Residual risk of transfusion-transmitted malaria infection in a malaria endemic sub-Saharan African setting

Abstract

BackgroundIn Cameroon, as in many malaria endemic countries in Africa, blood donors are not routinely screened for Plasmodium infection that potentially could lead to severe malaria in some recipients. This study aimed at defining the prevalence of malaria among blood donors in Cameroon, and determining the risk of transfusion-transmitted malaria (TTM) following a single unit of blood transfusion.MethodsA total of 250 blood donors were recruited at the Douala General Hospital in Cameroon. Blood samples were tested for the presence of Plasmodium by using a rapid diagnostic test (RDT), and by thin and thick blood smear microscopy. A mathematical model was performed to calculate individual risk and to estimate population incidence rates of TTM per year. Different data sources were used in the sensitivity analysis prior to estimation of malaria transfusion risk.ResultsMore than half (96.8%) of all blood donors were men, and the mean age of the donors was 28.5 (SD = 8.9) years. Infected volunteer donors represented 2.80% while infected family-replacement donors comprised 97.20%. The prevalence of P. falciparum infection was 12.0%, and the population mean parasite density was 6,056 (95% CI: 4,542–8,076) parasites/μL. The individual median residual risk of TTM was 5.59 per 10,000 or 2.64 per 1,000 units of blood transfused every year in Douala or Cameroon, respectively.ConclusionsThis study confirms the presence of P. falciparum as one of the most prevalent TTIs in the region. The residual risk of TTM is high among blood recipients, urging to conduct in malaria-endemic areas a cost-benefit analysis of systematically screening blood units for malaria parasites before transfusion versus systematically treating the recipient after transfusion.