Inactivation of Plasmodium falciparum in whole blood by riboflavin plus irradiation

Dose-dependent inactivation of Plasmodium falciparum in red blood cell concentrates by treatment with short-wavelength ultraviolet light

BACKGROUND AND OBJECTIVES

Plasmodium species are naturally transmitted by Anopheles mosquitos. The parasite infects red blood cells (RBCs) and can be transfused with blood products. In non-endemic areas, the main risk of infection arises from travellers coming back and people immigrating from malaria-endemic regions. Endemic countries face a permanent risk of infection from transfusion-transmitted malaria (TTM). TTM may cause life-threatening complications in patients dependent on blood donations. This study aimed to investigate the efficacy of Plasmodium falciparum inactivation in RBC units by treatment with short-wavelength ultraviolet C (UVC) light in the absence of photochemical additives.

MATERIALS AND METHODS

RBC units were spiked with P. falciparum to a parasite density of 0.1%-1% and irradiated with up to 4.5 J/cm2 UVC. The parasite density of UVC-treated dilution series and untreated controls were compared over 3 weeks after irradiation.

RESULTS

The lowest dose of 1.5 J/cm2 UVC led to a 3.1 log reduction in parasite load compared with the untreated control. The inactivation capacity was dose-dependent. Strikingly, 4.5 J/cm2 led to ≥5.3 log unit reduction, which was equivalent to a complete inactivation in two out of three experiments.

CONCLUSION

Pathogen reduction with UVC light was previously shown to be effective for different bacteria and viruses, but the inactivation of parasites in RBC concentrates was not addressed until now. The present study provides evidence for significant inactivation of P. falciparum-infected RBCs by UVC light.

Robust inactivation of Plasmodium falciparum in red blood cell concentrates using amustaline and glutathione pathogen reduction

BACKGROUND

Plasmodium falciparum is the parasite responsible for most malaria cases globally. The risk of transfusion-transmitted malaria (TTM) is mitigated by donor deferrals and blood screening strategies, which adversely impact blood availability. Previous studies showed robust inactivation of P. falciparum using nucleic acid-targeting pathogen reduction technologies (PRT) for the treatment of plasma and platelet components or whole blood (WB). The efficacy of the amustaline-glutathione (GSH) PRT to inactivate P. falciparum is here evaluated in red blood cells (RBC), as well the impact of PRT on parasite loads, stages, and strains.

STUDY DESIGN AND METHODS

RBC units resuspended in AS-1 or AS-5 additive solutions were spiked with ring stage-infected RBC and treated with the amustaline-GSH PRT. Parasite loads and viability were measured in samples at the time of contamination, and after treatment, using serial 10-fold dilutions of the samples in RBC cultures maintained for up to 4 weeks.

RESULTS

P. falciparum viability assays allow for the detection of very low levels of parasite. Initial parasite titer was >5.2 log₁₀ /ml in AS-1/5 RBC. No infectious parasites were detected in amustaline-GSH-treated samples after 4 weeks of culture. Amustaline-GSH inactivated high parasite loads regardless of parasite stages and strains. Amustaline readily penetrates the parasite, irreversibly blocks development, and leads to parasite death and expulsion from RBC.

DISCUSSION

Amustaline-GSH PRT demonstrated robust efficacy to inactivate malaria parasites in RBC concentrates. This study completes the portfolio of studies demonstrating the efficacy of nucleic acid-targeting PRTs to mitigate TTM risks as previously reported for platelet concentrates, plasma, and WB.

Pathogen reduction of whole blood: Supplementing fibrinogen partly corrects clot formation in a massive transfusion model

BACKGROUND

The use of whole blood (WB) to treat trauma patients is becoming more common. Similar to the treatment of individual components, pathogen inactivation (PI) technologies are available to treat WB. The impact of PI on WB function is not well understood. This study investigated the impact of PI of WB with riboflavin/ultraviolet (UV) light on its hemostatic function by modeling transfusion scenarios for trauma patients and assessing transfusion efficacy by rotational thromboelastometry (ROTEM). As fibrinogen is affected by PI of WB, the effect of fibrinogen supplementation commonly used in trauma patients was also analyzed in this model.

STUDY DESIGN AND METHODS

Trauma transfusion scenarios were simulated by mixing untreated WB or WB treated with the Mirasol PI technology (riboflavin/UV) in different ratios with hemodiluted blood, and the thromboelasticity was monitored by ROTEM. The impact of supplementation with the fibrinogen concentrate RiaSTAP was investigated in this model.

RESULTS

Pathogen-inactivated WB (PI-WB) showed decreased activity in the hemostatic profile compared to the untreated control. Hemodiluted blood at a hematocrit (hct) of 20%, which was reconstituted with PI-WB or untreated WB, exhibited increased alpha values, maximum clot firmness, and clot formation time. Simulating transfusion scenarios by blood replacement with PI-WB resulted in a significant difference in ROTEM parameters between reconstituted PI-treated and -untreated WB (p ≥ .05). The effect of PI treatment waned when PI-WB was enriched with fibrinogen.

CONCLUSION

ROTEM investigations suggest that PI treatment has a negative impact on WB clot formation unless fibrinogen supplementation is used.

Inactivation of Plasmodium falciparum in whole blood using the amustaline and glutathione pathogen reduction technology

BACKGROUND

Risk of transfusion-transmitted (TT) malaria is mainly associated with whole blood (WB) or red blood cell (RBC) transfusion. Risk mitigation relies mostly on donor deferral while a limited number of countries perform blood testing, both negatively impacting blood availability. This study investigated the efficacy of the pathogen reduction system using amustaline and glutathione (GSH) to inactivate Plasmodium falciparum in WB.

STUDY DESIGN AND METHODS

WB units were spiked with ring stage P. falciparum infected RBCs. Parasite loads were measured in samples at time of infection, after 24 hours at room temperature (RT), and after a 24-hour incubation at RT post-treatment with 0.2 mM amustaline and 2 mM GSH. Serial 10-fold dilutions of the samples were inoculated to RBC cultures and maintained up to 4 weeks. Parasitemia was quantified by cytometry.

RESULTS

The P. falciparum viability assay has a limit of detection of a single live parasite per sample. Input parasite titer was >5.7 log10 TCID50 per mL. A 24-hour incubation at RT paused parasite development in controls, but they retained viability and infectivity when tested in culture. In contrast, no infectious parasites were detected in the amustaline/GSH-treated sample after 4 weeks of culture.

CONCLUSION

A robust level of P. falciparum inactivation was achieved in WB using amustaline/GSH treatment. Parasite log reduction was >5.7 log10 TCID50 per mL. Development of such a pathogen reduction system may provide an opportunity to reduce the risk of TT malaria and improve blood availability.

Evaluation of riboflavin photochemical treatment for inactivation of HCT116 tumor cells mixed in simulative intraoperative salvage blood

BACKGROUND

Radiation and filtration have achieved satisfactory results in inactivation or removal of tumor cells mixed in salvage blood, but some drawbacks remain. This study evaluated the inactivation on HCT116 cells mixed in simulative salvage blood by riboflavin photochemical treatment.

METHODS

HCT116 cells were added to the whole blood to simulate contaminated salvaged blood. The mixed blood was added with riboflavin of 50 μmol/L final concentration and illuminated by ultraviolet light. The samples were divided into control group and Experimental Groups 1 (18 J/cm² ), 2 (23.4 J/cm² ), and 3 (28.8 J/cm² ). An autotransfusion system (Cell Saver Elite, Haemonetics) was used to simulate the intraoperative blood salvage procedure to deal with whole blood. The apoptosis rate and tumorigenicity of HCT116 cells and the superimposed damage to red blood cells (RBCs) were evaluated.

RESULTS

The apoptosis rates of HCT116 in Experimental Groups 1, 2, and 3 were much higher than that in the control group. Tumor growth was found in the control group, but no tumor growth was found in the three experimental groups. The hemolysis rates in the three experimental groups were significantly higher than that in the control group, but much lower than the quality standard of RBCs at the end of preservation. The concentration of adenosine triphosphate in RBCs was comparable in the control and experimental groups.

CONCLUSION

Riboflavin at a 50 μmol/L final concentration and 18 J/cm² ultraviolet illumination can effectively inactivate HCT116 cells in salvaged blood, with minimum damage to the structure and function of RBCs, and the main quality indexes of salvaged RBCs were within the standard range.

Pathogen reduction of whole blood: utility and feasibility

OBJECTIVES

To collect information on pathogen reduction applied to whole blood.

BACKGROUND

Pathogen reduction (PR) of blood components has been developed over the past two decades, and pathogen-reduced fresh-frozen plasma and platelet concentrates are currently in clinical use. High cost and incomplete coverage of components make PR out of reach for low- and middle-income countries (LMIC). However, should PR become applicable to whole blood (WB), the main product transfused in sub-Saharan Africa, and be compatible with the preparation of clinically suitable components, cost would be minimised, and a range of safety measures in place at high cost in developed areas would become redundant.

METHODS

All articles called with "pathogen reduction", "pathogen inactivation" and "whole blood" were retrieved from Medline. References in articles were utilised.

RESULTS

One such PR technology (PRT) applied to WB has been developed and has shown efficacious against viruses, bacteria and parasites in vitro; and has been able to inactivate nucleated blood cells whilst retaining the ability to prepare components with acceptable characteristics. The efficacy of this WB PRT has been demonstrated in vivo using the inactivation of Plasmodium falciparum as a model and showing a high degree of correlation between in vitro and in vivo data. Obtaining further evidence of efficacy on other suitable targets is warranted. Shortening of the process, which is currently around 50 min, or increasing the number of units simultaneously processed would be necessary to make PRT WB conducive to LMIC blood services' needs.

CONCLUSIONS

Even if not 100% effective against agents that are present in high pathogen load titres, WB PRT could massively impact blood safety in LMIC by providing safer products at an affordable cost.

Red blood cells derived from whole blood treated with riboflavin and ultraviolet light maintain adequate survival in vivo after 21 days of storage

BACKGROUND

Pathogen reduction (PR) of whole blood (WB) may increase blood safety when applied before component separation. This study evaluates the in vivo performance of red blood cells (RBCs) derived from WB treated with the riboflavin and ultraviolet (UV) light PR (Mirasol) system.

STUDY DESIGN AND METHODS

This was a prospective, two-center, single-blind, randomized, two-period, crossover clinical trial designed to evaluate autologous ⁵¹ Cr/^99m Tc-radiolabeled recovery and survival of RBCs derived from Mirasol-treated WB compared to untreated WB. RBCs were stored in AS-3 for 21 days at 1 to 6°C. In vitro RBC variables were characterized. Frequency and severity of treatment-emergent adverse event (TEAE) and neoantigenicity were determined.

RESULTS

Twenty-four healthy adult volunteers (n = 12 per site) were evaluated. The Mirasol 24-hr RBC recoveries were 82.5 ± 3.9% with one-sided 95% lower confidence limit of 80.9%, meeting US Food and Drug Administration acceptance criteria, albeit at lower level than controls (91.7 ± 6.8%, p < 0.001). Mean RBC survival and T₅₀ were reduced in the Mirasol group (61 and 23 days, respectively) versus controls (82 and 36 days, respectively; p < 0.001) with a mean area under the curve survival of treated RBCs of 83% of untreated controls. End-of-storage hemolysis in the Mirasol group was 0.22 ± 0.1% (control, 0.15 ± 0.1%; p < 0.001). No neoantigenicity or differences in TEAEs were found.

CONCLUSION

RBCs derived from Mirasol WB and stored for up to 21 days in AS-3 maintained acceptable cell quality and recovery, albeit modestly reduced compared with untreated RBCs. Mirasol WB may represent a valid single WB PR platform that allows manufacture of RBC for storage for up to 21 days.

Targeting of blood safety measures to affected areas with ongoing local transmission of malaria

An outbreak of locally acquired Plasmodium vivax malaria in Greece started in 2009 and peaked in 2011. Targeting of blood safety measures to affected areas with ongoing transmission of malaria raised questions of how to define spatial boundaries of such an area and when to trigger any specific blood safety measures, including whether and which blood donation screening strategy to apply. To provide scientific advice the European Centre for Disease Prevention and Control (ECDC) organised expert meetings in 2013. The outcomes of these consultations are expert opinions covering spatial targeting of blood safety measures to affected areas with ongoing local transmission of malaria and blood donation screening strategy for evidence of malaria infection in these areas. Opinions could help EU national blood safety authorities in developing a preventive strategy during malaria outbreaks.

Treatment of Whole Blood With Riboflavin and UV Light: Impact on Malaria Parasite Viability and Whole Blood Storage

Background: Sub-Saharan African countries utilize whole blood (WB) to treat severe anemia secondary to severe blood loss or malaria on an emergency basis. In many areas with high prevalence of transfusion-transmissible agents, blood safety measures are insufficient. Pathogen reduction technology applied to WB might considerably improve blood safety. Methods: Whole blood from 40 different donors were treated with riboflavin and UV light (pathogen reduction technology) in order to inactivate malaria parasite replication. The extent of parasite inactivation was determined using quantitative polymerase chain reaction methods and was correlated to studies evaluating the replication of malaria parasites in culture. Products were also stored for 21 days at +4°C and monitored for cell quality throughout storage. Results: Plasmodium amplicon was present in 21 samples (>100 copies/mL), doubtful in four (10–100 genome equivalents [gEq]/mL), and negative in 15 U. The majority of asymptomatic parasitemic donors carried low parasite levels, with only six donors above 5,000 copies/mL (15%). After treatment with riboflavin and UV light, these six samples demonstrated a 0.5 to 1.2 log reduction in quantitative polymerase chain reaction amplification. This correlated to equal to or greater than 6.4 log reductions in infectivity. In treated WB units, cell quality parameters remained stable; however, plasma hemoglobin increased to 0.15 g/dL. All markers behaved similarly to published data for stored, untreated WB. Conclusions: Pathogen reduction technology treatment can inactivate malaria parasites in WB while maintaining adequate blood quality during posttreatment cold storage for 21 days.

Effect of Plasmodium inactivation in whole blood on the incidence of blood transfusion-transmitted malaria in endemic regions: the African Investigation of the Mirasol System (AIMS) randomised controlled trial

BACKGROUND

Transfusion-transmitted malaria is a frequent but neglected adverse event in Ghana. We did a randomised controlled clinical trial to assess the efficacy and safety of a whole blood pathogen reduction technology at preventing transfusion transmission of Plasmodium spp parasites.

METHODS

For this randomised, double-blind, parallel-group clinical trial, eligible adult patients (aged ≥ 18 years) with blood group O+, who required up to two whole blood unit transfusions within 3 days of randomisation and were anticipated to remain in hospital for at least 3 consecutive days after initial transfusion, were enrolled from Komfo Anokye Teaching Hospital in Kumasi, Ghana. The main exclusion criteria were symptoms of clinical malaria, antimalaria treatment within 7 days before randomisation, fever, and haemorrhage expected to require transfusion with up to two units of whole blood during the 3 days following study entry. Eligible patients were randomly assigned 1:1 by computer-generated permuted block randomisation (block size four) list to receive transfusion with either pathogen-reduced whole blood (treated) or whole blood prepared and transfused by standard local practice (untreated). Patients, health-care providers, and data collectors were masked to treatment allocation. Patients in both groups received up to two whole blood unit transfusions that were retrospectively tested for parasitaemia. Pre-transfusion and post-transfusion blood samples (taken on days 0, 1, 3, 7, and 28) were tested for presence and amount of parasite genome, and assessed for haematological and biochemical parameters. The primary endpoint was the incidence of transfusion-transmitted malaria in non-parasitaemic recipients exposed to parasitaemic whole blood, defined as two consecutive parasitaemic post-transfusion samples with parasite allelic matching, assessed at 1-7 days after transfusion. Secondary endpoints included haematological parameters and a safety analysis of adverse events in patients. This study is registered with ClinicalTrials.gov, number NCT02118428, and with the Pan African Clinical Trials Registry, number PACTR201406000777310.

FINDINGS

Between March 12, 2014, and Nov 7, 2014, 227 patients were enrolled into the study, one of whom was subsequently excluded because she did not meet the inclusion criteria. Of the 226 randomised patients, 113 were allocated to receive treated whole blood and 113 to receive standard untreated whole blood. 223 patients (111 treated and 112 untreated) received study-related transfusions, whereas three patients (two treated and one untreated) did not. 214 patients (107 treated and 107 untreated) completed the protocol as planned and comprised the per-protocol population. Overall, 65 non-parasitaemic patients (28 treated and 37 untreated) were exposed to parasitaemic blood. The incidence of transfusion-transmitted malaria was significantly lower for the pathogen-reduced (treated) patients (1 [4%] of 28 patients) than the untreated group (8 [22%] of 37 patients) in this population (p=0.039). Overall, 92 (41%) of 223 patients reported 145 treatment-related emergent adverse events during the conduct of the study, with a similar incidence of adverse events between groups receiving untreated or treated whole blood. No transfusion-related deaths occurred in the trial.

INTERPRETATION

Treatment of whole blood with the Mirasol pathogen reduction system for whole blood reduced the incidence of transfusion-transmitted malaria. The primary endpoint of the study was achieved in the population of non-parasitaemic patients receiving parasitaemic whole blood. The safety profile and clinical outcomes were similar across the two treatment groups.

FUNDING

Terumo BCT Inc.

Risks associated with red blood cell transfusions: potential benefits from application of pathogen inactivation

BACKGROUND

Red blood cell (RBC) transfusion risks could be reduced if a robust technology for pathogen inactivation of RBC (PI-RBCs) were to be approved.

MATERIALS AND METHODS

Estimates of per-unit and per-patient aggregate infectious risks for conventional RBCs were calculated; the latter used patient diagnosis as a determinant of estimated lifetime exposure to RBC units. Existing in vitro data for the two technologies under development for producing PI-RBCs and the status of current clinical trials are reviewed.

RESULTS

Minimum and maximum per-unit risk were calculated as 0.0003% (1 in 323,000) and 0.12% (1 in 831), respectively. The minimum estimate is for known lower-risk pathogens while the maximal estimate also includes an emerging infectious agent (EIA) and endemic area Babesia risk. Minimum and maximum per-patient lifetime risks by diagnosis grouping were estimated as 1.5 and 3.3%, respectively, for stem cell transplantation (which includes additional risk for cytomegalovirus transmission); 1.2 and 3.7%, respectively, for myelodysplastic syndrome; and 0.2 and 44%, respectively, for hemoglobinopathy.

DISCUSSION

There is potential for PI technologies to reduce infectious RBC risk and to provide additional benefits (e.g., prevention of transfusion-associated graft-versus-host disease and possible reduction of alloimmunization) due to white blood cell inactivation. PI-RBCs should be viewed in the context of having a fully PI-treated blood supply, enabling a blood safety paradigm shift from reactive to proactive. Providing insurance against new EIAs. Further, when approved, the use of PI for all components may catalyze operational changes in blood donor screening, laboratory testing, and component manufacturing.

Whole blood treated with riboflavin and ultraviolet light: quality assessment of all blood components produced by the buffy coat method

BACKGROUND

Pathogen inactivation (PI) technologies are currently licensed for use with platelet (PLT) and plasma components. Treatment of whole blood (WB) would be of benefit to the blood banking community by saving time and costs compared to individual component treatment. However, no paired, pool-and-split study directly assessing the impact of WB PI on the subsequently produced components has yet been reported.

STUDY DESIGN AND METHODS

In a "pool-and-split" study, WB either was treated with riboflavin and ultraviolet (UV) light or was kept untreated as control. The buffy coat (BC) method produced plasma, PLT, and red blood cell (RBC) components. PLT units arising from the untreated WB study arm were treated with riboflavin and UV light on day of production and compared to PLT concentrates (PCs) produced from the treated WB units. A panel of common in vitro variables for the three types of components was used to monitor quality throughout their respective storage periods.

RESULTS

PCs derived from the WB PI treatment were of significantly better quality than treated PLT components for most variables. RBCs produced from the WB treatment deteriorated earlier during storage than untreated units. Plasma components showed a 3% to 44% loss in activity for several clotting factors.

CONCLUSION

Treatment of WB with riboflavin and UV before production of components by the BC method shows a negative impact on all three blood components. PLT units produced from PI-treated WB exhibited less damage compared to PLT component treatment.

Chemical and biological mechanisms of pathogen reduction technologies

Within the last decade new technologies have been developed and implemented which employ light, often in the presence of a photosensitizer, to inactivate pathogens that reside in human blood products for the purpose of transfusion. These pathogen reduction technologies attempt to find the proper balance between pathogen kill and cell quality. Each system utilizes various chemistries that not only impact which pathogens they can inactivate and how, but also how the treatments affect the plasma and cellular proteins and to what degree. This paper aims to present the various chemical mechanisms for pathogen reduction in transfusion medicine that are currently practiced or in development.

Pathogen inactivation technologies for cellular blood components: an update

Nowadays patients receiving blood components are exposed to much less transfusion-transmitted infectious diseases than three decades before when among others HIV was identified as causative agent for the acquired immunodeficiency syndrome and the transmission by blood or coagulation factors became evident. Since that time the implementation of measures for risk prevention and safety precaution was socially and politically accepted. Currently emerging pathogens like arboviruses and the well-known bacterial contamination of platelet concentrates still remain major concerns of blood safety with important clinical consequences, but very rarely with fatal outcome for the blood recipient. In contrast to the well-established pathogen inactivation strategies for fresh frozen plasma using the solvent-detergent procedure or methylene blue and visible light, the bench-to-bedside translation of novel pathogen inactivation technologies for cell-containing blood components such as platelets and red blood cells are still underway. This review summarizes the pharmacological/toxicological assessment and the inactivation efficacy against viruses, bacteria, and protozoa of each of the currently available pathogen inactivation technologies and highlights the impact of the results obtained from several randomized clinical trials and hemovigilance data. Until now in some European countries pathogen inactivation technologies are in in routine use for single-donor plasma and platelets. The invention and adaption of pathogen inactivation technologies for red blood cell units and whole blood donations suggest the universal applicability of these technologies and foster a paradigm shift in the manufacturing of safe blood.

Development of a mitochondrial DNA real-time polymerase chain reaction assay for quality control of pathogen reduction with riboflavin and ultraviolet light

BACKGROUND AND OBJECTIVES

Transfusion is associated with a risk of infection and alloimmunization. Pathogen reduction using riboflavin and UV light (Mirasol treatment) inactivates pathogens and leucocytes. With increasing adoption of the technology in clinical use, regulatory agencies have recommended the introduction of quality control measures to monitor pathogen reduction efficacy. We sought to develop a real-time PCR-based assay to document the impact of pathogen reduction on the mitochondrial genome in blood components.

MATERIALS AND METHODS

DNA was extracted from platelet and plasma components before and after treatment with riboflavin and UV light. Inhibition of PCR amplification of mitochondrial DNA (mtDNA) in short- and long-amplicon target regions, ranging from under 200 base pairs (bp) to over 1800 bp, was measured in treated relative to untreated components.

RESULTS

Pathogen reduction of platelets using riboflavin and UV light resulted in inhibition of PCR amplification of long-amplicon mtDNA targets, demonstrating approximately 1 log reduction of amplification relative to untreated products. Amplification of short-amplicon mtDNA targets was not affected by treatment. Evaluation of 110 blinded platelet samples from the PREPAReS clinical trial resulted in prediction of treatment status with 100% accuracy. Pathogen reduction of plasma components resulted in similar levels of PCR inhibition, while testing of 30 blinded plasma samples resulted in prediction of treatment status with 93% accuracy.

CONCLUSION

A differential sized amplicon real-time PCR assay of mitochondrial DNA effectively documents nucleic acid damage induced by Mirasol treatment of platelets. The use of the assay for plasma product pathogen reduction requires further investigation.

Plasmodium genome in blood donors at risk for malaria after several years of residence in Italy

BACKGROUND

At present, the main risk of transfusion-transmitted malaria (TTM) in nonendemic countries is chronic, asymptomatic immigrants from malaria-endemic areas. Semi-immune donors may carry undetected parasitemia. This study examines Plasmodium infection in at-risk blood donors in Northern Italy.

STUDY DESIGN AND METHODS

Plasma samples from 97 candidate donors and 80 controls were tested for malarial antibodies using a commercial enzyme immunoassay. The conserved 18S rRNA and the mitochondrial genes of Plasmodium were amplified to detect and quantify parasite genomes (copies/mL). Plasmodium species were identified with a species-specific nested polymerase chain reaction. Parasitemic samples were further tested by amplification of polymorphic repetitive regions in MSP-1 Block 2, MSP-2 Block 3, and glutamate-rich protein (GLURP) confirmed by sequencing.

RESULTS

Three of 83 seropositive (3.6%) and one of 14 seronegative at-risk candidate donors carried Plasmodium genome (4 × 10(3) -8.5 × 10(4) copies/mL): two P. falciparum, one P. malariae (seronegative sample), and one coinfection with P. malariae and P. ovale. Alleles of MSP-1 (MAD20 and K1), MSP-2 (3D7 and FC27), and GLURP were amplified from Sample 261. In Sample 282 only one allele in MSP-2 (FC27) and GLURP was amplified. No alleles were detected in Samples 283 and 331.

CONCLUSIONS

Immigrants from endemic countries might carry infectious Plasmodium after 2 to 5 years of continuous residence in Italy. Serologic screening may miss donors carrying P. malariae. Permanent exclusion or screening for both antibodies and genome are needed to prevent TTM.

Emerging Pathogens - How Safe is Blood?

During the last few decades, blood safety efforts were mainly focused on preventing viral infections. However, humanity's increased mobility and improved migration pathways necessitate a global perspective regarding other transfusion-transmitted pathogens. This review focuses on the general infection risk of blood components for malaria, dengue virus, Trypanosoma cruzi (Chagas disease) and Babesia spp. Approximately 250 million people become infected by Plasmodium spp. per year. Dengue virus affects more than 50 million people annually in more than 100 countries; clinically, it can cause serious diseases, such as dengue haemorrhagic fever and dengue shock syndrome. Chagas disease, which is caused by Trypanosoma cruzi, mainly occurs in South America and infects approximately 10 million people annually. Babesia spp. is a parasitic infection that infects red blood cells; although many infections are asymptomatic, severe clinical disease has been reported, especially in the elderly. Screening assays are available for all considered pathogens but make screening strategies more complex and more expensive. A general pathogen inactivation for all blood components (whole blood) promises to be a long-term, sustainable solution for both known and unknown pathogens. Transfusion medicine therefore eagerly awaits such a system.