Association of BK Viruria with Hemorrhagic Cystitis in Recipients of Bone Marrow Transplants

Fifty-three recipients of bone marrow transplants were monitored prospectively for urinary excretion of human polyomaviruses by enzyme-linked immunosorbent assays of urinary supematants and DNA hybridization assays of urinary cells. Excretion of BK virus was demonstrated in 47 percent of the transplant recipients and was the result of the reactivation of latent virus. Hemorrhagic cystitis of long duration (≤7 days) was associated with BK viruria. The disease occurred four times more frequently in patients who excreted BK virus than in those who did not, and the virus was identified in 55 percent of the urine specimens during episodes of cystitis as compared with 8 to 11 percent of the specimens during cystitisfree periods. BK viruria often preceded or coincided with the onset of the disease. Among 19 patients with BK viruria lasting seven days or longer, hemorrhagic cystitis occurred in 15. Occurrence of the disease was related to the source of marrow. The disease occurred in 50 percent of 38 recipients of allogeneic marrow and in 7 percent of 15 recipients of syngeneic or autologous marrow. Among recipients of allogeneic marrow, the disease was observed in 71 percent of the 21 patients excreting BK virus and in 24 percent of the 17 not excreting the virus. An association of BK virus with hemorrhagic cystitis was demonstrated in 16 of the 18 cases of the disease that were adequately characterized. We conclude that reactivation of BK virus may account for a substantial proportion of late-onset, long-lasting hemorrhagic cystitis in recipients of bone marrow transplants. (N Engl J Med 1986; 315:230–4.), The BK type of human polyomavirus is ubiquitous and infects a large proportion of the population, as indicated by serologic surveys.^1,2 Primary infection occurs in childhood and is sometimes associated with a mild respiratory illness.³ The virus probably persists indefinitely in the kidney after primary infection⁴ and is reactivated and excreted in the urine during periods of immunologic impairment. BK viruria is seldom found in normal persons, but it is frequently demonstrable in recipients of renal allografts or bone marrow transplants and in pregnant women.^{5 6 7 8 9} Few clinical illnesses have been firmly associated with BK virus infection. In recipients of renal.