The risk of transfusion‐transmitted infections in sub‐Saharan Africa

BACKGROUND: Blood transfusions carry the risk of transmitting infections. This risk has been studied in detail in high‐income countries but not in sub‐Saharan Africa. This study estimates the risks of acquiring human immunodeficiency virus (HIV), hepatitis B virus (HBV), or hepatitis C virus (HCV) from a single unit of blood in sub‐Saharan Africa. STUDY DESIGN AND METHODS: A mathematical model was constructed to quantify transfusion risks across 45 sub‐Saharan African countries using three components: the risk of a contaminated unit entering the blood supply, the risk that the unit will be given to a susceptible patient, and the risk that receipt of the unit will lead to infection in the recipient. Variables included prevalence of infection in donors, extent of blood testing, test sensitivity, and susceptibility of recipients. Data from the World Health Organization (WHO) African Region and a systematic review of the literature were used to parameterize the model. Uncertainty in the risk estimates was quantified using probabilistic sensitivity analysis. RESULTS: The median overall risks of becoming infected with HIV, HBV, and HCV from a blood transfusion in sub‐Saharan Africa were 1, 4.3, and 2.5 infections per 1000 units, respectively. If annual transfusion requirements projected by the WHO were met, transfusions alone would be responsible for 28,595 HBV infections, 16,625 HCV infections, and 6650 HIV infections every year. Sensitivity analysis suggests that the true risks may be even higher. CONCLUSIONS: This study is the first to systematically quantify the risks of transfusion‐transmitted infections across sub‐Saharan Africa. Although the results are limited by the quality and quantity of available data, these may be the most reliable estimates at this time.     

Direct assessment of cytomegalovirus transfusion‐transmitted risks after universal leukoreduction

BACKGROUND: Cytomegalovirus (CMV) transfusion‐transmitted disease (TTD) remains a clinical concern. Universal leukoreduction has become one of the main strategies for the prevention of CMV‐TTD. Through prospective clinical follow‐up and testing of transfusion recipients (TRs), the risk for CMV‐TTD was studied. STUDY DESIGN AND METHODS: Transfused units were all leukoreduced and not prospectively screened for CMV. For TRs with negative baseline CMV testing results (CMV total antibody and DNA), all follow‐up TR samples were tested for CMV total antibody and DNA, and retained linked donor serum samples were tested for CMV total antibody. In cases when CMV‐TTD was suspected, donor sera were also tested for CMV DNA and selected TR samples were tested for CMV immunoglobulin M antibody. Evaluable transfusion was defined as a transfusion with TR sample(s) collected 14 to 180 days posttransfusion. RESULTS: Forty‐six TRs were negative for CMV at baseline. There were 1316 evaluable cellular blood transfusions to these TRs. Of 1316 evaluable cellular products, 460 (35%) were positive for CMV total antibody tested using linked donor samples. Three cases of probable CMV‐TTD were found; however, there was no definitive proof from donor follow‐up that they were transfusion associated. CONCLUSION: Among all 46 baseline seronegative recipients and 1316 evaluable transfusions, the calculated overall CMV‐TTD risk was up to 6.5% (95% confidence interval [CI], 1.0%‐18.0%) in terms of TRs and up to 0.23% (95% CI, 0.06%‐0.62%) in terms of non–CMV‐screened leukoreduced cellular products. In summary, after universal leukoreduction, CMV‐TTD, while uncommon, may still occur.     

TRANSFUSION COMPLICATIONS: A fatal case of transfusion‐transmitted babesiosis in the State of Delaware

BACKGROUND: Most cases of human babesiosis in North America are caused by Babesia microti, which is endemic in the northeastern and upper midwestern United States. Although the disease is usually transmitted by a tick bite, there has been an increase in the number of transfusion‐transmitted cases reported. We describe a fatal case of transfusion‐transmitted babesiosis in a nonendemic state, Delaware. CASE REPORT: The patient was a 43‐year‐old Caucasian woman with history of transfusion‐dependent Diamond‐Blackfan syndrome, hepatitis C, and splenectomy. She was admitted initially for presumptive pneumonia. The next day, a routine examination of the peripheral blood smears revealed numerous intraerythrocytic ring forms, consistent with Babesia. The parasitemia was approximately 5% to 6%. The diagnosis was confirmed by positive polymerase chain reaction (PCR) for B. microti DNA and high titer of antibody to B. microti (1:2048). Despite aggressive therapy including clindamycin and quinine antibiotics, the patient expired 3 days after admission. Subsequently, 13 blood donors were tested for B. microti. All tested donors were negative by PCR. However, one donor living in New Jersey had a significant elevated B. microti antibody titer (1:1024). CONCLUSIONS: We believe that this is the first reported case of transfusion‐transmitted babesiosis in Delaware, a nonendemic state. Our case illustrates that clinicians should consider babesiosis in the differential diagnosis of immunocompromised patients who have fever and recent transfusion history, even in areas where babesiosis is not endemic. It also demonstrates the need for better preventive strategies including more sensitive, specific, and rapid blood donor screening tests to prevent transfusion‐transmitted babesiosis.