BK polyoma virus is a 40-45 nm DNA virus that was first identified in the urine of an immunosuppressed patient in 1971. BK virus infection often occurs in childhood and is subclinical. The majority of adults have antibodies to the virus. Asymptomatic viruria, ureteral ulceration, and ureteral stenosis have been described with infection in immunosuppressed patients. Renal graft dysfunction and interstitial nephritis have been associated with BK virus. Differentiation between rejection and infection is important. We report a case of a renal transplant patient with BK polyoma virus infection. This case illustrates the variety of methods that can be used for identification of BK polyoma virus.

The patient, a 52 year old female, presented with an asymptomatic rise in serum creatinine (1.4 to 2.1 mg/dl). Her past medical history was significant for a cadaver kidney transplant two years prior for polycystic kidney disease.