Abstract
BACKGROUND: Transfusion-transmitted malaria remains a significant challenge in endemic areas and is a leading cause of blood donation deferral. Rigorous clinical and molecular screening is essential to ensure the safety of blood components. The presence of low-density Plasmodium spp. parasitemia in asymptomatic individuals can compromise transfusion safety and perpetuate disease transmission. This study aimed to describe malaria positivity detected by the NAT PLUS HIV/HBV/HCV/Malaria kit (Bio-Manguinhos), as well as to characterize the epidemiological profile of blood donors and the main deferral causes at a reference blood center in the Brazilian Amazon. MATERIALS AND METHODS: This was a retrospective observational study using secondary data from the HemoSys database, which included sociodemographic variables, clinical screening, and self-reported malaria history from blood donors. Cases of clinical malaria were investigated among NAT PLUS-positive donors within six months before and after the reactive donation. RESULTS: A total of 67,114 blood donors tested using the NAT PLUS assay were included. The median age was 35 years (IQR 25-43), with a predominance of male donors (65.1%). Most self-identified as mixed race (80.5%) and had completed high school (53.3%). Malaria-related factors accounted for 2.6% of deferrals (No.=27,434). Malaria positivity detected by NAT PLUS assay was 0.01% (8/67,114), with all reactive donors being asymptomatic at screening. Most positive cases (6/8) occurred during the low-transmission period (rainy season). One donor (12.5%) developed symptomatic malaria (P. falciparum), confirmed by thick blood smear and notified in the SIVEP-Malaria system shortly after donation. DISCUSSION: Individuals testing positive for Plasmodium spp. by NAT PLUS assay may progress to clinical malaria post-donation, posing risks to both donor health and transfusion safety. The frequent absence of information on malaria exposure during clinical screening highlights the need for standardized protocols and molecular testing to improve early identification of at-risk donors in endemic regions.