Comparative Study of Two Malaria Diagnostic Techniques in the Context of Transfusion Safety in Blood Donors at the Yaoundé University Hospital

Malaria is a disease caused by parasites of the genus Plasmodium. Screening is not systematic in blood banks although malaria is endemic in Africa and mainly in Cameroon. The reference diagnostic test for malaria is the thick smear but its performance is complex. More suitable tests for screening malaria in blood banks have been proposed including rapid diagnostic tests (RDT) and thick smear drop. This study aimed to evaluate the performance of rapid diagnostic tests (RDTs) in comparison with thick smear (TS) using thick smear as the reference test. This comparative, descriptive, prospective cross-sectional study took place from January 6, 2023 to June 29, 2023, a period of 6 months at the Yaoundé University Hospital. The target population consisted of volunteer and family blood donors from this hospital who met the selection criteria set by the blood bank. Two hundred volunteers donors were included in the study. The SD Bioline malaria Ag p. f/pan RDT Kit and the Malaria Ag P. f/pan RDT Kit were used to perform the immunochromatographic tests and microscopy was used to read the thick smear and stained smears. The prevalence of asymptomatic malaria carriage in blood donors was 39.5%. Plasmodium falcifarum was the most prevalent species (97.5%) followed by Plasmodium malariae (2.5%), almost half of the donors had parasitemia greater than 200 parasites/μL. The factor that was significantly associated with parasitemia was the absence of use of long-lasting insecticide-treated net (LLIN). Compared with the thick smear as the reference test, both RDTs had a sensitivity of 49.4% and a specificity of 95.06%. The positive predictive value was 84.8% and the negative predictive value 50.6%. The results of this study show that the prevalence of asymptomatic carriage of plasmodium in voluntary blood donors was high, thus constituting a significant risk of transmission of the parasite to recipients often in poor general condition. The thick smear remains the gold standard for the reference technique in the diagnosis of malaria.