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Most human cases of West Nile virus infection are acquired via bites from an infected mosquito. In some cases, infection may also be transmitted by infected blood products or transplanted organs. There have been recent publications suggesting that chemotherapy and immunosuppression may increase a person's risks of developing central nervous system disease if the person is infected with the West Nile virus. Because patients undergoing hematopoietic stem cell transplantation not only are immunocompromised, but also receive multiple blood products, they are at a particularly high risk for acquiring symptomatic disease if exposed to the West Nile Virus. We describe here 2 patients who underwent hematopoietic transplantation at our institution and subsequently developed fatal West Nile virus infections.

Summary:It has been suggested that leukoreduced unscreened blood products can be used as an alternative to components from cytomegalovirus (CMV)-seronegative donors in order to prevent transmission of CMV from transfusions for CMV-seronegative marrow transplant recipients with CMV-seronegative donors, but confirmatory data are lacking. A retrospective chart review was undertaken for patients undergoing allogeneic transplantation over a 4-year period during which blood products were filtered for CMV-seronegative patients with CMV-seronegative donors when CMVseronegative components were not available. Forty-five CMV-seronegative patient-donor pairs were identified. Only one patient developed CMV disease (pneumonia) and no other patients developed an infection. In this group of patients, the rate of CMV infection was 2.7% (95% CI, 0-8%) by life-table analysis. We conclude that filtered unscreened blood products as partial transfusion support for CMV-seronegative marrow transplant recipients were associated with a low incidence of CMV infection, justifying further evaluation of filtered blood products as total transfusion support for this patient population. However, since CMV infections still occur, continued surveillance by periodic culture or other techniques is warranted. Keywords: cytomegalovirus infections; filtered blood components; bone marrow transplantation Meyers et al 1 reported that 28% of cytomegalovirus (CMV)-seronegative marrow transplant recipients with CMV-seronegative donors developed CMV infections, and these were attributed to transmission of virus by leukocytes in blood components used for transfusions. Although use of blood products solely from CMV-seronegative donors was associated with a reduction in CMV infection to approximately 3% in CMV-seronegative transplant patients, 2,3 the availability of such blood products is limited by the high incidence of CMV infection in the general population. Leukoreduction by filtration has emerged as an alternative means for providing unscreened blood compoCorrespondence: Dr B Lichtiger, The

Summary:Leukoreduction of blood components has been considered a safe alternative to screening donors for CMV. The objective of this study is to analyze the effectiveness of bedside leukoreduction in preventing CMV transmission. We retrospectively studied 72 transplant recipients and donors who were CMV-seronegative pairs. All patients were transfused with CMV-unscreened cellular blood products leukoreduced at the bedside using leukoreduction filters. Quality control measures performed monthly in our leukoreduced blood components consistently demonstrated that at least 95% of the units sampled meet the leukoreduction criterion established by the American Association of Blood Banks standards. The CMV status of the recipients and donors was determined before transplantation by the latex agglutination assay. Recipients were observed for at least 100 days after transplantation. CMV cultures of urine, buffy coat, bone marrow, and bronchial washings were done weekly when indicated. CMV antigenemia testing was performed twice weekly: 11 transplant recipients seroconverted after transplantation. One patient was positive for CMV antigenemia 4 months after transplantation, but did not have CMV infection. Two of 61 patients who were not seroconverted were CMV antigenemia positive and did not have CMV infection: leukoreduction of cellular blood products is an efficient method of preventing CMV infection.