Influenza vaccination reveals sex dimorphic imprints of prior mild COVID-19.

Acute viral infections can have durable functional impacts on the immune system long after recovery, but how they affect homeostatic immune states and responses to future perturbations remain poorly understood1-4. Here we use systems immunology approaches, including longitudinal multimodal single-cell analysis (surface proteins, transcriptome and V(D)J sequences) to comparatively assess baseline immune statuses and responses to influenza vaccination in 33 healthy individuals after recovery from mild, non-hospitalized COVID-19 (mean, 151 days after diagnosis) and 40 age- and sex-matched control individuals who had never had COVID-19. At the baseline and independent of time after COVID-19, recoverees had elevated T cell activation signatures and lower expression of innate immune genes including Toll-like receptors in monocytes. Male individuals who had recovered from COVID-19 had coordinately higher innate, influenza-specific plasmablast, and antibody responses after vaccination compared with healthy male individuals and female individuals who had recovered from COVID-19, in part because male recoverees had monocytes with higher IL-15 responses early after vaccination coupled with elevated prevaccination frequencies of 'virtual memory'-like CD8+ T cells poised to produce more IFNγ after IL-15 stimulation. Moreover, the expression of the repressed innate immune genes in monocytes increased by day 1 to day 28 after vaccination in recoverees, therefore moving towards the prevaccination baseline of the healthy control individuals. By contrast, these genes decreased on day 1 and returned to the baseline by day 28 in the control individuals. Our study reveals sex-dimorphic effects of previous mild COVID-19 and suggests that viral infections in humans can establish new immunological set-points that affect future immune responses in an antigen-agnostic manner.

The global blood donation index: an imperfect measure of transfusion need.

The optimum number of units of blood and the associated number of blood donors required to meet a given population's needs remain undetermined globally. Typically, a whole blood donation rate of ten donations per 1000 population, at a minimum, is necessary to meet a country's blood needs. This rate is attributed to a WHO recommendation that 1% of a given country's population should donate blood to ensure a blood supply that is sufficient to meet clinical needs. This often cited metric was first referenced in a 1971 WHO report, yet neither supporting data or references were provided, suggesting that it was flawed at its founding. Regardless, this metric does not provide an accurate or contemporary determination of blood needs, which has ramifications for health service provision and planning, particularly in low-income and lower-middle-income countries. Modelling studies that account for geographical variability in disease burden, health-care infrastructure, and transfusion practices are needed to accurately estimate blood needs. A paucity of data to inform modelling remains a major obstacle in this regard. We discuss the history of the global blood donation index and highlight some factors that should be considered to better understand contemporary blood needs.

Early Outpatient Treatment for Covid-19 with Convalescent Plasma.

BACKGROUND: Polyclonal convalescent plasma may be obtained from donors who have recovered from coronavirus disease 2019 (Covid-19). The efficacy of this plasma in preventing serious complications in outpatients with recent-onset Covid-19 is uncertain. METHODS: In this multicenter, double-blind, randomized, controlled trial, we evaluated the efficacy and safety of Covid-19 convalescent plasma, as compared with control plasma, in symptomatic adults (≥18 years of age) who had tested positive for severe acute respiratory syndrome coronavirus 2, regardless of their risk factors for disease progression or vaccination status. Participants were enrolled within 8 days after symptom onset and received a transfusion within 1 day after randomization. The primary outcome was Covid-19-related hospitalization within 28 days after transfusion. RESULTS: Participants were enrolled from June 3, 2020, through October 1, 2021. A total of 1225 participants underwent randomization, and 1181 received a transfusion. In the prespecified modified intention-to-treat analysis that included only participants who received a transfusion, the primary outcome occurred in 17 of 592 participants (2.9%) who received convalescent plasma and 37 of 589 participants (6.3%) who received control plasma (absolute risk reduction, 3.4 percentage points; 95% confidence interval, 1.0 to 5.8; P = 0.005), which corresponded to a relative risk reduction of 54%. Evidence of efficacy in vaccinated participants cannot be inferred from these data because 53 of the 54 participants with Covid-19 who were hospitalized were unvaccinated and 1 participant was partially vaccinated. A total of 16 grade 3 or 4 adverse events (7 in the convalescent-plasma group and 9 in the control-plasma group) occurred in participants who were not hospitalized. CONCLUSIONS: In participants with Covid-19, most of whom were unvaccinated, the administration of convalescent plasma within 9 days after the onset of symptoms reduced the risk of disease progression leading to hospitalization. (Funded by the Department of Defense and others; CSSC-004 ClinicalTrials.gov number, NCT04373460.).

Blood Banking Capacity in Low-and Middle-Income Countries: Covid-19 Convalescent Plasma in Context.

Blood transfusion capacity in low- and middle-income countries (LMICs), encompassing both the safety and adequacy of the blood supply, is limited. The challenges facing blood banks in LMICs include regulatory oversight, blood donor selection, collection procedures, laboratory testing, and post-transfusion surveillance. A high proportion of LMICs are unable to fully meet clinical demands for blood products, and many do not meet even the minimum threshold of collection (10 units per 1000 population). Suboptimal clinical transfusion practices, in large part due to a lack of training in transfusion medicine, contribute to blood wastage. During the COVID-19 pandemic, high- and LMICs alike experienced blood shortages, in large part due to quarantine and containment measures that impeded donor mobility. COVID-19 convalescent plasma (CCP) was particularly appealing for the treatment of patients with COVID-19 in LMICs, as it is a relatively inexpensive intervention and makes use of the existing blood collection infrastructure. Nonetheless, the challenges of using CCP in LMICs need to be contextualized among broad concerns surrounding blood safety and availability. Specifically, reliance on first time, family replacement and paid donors, coupled with deficient infectious disease testing and quality oversight, increase the risk of transfusion transmitted infections from CCP in LMICs. Furthermore, many LMICs are unable to meet general transfusion needs; therefore, CCP collection also risked exacerbation of pervasive blood shortages.

Thrombosis risk with haemoglobin C trait and haemoglobin C disease: A systematic review.

The thrombotic risk with haemoglobin C trait (HbAC) or haemoglobin C disease (HbCC) is unclear. However, individuals with HbCC have demonstrated chronic haemolysis, higher blood viscosity and altered rheology when compared to individuals with wild-type haemoglobin (HbAA). These physiological alterations may theoretically translate to increased risk of thrombosis; therefore, a systematic literature review was performed to investigate the possible association between HbAC and/or HbCC and thrombosis. Twenty-two studies met inclusion criteria representing 782 individuals with HbAC (n = 694) or HbCC (n = 88). Fifteen studies described the presence/absence of venous thromboembolism (VTE) in patients with HbAC (n = 685) or HbCC (n = 79), while seven studies described patients with HbAC (n = 9) or HbCC (n = 9) and arterial thrombosis. Most (n = 20) studies were case reports or case series; however, two studies suggested a potential increased VTE risk with HbAC compared to HbAA in (i) all patients (OR 2.2, 95% CI: 0.9-5.5) and in (ii) pregnant individuals (RR 3.7, 95% CI 0.9-16). This review is the largest assessment of patients with HbC trait or disease and thrombosis to date; despite its limitations, the findings suggest HbC may be a predisposing risk factor to thrombosis. Prospective cohort studies are warranted to definitively elucidate the risk of thrombosis in this population.

Euvolemic automated transfusion to treat severe anemia in sickle cell disease patients at risk of circulatory overload.

BACKGROUND: Red blood cell (RBC) transfusion remains a major treatment for sickle cell disease (SCD). Patients with SCD have a high prevalence of renal impairment and cardiorespiratory disease, conferring risk of transfusion-associated circulatory overload (TACO). STUDY DESIGN AND METHODS: We describe an approach, titled euvolemic automated transfusion (EAT), to transfuse SCD patients with severe anemia who are at risk of TACO. In EAT, plasmapheresis is performed using donor RBCs, rather than albumin or plasma, as replacement fluid. Euvolemia is maintained. A retrospective analysis was conducted of patients with SCD who underwent EAT at our institution over a 10-year period, to evaluate the efficacy and safety of EAT. RESULTS: Eleven SCD patients underwent 109 EAT procedures (1-59 procedures per patient). The median age was 42 years (IQR = [30-49]) and 82% (n = 9) were female. Most (82%; n = 9) patients had severe chronic kidney disease and 55% (n = 6) had heart failure. One (9%) patient had a history of life-threatening TACO. Mean pre- and post-procedure Hct values were 19.8% (SD ± 1.6%) and 29.1% (SD ± 1.4%), respectively. The average Hct increment was 3.2% per RBC unit. Only two EAT-related complications were recorded during the 109 procedures: central line-associated infection and citrate toxicity (muscle cramping). EAT used an average of two RBC units less than that projected for standard automated RBC exchange. CONCLUSION: Our findings suggest that EAT is safe and effective to treat patients with SCD and severe anemia, who are at risk for TACO. EAT requires fewer RBC units compared to automated RBC exchange.

Chronic automated red cell exchange therapy for sickle cell disease.

BACKGROUND: The data to support chronic automated red cell exchange (RCE) in sickle cell disease (SCD) outside of stroke prevention, is limited, especially in adults. STUDY DESIGN AND METHODS: A retrospective analysis was conducted of patients with SCD who were referred for chronic RCE at our institution over a 10-year period. Data that were evaluated included patient demographics, referral indications, and procedural details (e.g., vascular access, adverse events, etc.). In a subanalysis, the number of annual acute care encounters during 3 years of chronic RCE was compared with that in the year preceding the first RCE. RESULTS: A total of 164 patients were referred for chronic RCE: median age was 28 years (interquartile range [IQR] = 22-36) at referral and 60% were female. Seventy (42.6%) were naïve to chronic transfusion (simple or RCE) prior to referral. The leading indications for referral were refractory pain (73/164, 44.5%) and iron overload (57/164, 34.7%). A total of 5090 procedures occurred during the study period (median = 19, IQR = 5-45). Of the 138 patients who had central vascular access, 8 (6%) and 16 (12%) had ≥1 central-line-related thrombosis and/or infection, respectively. Of those who were not RBC alloimmunized at initiation of RCE, 12/105 (11.4%) developed new antibodies during chronic RCE. In those 30 patients who were adherent to therapy for 3 years, there was no significant difference in acute care encounters following initiation of RCE. CONCLUSION: Prospective clinical trials are needed to determine which patients are most likely to benefit from chronic RCE and refine selection accordingly.

Reevaluation of the medical necessity of washed red blood cell transfusion in chronically transfused adults.

BACKGROUND: Washing red blood cell (RBC) units mitigates severe allergic transfusion reactions. However, washing reduces the time to expiration and the effective dose. Automated washing is time- and labor-intensive. A shortage of cell processor tubing sets prompted review of medical necessity for washed RBC for patients previously thought to require washing. STUDY DESIGN AND METHODS: A single-center, retrospective study investigated discontinuing wash RBC protocols in chronically transfused adults. In select patients with prior requirements for washing, due to a history of allergic transfusion reactions, trials of unwashed transfusions were performed. Patient demographic, clinical, laboratory, and transfusion data were compiled. The per-unit washing cost was the sum of the tubing set, saline, and technical labor costs. RESULTS: Fifteen patients (median age 34 years interquartile range [IQR] 23-53 years, 46.7% female) were evaluated. These patients had been transfused with a median of 531 washed RBC units (IQR 244-1066) per patient over 12 years (IQR 5-18 years), most commonly for recurrent, non-severe allergic reactions. There were no transfusion reactions with unwashed RBCs aside from one patient with one episode of pruritus and another with recurrent pruritus, which was typical even with washed RBC. We decreased the mean number of washed RBC units per month by 72.9% (104 ± 10 vs. 28.2 ± 25.2; p < .0001) and saved US $100.25 per RBC unit. CONCLUSION: Washing of RBCs may be safely reconsidered in chronically transfused patients without a history of anaphylaxis. Washing should be implemented judiciously due to potential lack of necessity and logistical/operational challenges.

Characterization of blood bank and transfusion medicine practices for pregnant individuals with fetuses at risk of hemolytic disease in the United States.

BACKGROUND: Hemolytic disease of the fetus and newborn (HDFN) is caused by maternal alloantibody-mediated destruction of fetal/neonatal red blood cells (RBCs). While the pathophysiology has been well-characterized, the clinical and laboratory monitoring practices are inconsistent. METHODS: We surveyed 103 US institutions to characterize laboratory testing practices for individuals with fetuses at risk of HDFN. Questions included antibody testing and titration methodologies, the use of critical titers, paternal and cell-free fetal DNA testing, and result reporting and documentation practices. RESULTS: The response rate was 44% (45/103). Most respondents (96%, 43/45) assess maternal antibody titers, primarily using conventional tube-based methods only (79%, 34/43). Among respondents, 51% (23/45) rescreen all individuals for antibodies in the third trimester, and 60% (27/45) perform paternal RBC antigen testing. A minority (27%, 12/45) utilize cell-free fetal DNA (cffDNA) testing to predict fetal antigen status. Maternal antibody titers are performed even when the fetus is not considered to be at risk of HDFN based on cffDNA or paternal RBC antigen testing at 23% (10/43) of sites that assess titers. DISCUSSION: There is heterogeneity across US institutions regarding the testing, monitoring, and reporting practices for pregnant individuals with fetuses at risk of HDFN, including the use of antibody titers in screening and monitoring programs, the use of paternal RBC antigen testing and cffDNA, and documentation of fetal antigen results. Standardization of laboratory testing protocols and closer collaboration between the blood bank and transfusion medicine service and the obstetric/maternal-fetal medicine service are needed.

Deferral of blood donors who have ever stayed in a Trypanosoma cruzi endemic area: An international survey.

BACKGROUND AND OBJECTIVES: Trypanosoma cruzi is the etiologic agent of Chagas disease (CD), an anthropozoonosis from the American continent that progresses from an acute phase to an indeterminate phase, followed by a chronic symptomatic phase in around 30% of patients. In countries where T. cruzi is not endemic, many blood transfusion services test blood donors who have stayed in an endemic country ('at-risk stay')-even if they do not present with other risk factors. However, the efficiency of this approach has been questioned. MATERIALS AND METHODS: On 18 September 2023, a worldwide survey was distributed among employees of blood transfusion services. The questions mainly pertained to CD's endemicity in the blood services' region, the current testing policy for T. cruzi and the number of confirmed positive results among donors with a prior at-risk stay alone (i.e., without other risk factors for T. cruzi infection). RESULTS: Twenty-six recipients completed the survey. Of the 22 (84.6%) blood services that operated in a non-endemic region, 9 (42.9%) tested donors for T. cruzi, including 8 (88.9%) that considered the travel history or the duration of the stay (alone) in their testing algorithm ('study blood services'). Over 93 years of observation among all study blood services, 2 donations from donors with an at-risk stay alone and 299 from those with other risk factors were confirmed positive for T. cruzi. CONCLUSION: The study findings question the utility of testing blood donors who have stayed in an endemic country without other risk factors.

Current state and potential applications of neonatal Fc receptor (FcRn) inhibitors in hematologic conditions.

The neonatal fragment crystallizable (Fc) receptor (FcRn) transports IgG across mucosal surfaces and the placenta and protects IgG from degradation. Numerous clinical trials are investigating therapeutic FcRn inhibition for various immune-mediated neuromuscular and rheumatologic conditions; however, FcRn inhibition also represents a potential therapy for IgG-mediated hematologic conditions (e.g., immune thrombocytopenia, autoimmune hemolytic anemia, immune thrombotic thrombocytopenic purpura, acquired hemophilia, red blood cell/platelet alloimmunization). Current evidence derived from both in vitro and in vivo studies suggests that FcRn inhibitors effectively reduce total IgG levels without impacting its production or altering the levels of other immunoglobulin isotypes. Moreover, the risk of serious adverse events, including serious infections, appears to be lower than that seen with other commonly used immunomodulatory/immunosuppressive therapies, albeit in the setting of limited clinical trial data. Ultimately, additional clinical trials that include varied patient populations are required prior to incorporating these agents into standard treatment algorithms for most hematologic conditions. However, based on the pathophysiology of IgG-mediated hematologic disorders and the mechanism of action of FcRn inhibitors, these agents may represent a future novel therapeutic strategy for patients with hematologic conditions caused by IgG antibodies.

New threats from an old foe: Evaluating the risk to the blood supply due to increasing incidence and endemicity of leprosy in the United States.

Leprosy (i.e., Hansen's disease) is a chronic disease secondary to infection with either Mycobacterium leprae or M. lepromatosis. While the incidence of this disease is decreasing across the world, there is mounting evidence that it might be increasing, and becoming endemic, in the United States. Leprosy was once considered a potential threat to the blood supply, and while this threat has not borne out, it is worth revisiting the available data to assess whether it may pose a threat in the future. Herein, we discuss the evidence for and against the potential for transfusion-transmission of leprosy, and highlight future areas of research to further elucidate this possibility.

The use of predictive modelling to determine the likelihood of donor return during the COVID-19 pandemic.

Artificial intelligence (AI) uses sophisticated algorithms to "learn" from large volumes of data. This could be used to optimise recruitment of blood donors through predictive modelling of future blood supply, based on previous donation and transfusion demand. We sought to assess utilisation of predictive modelling and AI blood establishments (BE) and conducted predictive modelling to illustrate its use. A BE survey of data modelling and AI was disseminated to the International Society of Blood transfusion members. Additional anonymzed data were obtained from Italy, Singapore and the United States (US) to build predictive models for each region, using January 2018 through August 2019 data to determine likelihood of donation within a prescribed number of months. Donations were from March 2020 to June 2021. Ninety ISBT members responded to the survey. Predictive modelling was used by 33 (36.7%) respondents and 12 (13.3%) reported AI use. Forty-four (48.9%) indicated their institutions do not utilise predictive modelling nor AI to predict transfusion demand or optimise donor recruitment. In the predictive modelling case study involving three sites, the most important variable for predicting donor return was number of previous donations for Italy and the US, and donation frequency for Singapore. Donation rates declined in each region during COVID-19. Throughout the observation period the predictive model was able to consistently identify those individuals who were most likely to return to donate blood. The majority of BE do not use predictive modelling and AI. The effectiveness of predictive model in determining likelihood of donor return was validated; implementation of this method could prove useful for BE operations.

Suspected autoimmune encephalitis: A retrospective study of patients referred for therapeutic plasma exchange.

INTRODUCTION: Autoimmune encephalitis (AE) comprises a heterogeneous group of autoantibody-mediated disorders targeting the brain parenchyma. Therapeutic plasma exchange (TPE), one of several first-line therapies for AE, is often initiated when AE is suspected, albeit prior to an established diagnosis. We sought to characterize the role of TPE in the treatment of suspected AE. METHODS: A single-center, retrospective analysis was performed of adults (≥18 years) who underwent at least one TPE procedure for "suspected AE." The following parameters were extracted and evaluated descriptively: clinicopathologic characteristics, treatment course, TPE-related adverse events, outcomes (e.g., modified Rankin scale [mRS]), and diagnosis once investigation was complete. RESULTS: A total of 37 patients (median age 56 years, range 28-77 years, 62.2% male) were evaluated. Autoimmune antibody testing was positive in serum for 43.2% (n = 16) and cerebrospinal fluid for 29.7% (n = 11). Patients underwent a median of five TPE procedures (range 3-16), with 97.3% (n = 36) via a central line and 21.6% (n = 8) requiring at least one unit of plasma as replacement fluid. Fifteen patients (40.5%) experienced at least one TPE-related adverse event. Compared with mRS at admission, the mRS at discharge was improved in 21.6% (n = 8), unchanged in 59.5% (n = 22), or worse in 18.9% (n = 7). Final diagnosis of AE was determined to be definite in 48.6% (n = 18), probable in 8.1% (n = 3) and possible in 27.0% (n = 10). Six (16.2%) patients were ultimately determined to have an alternate etiology. CONCLUSION: Empiric TPE for suspected AE is generally well-tolerated. However, its efficacy remains uncertain in the absence of controlled trials, particularly in the setting of seronegative disease.

Symptom Duration and Resolution With Early Outpatient Treatment of Convalescent Plasma for Coronavirus Disease 2019: A Randomized Trial.

BACKGROUND: Coronavirus disease 2019 (COVID-19) convalescent plasma (CCP) reduces hospitalizations among outpatients treated early after symptom onset. It is unknown whether CCP reduces time to symptom resolution among outpatients. METHODS: We evaluated symptom resolution at day 14 by trial arm using an adjusted subdistribution hazard model, with hospitalization as a competing risk. We also assessed the prevalence of symptom clusters at day 14 between treatments. Clusters were defined based on biologic clustering, impact on ability to work, and an algorithm. RESULTS: Among 1070 outpatients followed up after transfusion, 381 of 538 (70.8%) receiving CCP and 381 of 532 (71.6%) receiving control plasma were still symptomatic (P = .78) at day 14. Associations between CCP and symptom resolution by day 14 did not differ significantly from those in controls after adjustment for baseline characteristics (adjusted subdistribution hazard ratio, 0.99; P = .62). The most common cluster consisted of cough, fatigue, shortness of breath, and headache and was found in 308 (57.2%) and 325 (61.1%) of CCP and control plasma recipients, respectively (P = .16). CONCLUSIONS: In this trial of outpatients with early COVID-19, CCP was not associated with faster resolution of symptoms compared with control. Overall, there were no differences by treatment in the prevalence of each symptom or symptom clusters at day 14. CLINICAL TRIALS REGISTRATION: NCT04373460.

Coronavirus Disease 2019 Convalescent Plasma Utilization in the United States: Data From the National Inpatient Sample.

Coronavirus disease 2019 (COVID-19) convalescent plasma (CCP) use between October and December 2020 was characterized using the National Inpatient Sample database. CCP was administered in 18.0% of COVID-19-associated hospitalizations and was strongly associated with older age and increased disease severity. There were disparities in the receipt of CCP by race and ethnicity, geography, and insurance.

Guidance on the Use of Convalescent Plasma to Treat Immunocompromised Patients With Coronavirus Disease 2019.

Coronavirus disease 2019 (COVID-19) convalescent plasma (CCP) is a safe and effective treatment for COVID-19 in immunocompromised (IC) patients. IC patients have a higher risk of persistent infection, severe disease, and death from COVID-19. Despite the continued clinical use of CCP to treat IC patients, the optimal dose, frequency/schedule, and duration of CCP treatment has yet to be determined, and related best practices guidelines are lacking. A group of individuals with expertise spanning infectious diseases, virology and transfusion medicine was assembled to render an expert opinion statement pertaining to the use of CCP for IC patients. For optimal effect, CCP should be recently and locally collected to match circulating variant. CCP should be considered for the treatment of IC patients with acute and protracted COVID-19; dosage depends on clinical setting (acute vs protracted COVID-19). CCP containing high-titer severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies, retains activity against circulating SARS-CoV-2 variants, which have otherwise rendered monoclonal antibodies ineffective.

Transfusing Convalescent Plasma as Post-Exposure Prophylaxis Against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection: A Double-Blinded, Phase 2 Randomized, Controlled Trial.

BACKGROUND: The efficacy of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) convalescent plasma (CCP) for preventing infection in exposed, uninfected individuals is unknown. CCP might prevent infection when administered before symptoms or laboratory evidence of infection. METHODS: This double-blinded, phase 2 randomized, controlled trial (RCT) compared the efficacy and safety of prophylactic high titer (≥1:320 by Euroimmun ELISA) CCP with standard plasma. Asymptomatic participants aged ≥18 years with close contact exposure to a person with confirmed coronavirus disease 2019 (COVID-19) in the previous 120 hours and negative SARS-CoV-2 test within 24 hours before transfusion were eligible. The primary outcome was new SARS-CoV-2 infection. RESULTS: In total, 180 participants were enrolled; 87 were assigned to CCP and 93 to control plasma, and 170 transfused at 19 sites across the United States from June 2020 to March 2021. Two were excluded for screening SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) positivity. Of the remaining 168 participants, 12/81 (14.8%) CCP and 13/87 (14.9%) control recipients developed SARS-CoV-2 infection; 6 (7.4%) CCP and 7 (8%) control recipients developed COVID-19 (infection with symptoms). There were no COVID-19-related hospitalizations in CCP and 2 in control recipients. Efficacy by restricted mean infection free time (RMIFT) by 28 days for all SARS-CoV-2 infections (25.3 vs 25.2 days; P = .49) and COVID-19 (26.3 vs 25.9 days; P = .35) was similar for both groups. CONCLUSIONS: Administration of high-titer CCP as post-exposure prophylaxis, although appearing safe, did not prevent SARS-CoV-2 infection. CLINICAL TRIALS REGISTRATION: NCT04323800.

Transfusion-transmitted Babesia spp.: a changing landscape of epidemiology, regulation, and risk mitigation.

Babesia spp. are tick-borne parasites with a global distribution and diversity of vertebrate hosts. Over the next several decades, climate change is expected to impact humans, vectors, and vertebrate hosts and change the epidemiology of Babesia. Although humans are dead-end hosts for tick-transmitted Babesia, human-to-human transmission of Babesia spp. from transfusion of red blood cells and whole blood-derived platelet concentrates has been reported. In most patients, transfusion-transmitted Babesia (TTB) results in a moderate-to-severe illness. Currently, in North America, most cases of TTB have been described in the United States. TTB cases outside North America are rare, but case numbers may change over time with increased recognition of babesiosis and as the epidemiology of Babesia is impacted by climate change. Therefore, TTB is a concern of microbiologists working in blood operator settings, as well as in clinical settings where transfusion occurs. Microbiologists play an important role in deploying blood donor screening assays in Babesia endemic regions, identifying changing risks for Babesia in non-endemic areas, investigating recipients of blood products for TTB, and drafting TTB policies and guidelines. In this review, we provide an overview of the clinical presentation and epidemiology of TTB. We identify approaches and technologies to reduce the risk of collecting blood products from Babesia-infected donors and describe how investigations of TTB are undertaken. We also describe how microbiologists in Babesia non-endemic regions can assess for changing risks of TTB and decide when to focus on laboratory-test-based approaches or pathogen reduction to reduce TTB risk.

Therapeutic Plasma Exchange: Core Curriculum 2023.

From producing individual blood components for transfusion to the removal of pathogenic substances, apheresis is a cornerstone of modern medical therapies. The use of therapeutic plasma exchange (TPE), in which plasma and its soluble constituents are removed from the body in exchange for a replacement fluid, can be organ- and life-saving in many diseases. Given the notable similarities between TPE and hemodialysis, the nephrologist is often responsible for managing TPE. As such, one must be familiar with the technologies, approach to therapy, indications for use, and complications. TPE uses centrifugation or membrane separation technologies, with the latter able to be performed with certain hemodialysis machines familiar to the nephrologist. Furthermore, primary kidney diseases such as anti-glomerular basement membrane disease are frequently associated with autoantibodies, potentially making them ideal candidates for TPE. Nevertheless, the use of TPE in many kidney diseases is controversial because of the lack of supporting evidence. This review discusses TPE from the perspective of a nephrologist responsible for prescribing and managing TPE, as well as nephrologists engaged in the care of patients undergoing the procedure.