Transfusion-Transmitted Dengue and Associated Clinical Symptoms During the 2012 Epidemic in Brazil

Identification and characterization of permissive cells to dengue virus infection in human hematopoietic stem and progenitor cells

BACKGROUND

Dengue virus (DENV) is a significant threat to public health in tropical and subtropical regions, where the frequency of human migration is increasing. Transmission of DENV from donors to recipients after hematopoietic stem cell transplantation has been steadily described. However, the underlying mechanisms remain unclear.

STUDY DESIGN AND METHODS

Freshly isolated bone marrow (BM) was subjected to DENV infection, followed by multicolor fluorescence-activated cell sorting (FACS) analysis. Virus in supernatants was collected and analyzed by plaque assay.

RESULTS

DENV-1 to DENV-4 could effectively infect freshly obtained BM and produced infectious virus. DENV infection did not change the quantitative population of hematopoietic stem and progenitor cells (HSPCs), megakaryocytic progenitor cells (MkPs) and megakaryocytes. Additionally, DENV antigen, nonstructural protein 1, was enriched in HSPCs and MkPs of DENV infected marrow cells. CD34+, CD133+, or CD61+ cells sorted out from BM were not only the major contributing targets facilitating the DENV infection directly but also facilitated the spread of DENV into other cells when cocultured.

CONCLUSION

Results suggest that DENV can efficiently infect HSPCs, which might jeopardize the recipients if DENV-infected cells were subsequently used. We therefore raise the need for DENV screening for both the donors and recipients of hematopoietic stem cell transplantation, especially for donors exposed to endemic areas, to mitigate DENV infection in immunocompromised recipients.

The Potential Impact of Chikungunya Virus Outbreaks on Blood Transfusion

Chikungunya virus (CHIKV) is responsible for large periodic epidemics in both endemic and nonendemic areas where competent mosquitoes are present. Transmission of CHIKV by transfusion during explosive outbreaks has never been documented, and the true impact of CHIKV infection on blood transfusion during an outbreak is unknown. Considerations include not only transfusions in the active outbreak areas but also returning travelers to nonendemic areas. Because there are no documented cases of transfusion-transmitted CHIKV, there are no standard guidelines regarding transfusion policies during a chikungunya fever outbreak. We review current information from studies during outbreaks with the goal of estimating the potential effect of different blood safety interventions (eg, querying donors for possible CHIKV exposure, chikungunya fever-related symptoms, screening for CHIKV RNA).

Dengue virus transmission from live donor liver graft

Arboviral transmission through transplanted organs is rare. We report a highly probable case of dengue viral transmission during live donor liver transplantation. Fever with severe thrombocytopenia was observed in the donor and recipient within 6 and 9 days after transplantation, respectively. Dengue diagnosis was confirmed by testing blood and explant tissue from the donor and recipient using dengue-specific NAT (nucleic acid testing) and serology. Serology indicated the donor had secondary dengue infection that ran a mild course. However, the dengue illness in the recipient was severe and deteriorated rapidly, eventually proving fatal. The recipient's explant liver tissue tested negative for viral RNA indicative of a pretransplant naïve status. The prM-Envelope gene sequence analysis of the donor and recipient viral RNA identified a similar serotype (DENV1) with almost 100% sequence identity in the envelope region. Molecular phylogenetic analysis of donor and recipient viral envelope sequences with regional and local dengue strains further confirmed their molecular similarity, suggesting a probable donor-to-recipient transmission via organ transplantation. Screening of living donors for dengue virus may be considered in endemic regions.

Critical developments of 2018: A review of the literature from selected topics in transfusion. A committee report from the AABB's Clinical Transfusion Medicine Committee

BACKGROUND

The AABB compiles an annual synopsis of the published literature covering important developments in the field of transfusion medicine. An abridged version of this work is being made available in TRANSFUSION, with the full-length report available as Appendix S1 (available as supporting information in the online version of this paper).

STUDY DESIGN AND METHODS

Papers published in late 2017 and 2018 are included, as well as earlier papers cited for background. Although this synopsis is comprehensive, it is not exhaustive, and some papers may have been excluded or missed.

RESULTS

The following topics are covered: "big data" and "omics" studies, emerging infections and testing, platelet transfusion and pathogen reduction, transfusion therapy and coagulation, transfusion approach to hemorrhagic shock and mass casualties, therapeutic apheresis, and chimeric antigen receptor T-cell therapy.

CONCLUSION

This synopsis may be a useful educational tool.

Emergent Arboviruses and Renal Transplantation: A Global Challenge

In recent years, Zika, Chikungunya, Dengue, West Nile Fever, and Yellow Fever epidemics have generated some concerns. Besides difficulties related to vector control, there are challenges related to behavior of pathologies not yet fully understood. The transplanted population requires additional care due to immunosuppressive drugs. Furthermore, the potential risk of transmission during donation is another source of uncertainty and generates debate among nephrologists in transplant centers. Do the clinical outcomes and prognoses of these infections tend to be more aggressive in this population? Is there a risk of viral transmission via kidney donation? In this review article, we address these issues and discuss the relationship between arbovirus and renal transplantation.

Dengue seroprevalence among asymptomatic blood donors during an epidemic outbreak in Central-West Brazil

Dengue virus (DENV) transmission by blood transfusion is an important route of viral acquisition during outbreaks. The prevalence of DENV markers (viral RNA, NS1, anti-DENV IgM, and IgG) among blood donors in Central-West Brazil has never been evaluated. Our aim was to evaluate the full set of serological and molecular markers for DENV among blood donors of the Federal District of Brazil during an extensive outbreak in 2016. We found an anti-DENV IgM prevalence of 6.74% (n = 32/475). Of 475, 20 samples (4.21%) were also anti-DENV IgG positive. All samples were non-reactive for NS1 and DENV RNA. Our results imply that a significant proportion of the tested donors had experienced asymptomatic infection. More studies are necessary to evaluate the real prevalence of DENV viremia in blood donors from the Federal District of Brazil and if specific measures are needed to routinely test the blood donors for DENV RNA during outbreaks.

Prevention of transfusion-transmitted infections

Since the 1970s, introduction of serological assays targeting virus-specific antibodies and antigens has been effective in identifying blood donations infected with the classic transfusion-transmitted infectious agents (TTIs; hepatitis B virus [HBV], HIV, human T-cell lymphotropic virus types I and II, hepatitis C virus [HCV]). Subsequently, progressive implementation of nucleic acid-amplification technology (NAT) screening for HIV, HCV, and HBV has reduced the residual risk of infectious-window-period donations, such that per unit risks are <1 in 1 000 000 in the United States, other high-income countries, and in high-incidence regions performing NAT. NAT screening has emerged as the preferred option for detection of newer TTIs including West Nile virus, Zika virus (ZIKV), and Babesia microti Although there is continual need to monitor current risks due to established TTI, ongoing challenges in blood safety relate primarily to surveillance for emerging agents coupled with development of rapid response mechanisms when such agents are identified. Recent progress in development and implementation of pathogen-reduction technologies (PRTs) provide the opportunity for proactive rather than reactive response to blood-safety threats. Risk-based decision-making tools and cost-effectiveness models have proved useful to quantify infectious risks and place new interventions in context. However, as evidenced by the 2015 to 2017 ZIKV pandemic, a level of tolerable risk has yet to be defined in such a way that conflicting factors (eg, theoretical recipient risk, blood availability, cost, and commercial interests) can be reconciled. A unified approach to TTIs is needed, whereby novel tests and PRTs replace, rather than add to, existing interventions, thereby ameliorating cost and logistical burden to blood centers and hospitals.

Screening the Blood Supply for Zika Virus in the 50 U.S. States and Puerto Rico: A Cost-Effectiveness Analysis

BACKGROUND

In 2016, universal individual donation nucleic acid testing (ID-NAT) of donated blood for Zika virus began in U.S. states and territories.

OBJECTIVE

To assess the cost-effectiveness of universal ID-NAT in the first year of screening compared with alternatives for the 50 states and separately for Puerto Rico.

DESIGN

Microsimulation that captured Zika-related harms to transfusion recipients, sexual partners, and their infants.

DATA SOURCES

National testing results compiled by AABB and costs, utilities, and outcome probabilities estimated from the literature.

TARGET POPULATION

Transfusion recipients.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTION

Universal ID-NAT, universal mini-pool NAT (MP-NAT), and ID-NAT exclusively for components transfused to women of childbearing age. Seasonally targeted strategies in Puerto Rico and geographically targeted strategies in the 50 states were also considered.

OUTCOME MEASURES

Costs, quality-adjusted life-years (QALYs), and outcomes.

RESULTS OF BASE-CASE ANALYSIS

In Puerto Rico, MP-NAT exclusively during high mosquito season was cost-effective at $81 123 per QALY (95% CI, -$49 138 to $978 242 per QALY). No screening policy was cost-effective in the 50 states. Universal ID-NAT cost $341 million per QALY (CI, $125 million to $2.90 billion per QALY) compared with no screening in the 50 states.

RESULTS OF SENSITIVITY ANALYSIS

In Puerto Rico, MP-NAT only during the season of high mosquito activity was most cost-effective in 64% of probabilistic sensitivity analysis iterations. In the 50 states, no intervention was cost-effective in 99.99% of iterations. Cost-effectiveness was highly dependent on the rate of assumed infectious donations.

LIMITATION

Data were limited on the component-specific transmissibility of Zika and long-term sequelae of infection.

CONCLUSION

Screening was cost-effective only in the high mosquito season in Puerto Rico, and no evaluated screening policy was cost-effective in the 50 states. During periods with lower rates of Zika-infectious donations, the cost-effectiveness of screening will be even less favorable.

PRIMARY FUNDING SOURCE

None.

Dengue

Mortality from severe dengue is low, but the economic and resource burden on health services remains substantial in endemic settings. Unfortunately, progress towards development of effective therapeutics has been slow, despite notable advances in the understanding of disease pathogenesis and considerable investment in antiviral drug discovery. For decades antibody-dependent enhancement has been the prevalent model to explain dengue pathogenesis, but it was only recently demonstrated in vivo and in clinical studies. At present, the current mainstay of management for most symptomatic dengue patients remains careful observation and prompt but judicious use of intravenous hydration therapy for those with substantial vascular leakage. Various new promising technologies for diagnosis of dengue are currently in the pipeline. New sample-in, answer-out nucleic acid amplification technologies for point-of-care use are being developed to improve performance over current technologies, with the potential to test for multiple pathogens using a single specimen. The search for biomarkers that reliably predict development of severe dengue among symptomatic individuals is also a major focus of current research efforts. The first dengue vaccine was licensed in 2015 but its performance depends on serostatus. There is an urgent need to identify correlates of both vaccine protection and disease enhancement. A crucial assessment of vector control tools should guide a research agenda for determining the most effective interventions, and how to best combine state-of-the-art vector control with vaccination.

Asymptomatic dengue virus cases in misiones, Argentina: a seroprevalence study in the university population

Dengue infection may be asymptomatic and may produce the typical symptoms of a benign illness or serious hemorrhagic and often fatal symptoms. Asymptomatic cases are statistically relevant and quite variable depending on the geographic area under study. However, there are no reports of asymptomatic population infected by the dengue virus in Misiones. In this study, 288 samples were analyzed, and the IgG anti dengue antibodies detected accounted for 6.6% of cases, while 89% corresponded to individuals who lived with people diagnosed or suspected of having contracted dengue, p= <0.001.

Duplex nucleic acid test for the detection of chikungunya and dengue RNA viruses in blood donations

BACKGROUND

Chikungunya (CHIKV) and dengue (DENV) viruses are primarily mosquito‐borne, but transfusion transmission can occur (DENV) or is likely (CHIKV). In the absence of commercially available blood screening assays, a variety of strategies to ensure recipient safety in the face of expanding CHIKV and/or DENV outbreaks have been used.

STUDY DESIGN AND METHODS

Performance of cobas CHIKV/DENV, a qualitative RNA detection assay for use on the cobas 6800/8800 Systems, was evaluated at two sites (Roche Molecular Systems, Inc. [RMS], and the American Red Cross [ARC]). Analytical sensitivity, genotype inclusion, correlation with other assays, and reproducibility used clinical CHIKV‐ or DENV‐positive samples and secondary standards for DENV Types 1 to 4 and for three CHIKV genotypes (Asian; East Central South African; and West African); each secondary standard was traceable to international reference panels or reagents. Evaluation of analytic specificity assessed other microorganisms for interference and cross‐reactivity; clinical specificity was determined by individually testing 10,528 volunteer blood donations from the continental United States.

RESULTS

The 50 and 95% limit of detection (LoD) obtained by RMS for CHIKV, Asian genotype was 1.8 and 6.8 Detectable Units (DU)/mL, respectively, and 0.14 and 0.63 International Units (IU)/mL, respectively for DENV‐1. No significant differences in detection occurred by testing at a second site, the ARC (2.4 and 10.5 DU/mL for CHIKV and 0.15 and 0.60 IU/mL for DENV). Clinical specificity was 100% (95% confidence interval, 99.965%‐100%) for CHIKV and DENV.

CONCLUSIONS

The high sensitivity and specificity of the cobas CHIKV/DENV test, as demonstrated in these evaluations, indicate its suitability for blood donation screening.

The Emergence of Zoonotic Pathogens as Agents of Concern in Transfusion Medicine

A variety of emerging infections are of interest to transfusion medicine clinicians, but zoonotic pathogens, those maintained in nonhuman hosts and transmitted to humans, have dominated recent discussions, especially emerging acute viral infections that can or might spread around a shrinking globe with unprecedented speed, in an infected human or an infected vector or reservoir host. Further, advanced pathogen discovery techniques (e.g., metagenomics) allow the identification of potential pathogens before their recognition as clinically relevant to transfusion medicine. In the aftermath of our experiences with HIV and posttransfusion hepatitis, our windows for response to such agents and infections have contracted rapidly. These characteristics pose difficult challenges for our development of surveillance and control regimes capable of timely, but appropriately nuanced, responses. This monograph surveys a selection of such agents, exploring their apparent relevance to transfusion medicine, closing with a framework for an ongoing approach to their surveillance, recognition, threat evaluation, and mitigation.

Evaluation of anesthesiologists' knowledge about occupational health: Pilot study

BACKGROUND

An anesthesiologists' work presents with numerous occupational risks owing to the large amount of time spent inside the operating room where constant noise, anesthetic vapors, ionizing radiation, infectious agents, and psychological stress are present. Herein, we evaluated anesthesiologists' knowledge about occupational health.

METHODS

A cross-sectional study was conducted to assess 158 anesthesiologists from a tertiary hospital on their knowledge about occupational health using a structured questionnaire.

RESULTS

The survey revealed a lack of knowledge on the forms of prevention of occupational accidents (74.6% did not know how to act in case of a fire during surgery, 56% failed to identify the post-anesthesia care unit as the place with the highest contamination by inhalation anesthetics, and 42.7% failed to identify all personal protective equipment) and a surprisingly high rate of lack of observance of preventive measures (30.3% washed their hands before touching every patient, 52.5% did not use gloves during intravenous access, and 88.6% used protective equipment against ionizing radiation).

CONCLUSIONS

Despite improvements in safety standards in healthcare facilities, our research showed lack of knowledge about major topics on occupational health by physicians. Improving safety awareness is an important goal of training programs and continued medical education.

Risk of transfusion-associated dengue: screening of blood donors from Pune, western India

BACKGROUND

Dengue, a mosquito-borne viral disease, is endemic in >125 countries worldwide. The threat of blood-borne transmission of dengue virus (DENV) has been documented.

STUDY DESIGN AND METHODS

This study was conducted to assess the potential magnitude of transfusion-associated dengue, by determination of DENV seromarkers in blood donations from Pune, India, during two dengue seasons (2016 and 2017). These included DENV nonstructural protein 1 (NS1), anti-DENV immunoglobulin (Ig) M, anti-DENV IgG (enzyme-linked immunosorbent assay), and DENV RNA (reverse transcription-polymerase chain reaction).

RESULTS

NS1 (IgM) reactivity was 1 of 209, 0.48% (11/209, 5.3%) in 2016 and 2 of 311, 0.64% (20/311, 6.4%) in 2017. Of the 34 NS1/IgM reactives, 1 NS1-reactive donor and 10 IgM-reactive donors exhibited evidence of secondary infection. DENV RNA was not detected in any of the 34 NS1/IgM reactives. Among the NS1/IgM negatives, anti-DENV IgG reactivity was high in 2016 (75%) and further increased in 2017 (87%, p = 0.002).

CONCLUSION

Although RNA negative, detection of 34 NS1/IgM-reactive donations, of which 11 had evidence of secondary infection, suggests the need for further evaluation on the basis of potential risk to recipients of either dengue transmission or increased risk of secondary infection. These would include multicenter studies followed by cost-benefit analyses.

Low frequency of asymptomatic dengue virus-infected donors in blood donor centers during the largest dengue outbreak in Taiwan

To determine the prevalence of asymptomatic dengue virus-infected blood donors during the largest dengue outbreak in Taiwan history occurred in 2015, we examined the evidence of dengue virus (DENV) infection by the detection of DENV RNA genome using real-time reverse transcription-polymerase chain reaction (real-time RT-PCR), DENV NS1 antigen using rapid diagnosis test (RDT) and anti-dengue antibody using IgM/IgG capture enzyme-linked immunosorbent assay (capture ELISA) and RDT in eight thousand serum samples from blood donations to the blood centers of the Taiwan Blood Services Foundation (TBSF) in Kaohsiung City and Tainan City during the largest dengue outbreak in Taiwan history occurred in 2015. Only one serum sample was positive for DENV RNA detection by using dengue-specific real-time RT-PCR, the virus was DENV-2 determined by serotype-specific real-time RT-PCR and sequencing, and the DENVs in the serum were confirmed as being infectious by a plaque assay. The recipient of this blood did not develop any dengue fever symptom on follow-up. None of the samples was NS1 RDT-reactive. Seventeen IgM-positive samples were identified. There was a low prevalence of asymptomatic confirmed or probable DENV-infected blood donors in our study (0.013% and 0.21%, respectively), and no symptomatic transfusion-transmitted dengue (TT dengue) was developed during the largest dengue outbreak in Taiwan history in highly endemic areas and periods.

Clinical and genetic ancestry profile of a large multi-centre sickle cell disease cohort in Brazil

Approximately 3500 children with sickle cell disease (SCD) are born in Brazil each year, but the burden of SCD morbidity is not fully characterised. A large, multi-centre cohort was established to characterise clinical outcomes in the Brazilian SCD population and create the infrastructure to perform genotype-phenotype association studies. Eligible patients were randomly selected from participating sites and recruited at routine visits. A biorepository of blood samples was created and comprehensive demographic and clinical outcome data were entered in a centralized electronic database. Peripheral blood genome-wide single nucleotide polymorphism (SNP) genotyping was performed using a customized Transfusion Medicine (TM) Array. A total of 2795 participants at six Brazilian sites were enrolled between 2013 and 2015. The cohort included slight predominance of children <18 years (55·9%) and females (53·0%). Haemoglobin (Hb) SS was the most common SCD genotype (70·7%), followed by HbSC (23%), Sβ0 (3·0%) and Sβ+ (2·9%). SNP data from the TM Array were analysed to evaluate the genetic ancestry of the cohort and revealed significant admixture among the population. Demographics and clinical complications, stratified by age and SCD genotype, are summarized and future studies in this cohort are discussed.

[Ocular manifestations of emerging arboviruses: Dengue fever, Chikungunya, Zika virus, West Nile virus, and yellow fever (French translation of the article)]

Arboviruses are viral diseases transmitted by mosquitoes and tics bites. They are a major cause of morbidity and sometimes mortality. Their expansion is constant and due in part to climate change and globalization. Mostly found in tropical regions, arboviruses are sometimes the source of epidemics in Europe. Recently, the Chikungunya virus and the Zika virus were responsible for very large epidemics impacting populations that had never been in contact with those viruses. There are currently no effective antiviral treatments or vaccines. Ocular manifestations due to those infections are thus more frequent and increasingly better described. They are sometimes, as with Zika, complicated by a congenital ocular syndrome. The goal of this review is to describe the ophthalmological manifestations of Dengue fever, Chikungunya virus, Zika virus, West Nile virus, and yellow fever.

Ocular manifestations of emerging arboviruses: Dengue fever, Chikungunya, Zika virus, West Nile virus, and yellow fever

Arboviruses are viral diseases transmitted by mosquitoes and tick bites. They are a major cause of morbidity and sometimes mortality. Their expansion is constant and due in part to climate change and globalization. Mostly found in tropical regions, arboviruses are sometimes the source of epidemics in Europe. Recently, the Chikungunya virus and the Zika virus were responsible for very large epidemics impacting populations that had never been in contact with those viruses. There are currently no effective antiviral treatments or vaccines. Ocular manifestations due to those infections are thus more frequent and increasingly better described. They are sometimes, as with Zika, complicated by a congenital ocular syndrome. The goal of this review is to describe the ophthalmological manifestations of Dengue fever, Chikungunya virus, Zika virus, West Nile virus, and yellow fever.

Chikungunya, Dengue, and Zika in Immunocompromised Hosts

PURPOSE OF REVIEW

Describe the characteristics of chikungunya, dengue, and Zika in transplant recipients and immunocompromised hosts.

RECENT FINDINGS

Stem cell/bone marrow grafts, organs, and blood transfusions can transmit CHIKV/DENV/ZIKV infections, which are clinically similar, resembling influenza-like illness. Laboratory confirmation is necessary. In the acute phase, RT-PCR is preferred. DENV and ZIKV serology may cross-react. Delayed engraftment and extended viruria is observed in ZIKV+/HSCT recipients, while longer viremia is observed in DENV+/HSCT patients. Arbovirus persistence in organ tissues is generally unknown. Vaccine development is in early stages for CHIKV/ZIKV. No data is available to recommend the licensed DENV vaccine in transplant recipients. In endemic areas, the assessment of epidemiological risk is mandatory. Donor deferral for 120 days in suspected or confirmed ZIKV+ has been recommended, while CHIKV+ donors should wait 30 days. No deferral is recommended for DENV+ donors. CHIKV/DENV/ZIKV tests should be included in the differential of febrile neutropenia and other transplant syndromes. Reassessment of DENV serology is urgently needed. Prospective studies are necessary to determine the impact of CHIKV/DENV/ZIKV in this special population.

Emerging Infectious Agents and Blood Safety in Latin America

Historically, emerging infectious agents have been an important driving force toward the enhancement of blood safety, illustrated by the sharp reduction in the transmission of infectious agents by blood transfusion after human immunodeficiency virus (HIV) epidemics. In general, Latin American (LATAM) countries have introduced screening for microorganisms with proven blood transmission with some delay in comparison to developed countries, but, nowadays, all LATAM countries comply with a minimum standard of screening which includes Hepatitis B, C, HIV, Treponema pallidum, and Trypanosoma cruzi. Noticeably, all those agents, in addition to HTLV, cause chronic infections. By contrast, in the last decade, the region has witnessed explosive outbreaks of arboviral diseases, representing a new challenge to the blood system, threatening not only blood safety but also availability. So far, the clinical impact of transfusion-transmitted Dengue, Chikungunya, or Zika has not been evident, precluding immediate reaction from the authorities. A number of other arboviruses are endemic in the region and may, unpredictably, originate new epidemics. Several measures must be taken in preparedness for the potential emergence of another arbodisease.

Ross River virus in Australian blood donors: possible implications for blood transfusion safety

BACKGROUND

Emerging transfusion-transmissible pathogens, including arboviruses such as West Nile, Zika, dengue, and Ross River viruses, are potential threats to transfusion safety. The most prevalent arbovirus in humans in Australia is Ross River virus (RRV); however, prevalence varies substantially around the country. Modeling estimated a yearly risk of 8 to 11 potentially RRV-viremic fresh blood components nationwide. This study aimed to measure the occurrence of RRV viremia among donors who donated at Australian collection centers located in areas with significant RRV transmission during one peak season.

STUDY DESIGN AND METHODS

Plasma samples were collected from donors (n = 7500) who donated at the selected collection centers during one peak season. Viral RNA was extracted from individual samples, and quantitative reverse transcription-polymerase chain reaction was performed.

RESULTS

Regions with the highest rates of RRV transmission were not areas where donor centers were located. We did not detect RRV RNA among 7500 donations collected at the selected centers, resulting in a zero risk estimate with a one-sided 95% confidence interval of 0 to 1 in 2019 donations.

CONCLUSION

Our results suggest that the yearly risk of collecting a RRV-infected blood donation in Australia is low and is at the lower range of previous risk modeling. The majority of Australian donor centers were not in areas known to be at the highest risk for RRV transmission, which was not taken into account in previous models based on notification data. Therefore, we believe that the risk of RRV transfusion transmission in Australia is acceptably low and appropriately managed through existing risk management, including donation restrictions and recall policies.

Pathogen reduction and blood transfusion safety in Africa: strengths, limitations and challenges of implementation in low-resource settings

Transfusion-transmitted infection risk remains an enduring challenge to blood safety in Africa. A high background incidence and prevalence of the major transfusion-transmitted infections (TTIs), dependence on high-risk donors to meet demand, suboptimal testing and quality assurance collectively contribute to the increased risk. With few exceptions, donor testing is confined to serological evaluation of human immunodeficiency virus (HIV), hepatitis B and C (HBV and HCV) and syphilis. Barriers to implementation of broader molecular methods include cost, limited infrastructure and lack of technical expertise. Pathogen reduction (PR), a term used to describe a variety of methods (e.g. solvent detergent treatment or photochemical activation) that may be applied to blood following collection, offers the means to diminish the infectious potential of multiple pathogens simultaneously. This is effective against different classes of pathogen, including the major TTIs where laboratory screening is already implemented (e.g. HIV, HBV and HCV) as well pathogens that are widely endemic yet remain unaddressed (e.g. malaria, bacterial contamination). We sought to review the available and emerging PR techniques and their potential application to resource-constrained parts of Africa, focusing on the advantages and disadvantages of such technologies. PR has been slow to be adopted even in high-income countries, primarily given the high costs of use. Logistical considerations, particularly in low-resourced parts of Africa, also raise concerns about practicality. Nonetheless, PR offers a rational, innovative strategy to contend with TTIs; technologies in development may well present a viable complement or even alternative to targeted screening in the future.

Genomic and epidemiological characterisation of a dengue virus outbreak among blood donors in Brazil

Outbreaks caused by Dengue, Zika and Chikungunya viruses can spread rapidly in immunologically naïve populations. By analysing 92 newly generated viral genome sequences from blood donors and recipients, we assess the dynamics of dengue virus serotype 4 during the 2012 outbreak in Rio de Janeiro. Phylogenetic analysis indicates that the outbreak was caused by genotype II, although two isolates of genotype I were also detected for the first time in Rio de Janeiro. Evolutionary analysis and modelling estimates are congruent, indicating a reproduction number above 1 between January and June, and at least two thirds of infections being unnoticed. Modelling analysis suggests that viral transmission started in early January, which is consistent with multiple introductions, most likely from the northern states of Brazil, and with an increase in within-country air travel to Rio de Janeiro. The combination of genetic and epidemiological data from blood donor banks may be useful to anticipate epidemic spread of arboviruses.

Emerging infectious disease outbreaks: estimating disease risk in Australian blood donors travelling overseas

BACKGROUND AND OBJECTIVES

International travel assists spread of infectious pathogens. Australians regularly travel to South-eastern Asia and the isles of the South Pacific, where they may become infected with infectious agents, such as dengue (DENV), chikungunya (CHIKV) and Zika (ZIKV) viruses that pose a potential risk to transfusion safety. In Australia, donors are temporarily restricted from donating for fresh component manufacture following travel to many countries, including those in this study. We aimed to estimate the unmitigated transfusion-transmission (TT) risk from donors travelling internationally to areas affected by emerging infectious diseases.

MATERIALS AND METHODS

We used the European Up-Front Risk Assessment Tool, with travel and notification data, to estimate the TT risk from donors travelling to areas affected by disease outbreaks: Fiji (DENV), Bali (DENV), Phuket (DENV), Indonesia (CHIKV) and French Polynesia (ZIKV).

RESULTS

We predict minimal risk from travel, with the annual unmitigated risk of an infected component being released varying from 1 in 1·43 million to <1 in one billion and the risk of severe consequences ranging from 1 in 130 million to <1 in one billion.

CONCLUSION

The predicted unmitigated likelihood of infection in blood components manufactured from donors travelling to the above-mentioned areas was very low, with the possibility of severe consequences in a transfusion recipient even smaller. Given the increasing demand for plasma products in Australia, the current strategy of restricting donors returning from select infectious disease outbreak areas to source plasma collection provides a simple and effective risk management approach.

A review of selected Arboviruses during pregnancy

Arboviruses are emerging infectious diseases with the ability to expand geographically and rapidly affect large populations.

The recent epidemic caused by the Zika virus in the Americas and congenital Zika syndrome associated with maternal infection has called out attention to the importance of studying arboviruses during pregnancy.

This is a review on selected arboviruses infections during gestation, including Zika, Chikungunya, Dengue and Yellow Fever viruses. Issues such as historical overview, pathogenesis, transmission, clinical conditions, diagnosis, treatment and prevention are addressed.

High estimated prevalence of asymptomatic dengue viremia in blood donors during a dengue epidemic in southern Taiwan, 2015

BACKGROUND

Southern Taiwan experienced a severe dengue epidemic in 2015. Adult asymptomatic cases would raise concerns on transfusion-transmitted dengue virus (DENV) infection. The aim of this study was to evaluate the magnitude of such a risk in Tainan City during this epidemic.

STUDY DESIGN AND METHODS

The daily prevalence of asymptomatic dengue viremia in blood donors in Tainan City and in selected high-incidence districts during the 2015 dengue epidemic was estimated by an established mathematical model. Duration of viremia, duration of viremia before symptom onset, apparent-to-inapparent infection ratio, and reporting-to-underreporting ratio were four main parameters used in the model.

RESULTS

The estimated maximal and mean daily prevalence of asymptomatic dengue viremia in blood donors in Tainan during this dengue epidemic was 74.4 (95% confidence interval [CI], 60.8-88.0) and 15.0 (95% CI, 12.3-17.7) per 10,000, respectively. In the district with the highest incidence, the maximal and mean daily prevalence of asymptomatic viremia was 328.8 (95% CI, 271.1-386.2) and 55.3 (95% CI, 43.4-63.3) per 10,000, respectively. Approximately 234 (95% CI, 191-276) blood components containing DENV were produced during the epidemic.

CONCLUSION

Although dengue is currently not endemic in Taiwan, physicians need to be aware of the risk of transfusion-transmitted DENV infection. Our results suggest that screening measures to ensure blood safety should be evaluated and implemented during dengue epidemics even in nonendemic areas. Timely estimation of daily asymptomatic viremia prevalence by districts can help to select high-risk areas for such measures and to evaluate cost-effectiveness.

Emerging Infectious Diseases and Blood Safety: Modeling the Transfusion-Transmission Risk

While the transfusion-transmission (TT) risk associated with the major transfusion-relevant viruses such as HIV is now very low, during the last 20 years there has been a growing awareness of the threat to blood safety from emerging infectious diseases, a number of which are known to be, or are potentially, transfusion transmissible. Two published models for estimating the transfusion-transmission risk from EIDs, referred to as the Biggerstaff-Petersen model and the European Upfront Risk Assessment Tool (EUFRAT), respectively, have been applied to several EIDs in outbreak situations. We describe and compare the methodological principles of both models, highlighting their similarities and differences. We also discuss the appropriateness of comparing results from the two models. Quantitating the TT risk of EIDs can inform decisions about risk mitigation strategies and their cost-effectiveness. Finally, we present a qualitative risk assessment for Zika virus (ZIKV), an EID agent that has caused several outbreaks since 2007. In the latest and largest ever outbreak, several probable cases of transfusion-transmission ZIKV have been reported, indicating that it is transfusion-transmissible and therefore a risk to blood safety. We discuss why quantitative modeling the TT risk of ZIKV is currently problematic.

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During the last 20 years there has been a growing awareness of the threat to blood safety from emerging infectious diseases (EIDs), a number of which are known to be, or are potentially, transfusion-transmissible.

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The transfusion-transmission risk of EID agents can be estimated by risk modeling which can form an important part of risk assessments and inform decisions regarding risk mitigation strategies.

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We describe and compare the methodological principles of two published risk models for estimating the transfusion transmission risk of EIDs.

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We use Zika virus as a case study to demonstrate that reliable risk modeling for EID agents can be problematic due to the uncertainty of the input parameters.

Zika and chikungunya virus infections in hematopoietic stem cell transplant recipients and oncohematological patients

Aedes mosquitoes are well adapted in domestic environments and widespread in tropical regions. Since 2015, Brazil has been experiencing a triple epidemic of dengue (DENV), chikungunya (CHKV), and Zika (ZIKV) viruses. The last 2 viruses are likely following the path of DENV, which has been endemic in most parts of the country since the 1980s. Given this triple epidemic, we proposed a prospective and collaborative study to assess the prevalence, morbidity, and mortality of DENV, CHKV, and ZIKV infections in hematopoietic stem cell transplant (HSCT) recipients and oncohematological patients. A case definition strategy (fever and rash) was used to prompt diagnostic investigation of DENV, ZIKV, and CHKV, which was accomplished by real-time polymerase chain reaction with plasma and urine samples. Clinical follow-up was performed 7 and 30 days after symptom onset. We report here the first cases of ZIKV and CHKV infections diagnosed in this ongoing study. From February to May 2016, 9 of the 26 patients (34.6%) fulfilling case definition criteria were diagnosed with DENV (3 cases), ZIKV (4 cases), or CHKV (2 cases) infections. Prolonged viremia and viruria were observed in dengue and Zika fever cases, respectively. Thrombocytopenia was the most frequent complication. Delayed engraftment was noted in 1 patient who acquired ZIKV 25 days before HSCT. All patients survived without sequelae. With the geographic expansion of arboviruses, donor and recipient screening may become mandatory. Patients living in areas where these viruses are not endemic are also at risk, since these viruses can be transmitted by blood as well as organ or tissue transplantation.

The Impact of Emerging Infectious Diseases on Chinese Blood Safety

Emerging infectious diseases (EIDs) have always been one of the major threats to public health. Although the implementation of mandatory testing for 4 classical transfusion-transmitted infectious-human immunodeficiency virus, hepatitis B virus, hepatitis C virus, and syphilis-has reduced the transfusion risk of these pathogens, the potential threat of various EID agents and their constantly evolving variants to blood safety in China is not fully understood. This review presents 9 representative EID agents that are autochthonous and epidemic nationally or regionally in China. The epidemiologic status and distribution of these EID agents among donors and/or healthy populations are summarized. The potential risks of these EID agents to blood safety are discussed. The review also explores strategies to strengthen hemovigilance systems and studies to further evaluate the impact of EID agents on blood safety.

Seroprevalence of Asymptomatic Dengue Virus Infection and Its Antibodies Among Healthy/Eligible Saudi Blood Donors: Findings From Holy Makkah City

BACKGROUND

Threat to blood transfusion-transmitted dengue virus (DENV) and its antibodies has recently emerged worldwide. Dengue fever is an endemic disease in Saudi Arabia, particularly in its Western region. The aim of this study was to estimate the seroprevalence of asymptomatic DENV infection and its antibodies among eligible Saudi blood donors.

METHODS

Serum samples from 910 healthy/eligible adult male Saudi blood donors, who reside in Holy Makkah City of Saudi Arabia, were collected between March 2015 and August 2016 and screened for the detection of DENV nonstructural protein 1 (NS1) antigen and anti-DENV IgM and IgG antibodies using commercial enzyme-linked immunosorbent assay kits (Panbio, Brisbane, QLD, Australia).

RESULTS

Among the tested donors, 48 (5.3%) were seropositive for DENV-NS1 antigen, whereas 50 (5.5%) and 354 (38.9%) were seropositive for anti-DENV IgM and IgG antibodies, respectively. Seropositivity for DENV-NS1 antigen and/or anti-DENV IgM antibody among the tested donors reflects their ongoing asymptomatic viremic infectious stage with DENV during their donation time, whereas high prevalence of anti-DENV IgG seropositivity reflects the high endemicity of dengue disease in this region of Saudi Arabia.

CONCLUSIONS

These results show high prevalence of asymptomatic DENV infection and its antibodies among Saudi blood donors, raising the importance of establishing blood screening for dengue disease at different blood donation services and units in Saudi Arabia to improve the guarantee of blood transfusions and to control DENV dissemination.

Mitigating the Risk of Transfusion-Transmitted Dengue in Australia

Dengue viruses (DENV 1–4) are a risk to transfusion safety, with several transfusion-transmitted (TT) cases reported globally. DENV 1–4 are endemic in over 100 countries, with seasonal outbreaks occurring in northeastern Australia. To mitigate TT-DENV risk in Australia, fresh blood components are not manufactured from donors returning from any area (domestic/overseas) with known dengue transmission. Alternatively, TT-DENV risk may be mitigated using an appropriate blood donor screening assay. We aimed to determine the rate of dengue infection in donors during dengue outbreaks in Australia. Plasma samples were collected from blood donors during local dengue outbreaks. All samples were tested for the presence of DENV RNA and selected samples were tested for DENV antigen (nonstructural protein 1, NS1) with two assays. No donors residing in high risk areas had detectable levels of DENV RNA or NS1 and no cases of DENV viremia were detected in blood donors residing in areas of Australia experiencing DENV outbreaks. Definitive conclusions could not be drawn from this study; however, the lack of detection of DENV RNA or antigen in donations suggests that the current risk of TT-DENV is low and maintaining the fresh component restriction for “at-risk” donors is appropriate.

Transfusion transmitted dengue: One donor infects two patients

Dengue virus can be transmitted via blood transfusion. We report an interesting case where two surgical patients developed possible transfusion transmitted dengue when transfused blood components of the same donor. Dengue remains a threat to blood supply especially in endemic region.

Zika and the Blood Supply: A Work in Progress

Zika virus can be transmitted by transfusion, but the harm caused to recipients is not clear in most cases. It is very likely that the virus could also be transmitted by transplanted organs. Sensitivity to the risk from transfusion is elevated by consideration of possible severe neurologic damage in fetuses. Strategies for dealing with transfusion risk vary with the presence of Zika in the region. In nonendemic areas, risks can be reduced by excluding donors who have exposure through travel or sexual contact with someone at risk. In both endemic and nonendemic areas, the risk can be further reduced by nucleic acid testing of donors, or pathogen reduction of platelet and plasma products. The real risk to the population depends on the frequency of infection as well as the efficacy of these interventions. The interventions chosen will depend on the risk assessment for any situation; in the United States at this time, a combination of travel deferrals, testing, and, to a lesser extent, pathogen reduction is being used, but universal testing of US blood donors under investigational use has been mandated by the US Food and Drug Administration, beginning with states most at risk of local transmission. Canada is largely using travel deferrals. A precautionary approach may be taken; however, a formal decision-making framework has been suggested. The situation globally is clearly very fluid, as the epidemic continues to spread and we continue to learn how to best protect recipients of blood and transplants.

Development of a novel dengue virus serotype-specific multiplex real-time reverse transcription-polymerase chain reaction assay for blood screening

BACKGROUND

Dengue fever is caused by four related RNA viruses of the genus Flavivirus, dengue virus (DENV)-1, -2, -3, and -4, which are transmitted to humans by mosquitoes. Although DENV is not endemic in Japan, an autochthonous dengue outbreak occurred in 2014. Several transfusion-transmitted cases have also been reported after the use of blood and plasma products in DENV-endemic countries. The aim of this study was to develop a novel multiplex reverse transcription-polymerase chain reaction (RT-PCR) assay for DENV blood screening.

STUDY DESIGN AND METHODS

Large-scale oligonucleotide screening was performed to obtain DENV-specific primers and probes using a variety of DENV clinical isolates. A multiplex RT-PCR assay was then developed using the identified oligonucleotides and the ability of this assay to detect DENV RNA was evaluated.

RESULTS

A number of oligonucleotides suitable for DENV RNA detection were identified and a novel DENV serotype-specific multiplex RT-PCR assay was successfully established. Comparative analysis revealed that the multiplex assay could detect levels of viral contamination as low as 100 viral copies/mL.

CONCLUSION

This established serotype-specific multiplex RT-PCR assay provides a simple, sensitive, and quantitative detection method for DENV, which could be applied in the screening of blood samples to prevent transfusion-transmitted DENV infection.

Update on non-vector transmission of dengue: relevant studies with Zika and other flaviviruses

Human dengue virus infection without mosquito vector has been reported to occur as a result of mucocutaneous transmission, needlestick in patient care and laboratory accident, blood transfusion, bone marrow transplant, organ transplant, intrapartum and perinatal transmission, and breastfeeding. The emergence of Zika virus, another mosquito-borne flavivirus, has illustrated additional potential routes of non-vector transmission in humans. A recent study in another flavivirus, Japanese encephalitis virus, in pigs has also demonstrated non-vector transmission. We highlight some reports on dengue virus that have documented non-vector transmission and that are relevant to the transmission of Zika virus and other flaviviruses.

Zika Virus and the Blood Supply: What Do We Know?

Zika virus (ZIKV), a mosquito-borne Flavivirus and emerging infectious disease, is the focus of an international public health emergency after its rapid spread through the Americas and the Caribbean. Although most ZIKV infections are subclinical or characterized by mild febrile illness, ZIKV has been implicated in severe complications, most notably microcephaly in babies born to incident infected mothers during pregnancy. As yet, the extent to which ZIKV is transfusion transmissible remains undefined. Nonetheless, a high prevalence of asymptomatic infection during outbreaks, the demonstration of ZIKV in blood donors, and 4 possible cases of transfusion-transmitted ZIKV in Brazil have raised concern for risk to the blood supply. Consequently, a proactive response is underway by blood collection agencies, regulatory bodies, national funding agencies, and industry alike. Mitigation strategies differ between endemic and nonendemic areas. In the continental United States, the American Association of Blood Banks and Food and Drug Administration guidelines recommend travel-based deferral for those returning from affected areas, and nucleic acid testing is being initiated under an investigational new drug application in Puerto Rico and selected areas of the United States. Options are less clear for countries where autochthonous vector-borne transmission is active. The burden of Zika falls in low-resource countries where high cost and technical barriers associated with testing and pathogen reduction pose barriers to implementation. Additional strategies include maintaining selective inventory for high-risk recipients (eg, pregnant women). We review the available data as of July 2016 on ZIKV in relation to the blood supply including risk, mitigation strategies, and barriers to implementation in addition to the research that is needed to address current uncertainty.

Dengue and chikungunya viruses in plasma are effectively inactivated after treatment with methylene blue and visible light

BACKGROUND

Arboviruses, such as dengue viruses (DENV) and chikungunya virus (CHIKV), pose a risk to the safe transfusion of blood components, including plasma. Pathogen inactivation is an approach to manage this transfusion transmission risk, with a number of techniques being used worldwide for the treatment of plasma. In this study, the efficacy of the THERAFLEX MB-Plasma system to inactivate all DENV serotypes (DENV-1, DENV-2, DENV-3, DENV-4) or CHIKV in plasma, using methylene blue and light illumination at 630 nm, was investigated.

STUDY DESIGN AND METHODS

Pooled plasma units were spiked with DENV-1, DENV-2, DENV-3 DENV-4, or CHIKV and treated with the THERAFLEX MB-Plasma system at four light illumination doses: 20, 40, 60, and 120 (standard dose) J/cm(2) . Pre- and posttreatment samples were collected and viral infectivity was determined. The reduction in viral infectivity was calculated for each dose.

RESULTS

Treatment of plasma with the THERAFLEX MB-Plasma system resulted in at least a 4.46-log reduction in all DENV serotypes and CHIKV infectious virus. The residual infectivity for each was at the detection limit of the assay used at 60 J/cm(2) , with dose dependency also observed.

CONCLUSIONS

Our study demonstrated the THERAFLEX MB-Plasma system can reduce the infectivity of all DENV serotypes and CHIKV spiked into plasma to the detection limit of the assay used at half of the standard illumination dose. This suggests this system has the capacity to be an effective option for managing the risk of DENV or CHIKV transfusion transmission in plasma.

Riboflavin and ultraviolet light: impact on dengue virus infectivity

BACKGROUND

Dengue viruses (DENV 1-4) are emerging across the world, and these viruses pose a risk to transfusion safety. Pathogen inactivation may be an alternative approach for managing the risk of DENV transfusion transmission. This study aimed to investigate the ability of riboflavin and UV light to inactivate DENV 1-4 in platelet concentrates.

MATERIALS AND METHODS

DENV 1-4 were spiked into buffy coat-derived platelet concentrates in additive solution (SSP+) before being treated with riboflavin and UV light. Infectious virus was quantified pre- and posttreatment, and the reduction in viral infectivity was calculated.

RESULTS

All four DENV serotypes were modestly reduced after treatment. The greatest amount of reduction in infectivity was observed for DENV-4 (1·81 log reduction) followed by DENV-3 (1·71 log reduction), DENV-2 (1·45 log reduction) and then DENV-1 (1·28 log reduction).

CONCLUSION

Our study demonstrates that DENV 1-4 titres are modestly reduced following treatment with riboflavin and UV light. With the increasing number of transfusion-transmitted cases of DENV around the globe, and the increasing incidence and geographical distribution of DENV, additional approaches for maintaining blood safety may be required in the future.

Duration of Dengue Viremia in Blood Donors and Relationships Between Donor Viremia, Infection Incidence and Clinical Case Reports During a Large Epidemic

BACKGROUND

Dengue viruses (DENV-1-4) pose a transfusion-transmission risk. This study estimated the dengue RNA detection period in asymptomatic blood donors and relationships between donor viremia and dengue incidence during a large epidemic.

METHODS

Donor samples from the 2012 dengue transmission season in Rio de Janeiro, Brazil, were tested for DENV RNA by a transcription-mediated amplification (TMA) assay, with DENV types and viral loads determined by polymerase chain reaction. Samples collected during the first and last weeks of enrollment were tested for DENV immunoglobulin (Ig) G and IgM to estimate incidence during the study period, which was analyzed relative to nucleic acid amplification technology (NAT) yield to estimate the duration of NAT-detectable viremia and compared with reported clinical dengue cases in Rio.

RESULTS

Samples from 16 241 donations were tested; 87 (0.54%) were confirmed as DENV-4 RNA positive. Dengue IgM-positive/IgG-positive reactivity increased from 2.8% to 8.8%, indicating a 6.2% incidence (95% confidence interval [CI], 3.2%-9.1%) during the study period. Based on these data, we estimated a 9.1-day period (95% CI, 4.4-13.9 days) of RNA detectable with TMA. With 100 475 reported cases of clinical dengue, 1 RNA-positive donation was identified per 800 DENV cases.

CONCLUSIONS

These parameters allow projections of dengue incidence from donor NAT yield data and vice versa, and suggest that viremic donations will be rare relative to clinical disease cases.

Inactivation of dengue, chikungunya, and Ross River viruses in platelet concentrates after treatment with ultraviolet C light

BACKGROUND

Arboviruses, including dengue (DENV 1-4), chikungunya (CHIKV), and Ross River (RRV), are emerging viruses that are a risk for transfusion safety globally. An approach for managing this risk is pathogen inactivation, such as the THERAFLEX UV-Platelets system. We investigated the ability of this system to inactivate the above mentioned arboviruses.

STUDY DESIGN AND METHODS

DENV 1-4, CHIKV, or RRV were spiked into buffy coat (BC)-derived platelet (PLT) concentrates in additive solution and treated with the THERAFLEX UV-Platelets system at the following doses: 0.05, 0.1, 0.15, and 0.2 J/cm(2) (standard dose). Pre- and posttreatment samples were taken for each dose, and the level of viral infectivity was determined.

RESULTS

At the standard ultraviolet C (UVC) dose (0.2 J/cm(2) ), viral inactivation of at least 4.43, 6.34, and 5.13 log or more, was observed for DENV 1-4, CHIKV, and RRV, respectively. A dose dependency in viral inactivation was observed with increasing UVC doses.

CONCLUSIONS

Our study has shown that DENV, CHIKV, and RRV, spiked into BC-derived PLT concentrates, were inactivated by the THERAFLEX UV-Platelets system to the limit of detection of our assay, suggesting that this system could contribute to the safety of PLT concentrates with respect to these emerging arboviruses.

Estimating the risk of dengue transmission from Dutch blood donors travelling to Suriname and the Dutch Caribbean

BACKGROUND

The risk of dengue transmitted by travellers is known. Methods to estimate the transmission by transfusion (TT) risk from blood donors travelling to risk areas are available, for instance, the European Up-Front Risk Assessment Tool (EUFRAT). This study aimed to validate the estimated risk from travelling donors obtained from EUFRAT.

METHODS

Surveillance data on notified dengue cases in Suriname and the Dutch Caribbean islands (Aruba, Curaçao, St. Maarten, Bonaire, St. Eustatius and Saba) in 2001-2011 was used to calculate local incidence rates. Information on travel and donation behaviour of Dutch donors was collected. With the EUFRAT model, the TT risks from Dutch travelling donors were calculated. Model estimates were compared with the number of infections in Dutch travellers found by laboratory tests in the Netherlands.

RESULTS

The expected cumulative number of donors becoming infected during travels to Suriname and the Dutch Caribbean from 2001 to 2011 was estimated at 5 (95% CI, 2-11) and 86 (45-179), respectively. The infection risk inferred from the laboratory-based study was 19 (9-61) and 28 (14-92). Given the independence of the data sources, these estimates are remarkably close. The model estimated that 0·02 (0·001-0·06) and 0·40 (0·01-1·4) recipients would have been infected by these travelling donors.

CONCLUSIONS

The EUFRAT model provided an estimate close to actual observed number of dengue infections. The dengue TT risk among Dutch travelling donors can be estimated using basic transmission, travel and donation information. The TT risk from Dutch donors travelling to Suriname and the Dutch Caribbean is small.