Search

Background: Babesiosis is an emerging infectious disease caused by intraerythrocytic Babesia parasites that can cause severe disease and death. While blood type is known to affect the mortality of Plasmodium falciparum malaria patients, associations between red blood cell (RBC) antigens and Babesia microti infection and disease severity are lacking. Methods: We evaluated RhD and ABO blood types of Babesia-infected (18S rRNA reactive) blood donors in 10 endemic states in the Northeastern and northern Midwestern United States. We also assessed possible associations between RhD and ABO blood types and disease severity among hospitalized babesiosis patients in Connecticut. Results: A total of 768 Babesia-infected blood donors were analyzed, of which 750 (97.7%) had detectable B. microti-specific antibodies. B. microti-infected blood donors were more likely to be RhD- (OR of 1.22, p-value 0.024) than RhD+ donors. Hospitalized RhD- babesiosis patients were more likely than RhD+ patients to have high peak parasitemia (p-value 0.017), which is a marker for disease severity. No differences in RhD+ blood type were noted between residents of the Northeast (OR of 0.82, p-value 0.033) and the Midwest (OR of 0.74, p-value 0.23). Overall, ABO blood type was not associated with blood donor B. microti infection, however, B. microti-infected donors in Maine and New Jersey were more likely to be blood type B compared to non-type B (OR 2.49 [p = 0.008] and 2.07 [p = 0.009], respectively), while infected donors from Pennsylvania were less likely to be type B compared to non-type B (OR 0.32 [p = 0.02]). Conclusions: People expressing RhD antigen may have a decreased risk of B. microti infection and babesiosis severity. The association of B antigen with B. microti infection is less clear because the antigen appeared to be less prevalent in infected Pennsylvania blood donors but more prevalent in Maine and New Jersey infected donors. Future studies should quantify associations between B. microti genotypes, RBC antigens, and the frequency and severity of B. microti infection to increase our understanding of human Babesia pathogenesis and improve antibody, vaccine, and RBC exchange transfusion strategies. Author summary: We found an association between Babesia microti infection and both red blood cell RhD and B antigens. Numerous studies have quantified the impact of ABO blood type on Plasmodium falciparum (Pf) infection, an intraerythrocytic pathogen in the same Apicomplexa phylum as Babesia. For example, type O blood has been noted to protect against severe malaria, which may explain why type O is prevalent in Pf-endemic regions. Studies of ABO and RhD blood types and B. microti infection are lacking. The American Red Cross has a large blood donor dataset from B. microti-endemic states that can be used to study how ABO and RhD blood types are linked to B. microti infection, as measured by the presence of B. microti 18S rRNA. Data from 10 B. microti-endemic states showed that B. microti-infected blood donors were significantly less likely to be RhD+ (OR 0.82, p-value 0.024) than RhD- donors. A review of babesiosis patients admitted to Yale New Haven Hospital between 2011 and 2021 revealed that RhD+ patients were significantly less likely than RhD- patients to have a high (>5%) peak parasitemia (p = 0.017), which correlates with disease severity. Thus, the RhD antigen on the RBC membrane may decrease the risk of B. microti infection and disease severity. The blood type B antigen may affect the frequency of B. microti infection. The odds ratios (ORs) of B. microti infection in blood donors for blood type B compared to non-type B were 2.49 (p = 0.008) in Maine and 2.07 (p = 0.009) in New Jersey, but 0.32 (p = 0.02) in Pennsylvania. Future studies should quantify the impact of RhD, ABO, and other RBC antigens on Babesia infection, and the mechanisms by which they impact RBC invasion and babesiosis severity. [ABSTRACT FROM AUTHOR]

"Conventional exchange transfusion"—that delivers nondescript "standard issue" units of red blood cells (RBCs)—is used worldwide to rescue dying Plasmodium falciparum (Pf) malaria patients. Recently, exchanging special malaria‐resistant RBCs (T‐REX) has been recommended to prevent random delivery of malaria‐susceptible RBCs that promote Pf infection. Fortunately, Papua New Guinea (PNG) is well positioned to help optimize exchange as "a rescue adjunct" because (a) Gerbich‐negative (GN) RBCs that resist Pf invasion are prevalent in PNG; (b) with international support, PNG has conducted outstanding malaria research; (c) PNG's scientists feel studies of GN RBCs can advance malaria therapeutics; and (d) with blood‐bank support, evaluating exchange of GN RBCs is feasible in PNG. An exchange‐transfusion study of GN RBCs might attract international sponsorship given the threat of expanding drug‐resistance as well as growing recognition that advancing transfusion medicine and expanding blood donation could especially help Pf‐infected children—immediately. [ABSTRACT FROM AUTHOR]

This study had two objectives: (1) to determine if, in the United States of America (US), the proportion of non-US citizen international medical graduates (non-US IMGs) entering pathology residencies had increased (again) in 2019 and (2) to assess how this multi-year trend might impact transfusion medicine in the US. The most recent (2019) "National Resident Matching Program" (NRMP) data were analyzed. To assess potential future impact, using controversies related to Plasmodium falciparum (Pf) malaria, conflicting US and non-US perspectives were reviewed. Differences between published US and non-US views were identified regarding, for example, the value of Pf -resistant ("variant") red blood cells (RBCs) and exchange transfusions. Year 2019 is the first year non-US IMGs were the largest group to fill residency-training positions for a major US specialty via the "Main Residency Match." Also notable, US and non-US views were found to differ markedly regarding (1) the value and safety of Pf -resistant RBC variants and exchange transfusions, and (2) the threat of drug-resistant Pf -malaria parasites. Non-US clinicians and researchers seem more concerned about Pf -malaria, and their interest in cellular therapies seems greater and more optimistic. In 2019, the historically high proportion of non-US IMGs among incoming pathology residents dramatically highlights the steady demographic shift that began years ago: "the internationalization of pathology" in the US. Fortunately, a review of publications related to exchange transfusion, Pf -malaria, and variant RBCs suggests non-US IMGs may markedly promote and advance cell therapies such as therapeutically-rational exchange (T-REX) of disease-resistant RBCs. [ABSTRACT FROM AUTHOR]