The BK virus, a member of the polyomavirus family, has no major consequences of infected except with those that are immunocomprimised or immunosuppressed. The virus was first isolated in 1971 from the urine sample of a renal transplant patient whose initials were B.K.
Similar in genome sequences to the JCV virus they are most easily identified and differentiated from each other through serological tests using specific antibodies or through PCR based genotyping approach. Most people are asymptomatic although the primary BK infections are respiratory infection and fever. The virus makes its way to the kidneys and urinary tract where it lives for the rest of the life of the individual. It is believed that 80% of the population contains a latent form of the virus.
Those individuals that are immunocompromized have more severe manifestations including renal dysfunction and abnormal urinalysis. The transmission of the virus is unknown although it is known that it spreads from human to human and not from an animal source. It is possible the virus is spread through respiratory fluids or urine. Out of 400 blood donors 82% were reported as positive for BK virus.
The virus is diagnosed by BKV blood & urine testing as well as a biopsy in the kidneys. The main therapy is reduction in immunosuppression. Other therapeutic options include leflunomide, Cidofivir, IVIG, and the fluoroquinolones. Leflunomide is the second treatment option after immunosuppression.
Leflunomide works because of its combined immunosuppressive and antiviral properties. However, each patient is different and therefore there are no dosing guidelines for leflunomide in BKVN.