus

 

BK virus is a polyoma virus in the same family of viruses as human papilloma and JC virus.

Epidemiology

  • Prevalence
    • Primary BK infection generally occurs in childhood (without specific symptoms)
      • Most are seropositive by 5 years
  • Transmission
    • The virus is transmitted via respiratory secretions  
  • Organism
    • Double-stranded DNA virus
    • Genetically similar to JC virus

Clinical Presentation

  • Clinical disease is rare in immunocompetent adults
  • BK virus infections are a cause of morbidity and mortality for patients with hematologic malignancies and transplants
  • Illnesses caused by BK virus include:
    • Nephropathy and graft loss in renal transplant patients
      • BK virus allograft nephropathy (BKVAN) is present in up to 8% of kidney transplant patients
        • Tubulointerstitial nephritis is the most common manifestation 
      • New immunosuppressive regimens may increase the risk of BKVAN
    • Hemorrhagic cystitis and renal impairment in patients with hematologic malignancy and bone marrow transplant

Diagnosis

  • Gold standard in BKVAN is renal biopsy
    • Demonstration of BK virus inclusions in renal cells
  • PCR assay
    • More sensitive than urine cytology measurements
    • Provides objective estimate of viral load

Differential Diagnosis

  • Other viral infections
  • Acute or chronic rejection
  • Malignancy

Treatment

  • Bone marrow/hematologic malignancies
    • Supportive in hemorrhagic cystitis; most patients recover
    • Refractory cystitis may be catastrophic
      • Poor response to antiviral therapy
  • Renal transplant
    • If no active rejection present, judicious reduction of immune suppression is acceptable and usually decreases viral load

See Also