Evidence of meaningful levels ofTrypanosoma cruziin platelet concentrates from seropositive blood donors

Chagas Disease

Chagas disease, which is caused by infection with the parasite Trypanosoma cruzi, is a leading neglected tropical disease in the United States. An estimated 240 000 to 350 000 persons in the United States are infected, primarily immigrants from Mexico, Central America, and South America, where the disease is endemic. The parasite is transmitted by the triatomine bug but can also be passed through blood transfusion, via organ transplant, or congenitally. Approximately 30% of infected persons later develop cardiac and/or gastrointestinal complications. Health care providers should consider screening at-risk patients with serologic testing. Early diagnosis and treatment with benznidazole or nifurtimox can help prevent complications.

Chronic Chagas Disease-the Potential Role of Reinfections in Cardiomyopathy Pathogenesis

PURPOSE OF THE REVIEW

Chagas disease is a neglected anthropozoonosis of global importance with significant cardiovascular-associated mortality. This review focuses on the Trypanosoma cruzi reinfections' role in chronic Chagas cardiomyopathy pathogenesis. We discuss and summarize the available data related to pathology, pathogenesis, diagnosis, and treatment of reinfections.

RECENT FINDINGS

Reinfections influence the genetic and regional diversity of T. cruzi, tissue tropism, modulation of the host's immune system response, clinical manifestations, the risk for congenital infections, differences in diagnostics performances, response to antiparasitic therapy, and the natural history of the disease. Animal models suggest that reinfections lead to worse outcomes and increased mortality, while other studies showed an association between reinfections and lower parasitemia levels and subsequent infection protection. In some regions, the human risk of reinfections is 14% at 5 years. Evidence has shown that higher anti-T. cruzi antibodies are correlated with an increased rate of cardiomyopathy and death, suggesting that a higher parasite exposure related to reinfections may lead to worse outcomes. Based on the existing literature, reinfections may play a role in developing and exacerbating chronic Chagas cardiomyopathy and are linked to worse outcomes. Control efforts should be redirected to interventions that address structural poverty for the successful and sustainable prevention of Chagas disease.

Automatic detection of the parasite Trypanosoma cruzi in blood smears using a machine learning approach applied to mobile phone images

Chagas disease is a life-threatening illness caused by the parasite Trypanosoma cruzi. The diagnosis of the acute form of the disease is performed by trained microscopists who detect parasites in blood smear samples. Since this method requires a dedicated high-resolution camera system attached to the microscope, the diagnostic method is more expensive and often prohibitive for low-income settings. Here, we present a machine learning approach based on a random forest (RF) algorithm for the detection and counting of T. cruzi trypomastigotes in mobile phone images. We analyzed micrographs of blood smear samples that were acquired using a mobile device camera capable of capturing images in a resolution of 12 megapixels. We extracted a set of features that describe morphometric parameters (geometry and curvature), as well as color, and texture measurements of 1,314 parasites. The features were divided into train and test sets (4:1) and classified using the RF algorithm. The values of precision, sensitivity, and area under the receiver operating characteristic (ROC) curve of the proposed method were 87.6%, 90.5%, and 0.942, respectively. Automating image analysis acquired with a mobile device is a viable alternative for reducing costs and gaining efficiency in the use of the optical microscope.

Parasitic Load Correlates With Left Ventricular Dysfunction in Patients With Chronic Chagas Cardiomyopathy

Background: Chronic Chagas disease (CChD), one of the infectious parasitic diseases with the greatest social and economic impact upon a large part of the American continent, has distinct clinical manifestations in humans (cardiac, digestive, or mixed clinical forms). The mechanisms underlying the development of the most common and ominous clinical form, the chronic Chagas cardiomyopathy (CCC) have not been completely elucidated, despite the fact that a high intensity of parasite persistence in the myocardium is deemed responsible for an untoward evolution of the disease. The present study aimed to assess the parasite load CCC and its relation to left ventricular ejection fraction (LVEF), a definite prognostic marker in patients with CCC.

Methods: Patients with CCC were clinically evaluated using 12-lead-electrocardiogram, echocardiogram, chest X-ray. Peripheral blood sampling (5 ml of venous blood in guanidine/EDTA) was collected from each patient for subsequent DNA extraction and the quantification of the parasite load using real-time PCR.

Results: One-hundred and eighty-one patients with CCC were evaluated. A total of 140 (77.3%) had preserved left ventricular ejection fraction (of ≥40%), and 41 individuals had LV dysfunction (LVEF of <40%). A wide variation in parasite load was observed with a, mean of 1.3460 ± 2.0593 (0.01 to 12.3830) par. Eq./mL. The mean ± SD of the parasite load was 0.6768 ± 0.9874 par. Eq./mL and 3.6312 ± 2.9414 par. Eq./mL in the patients with LVEF ≥ 40% and <40%, respectively.

Conclusion: The blood parasite load is highly variable and seems to be directly related to the reduction of LVEF, an important prognostic factor in CCC patients.

Haemostatic function measured by thromboelastography and metabolic activity of platelets treated with riboflavin and UV light

BACKGROUND

Pathogen reduction technology (PRT) may damage platelet (PLT) components. To study this, metabolic activity and haemostatic function of buffy coat (BC) PLT concentrates, with or without riboflavin and UV light PRT treatment, were compared.

MATERIAL AND METHODS

Twenty-four BC PLT concentrates, leukoreduced and diluted in additive solution, were grouped into 12 type-matched pairs, which were pooled and divided into 12 non-PRT-treated BC PLT concentrates (control units) and 12 riboflavin and UV PRT-treated BC PLT concentrates (test units). Haemostatic function and metabolic parameters were monitored by thrombelastography at days 1, 3, 7 and 14 post collection in both PLT groups.

RESULTS

Loss of PLT discoid shape, glucose consumption, lactate production, and decrease in pH were greater in the PRT-treated PLTs than in control PLTs over time (p<0.001). PLT haemostatic function evaluated by clot strength was also significantly weaker in PRT-treated PLTs compared with the excellent clot quality of control PLTs at day 7 (maximum amplitude: 41.27 vs 64.27; p<0.001), and even at day 14 (21.16 vs 60.39; p<0.001) of storage.

DISCUSSION

Pathogen reduction technology treatment accelerates and increases platelet storage lesion, resulting in glucose depletion, lactate accumulation, PLT acidification, and discoid shape loss. The clots produced by control PLTs at day 14 were still remarkably strong, whereas at day 7 PRT-treated PLTs produced weaker clots compared to the control group. Clinical trials investigating the efficacy of PRT-treated PLTs transfused at the end of the storage period (day 7), when the in vitro clot strength is weaker, are needed.

Chagas cardiomyopathy and heart failure: From epidemiology to treatment

Chagas disease is among the neglected tropical diseases recognized by the World Health Organization that have received insufficient attention from governments and health agencies. Chagas disease is endemic in 21 Latin America regions. Due to globalization and increased migration, it has crossed borders and reached other regions including North America and Europe. The clinical presentation of the disease is highly variable, from general symptoms to severe cardiac involvement that can culminate in heart failure. Chagas heart disease is multifactorial, and can include dilated cardiomyopathy, thromboembolic phenomena, and arrhythmias that may lead to sudden death. Diagnosis is by methods such as enzyme-linked immunosorbent assay (ELISA) and the degree of cardiac involvement should be investigated with complementary exams including ECG, chest radiography and electrophysiological study. There have been insufficient studies on which to base specific treatment for heart failure due to Chagas disease. Treatment should therefore be derived from guidelines for heart failure that are not specific for this disease. Heart transplantation is a viable option with satisfactory success rates that has improved survival.

Quantification of parasite burden of Trypanosoma cruzi and identification of Discrete Typing Units (DTUs) in blood samples of Latin American immigrants residing in Barcelona, Spain

BACKGROUND

Trypanosoma cruzi has a high genetic and biological diversity and has been subdivided into seven genetic lineages, named TcI-TcVI and TcBat. DTUs TcI-TcII-TcV and TcVI are agents of ChD in different regions of Latin America. Due to population movements, the disease is an emergent global public health problem. Thus, the aim of this study was to quantify the parasitic load and identify the presence of T. cruzi DTUs in 101 Latin American immigrants with chronic ChD, residing in Barcelona, Spain.

METHODOLOGY / PRINCIPAL FINDINGS

5ml of peripheral blood were collected in guanidine/EDTA from each patient for DNA extraction, quantification of the parasitic load and genotyping. A great variation of the parasitic load of the patients was verified: from 0.001 to 22.2 T. cruzi DNA (fg) / Blood DNA (ng). In patients from Bolivia the parasitic load was 3.76±4.43 T. cruzi DNA (fg) / Blood DNA (ng) (mean ± SD), in patients of other countries was 0.95±1.38 T. cruzi DNA (fg) / Blood DNA (ng). No statistically significant difference was observed in the parasitic load between patients with the indeterminate and cardiac forms of ChD (p = 0,57). Parasite genotyping was performed by multilocus conventional PCR. In patients from Bolivia there was a nearly equal prevalence of DTUs TcV (27/77), TcII/TcV/TcVI (26/77), and TcII/TcVI (22/77). TcVI was detected in only 2 samples (2/77). A higher prevalence of TcII/TcVI (19/24) was verified in patients of other countries, with low prevalence of TcII/TcV/TcVI (4/24) and TcV (1/24).

CONCLUSIONS/SIGNIFICANCE

In this study, low/medium parasitic load was found in all patients evaluated. Our data corroborate previous conclusions indicating that patients from the Bolivia, living in Spain, are predominantly infected by TcV, and TcVI DTUs. On the other hand, in Non-Bolivians patients TcII/TcVI predominated. Surprisingly, in our cohort of 101 patients no infection by TcI DTU was observed.

Screening for Trypanosoma cruzi infection in immigrants and refugees: Systematic review and recommendations from the Spanish Society of Infectious Diseases and Clinical Microbiology

BackgroundChagas disease has spread beyond its original borders on the American continent with migration. It can be transmitted from mother to child, through organ transplantation and transfusion of blood and blood products. It is necessary to determine when to screen for this infection.AimOur objective was to evaluate the appropriateness of screening for Trypanosoma cruzi infection in Latin American migrants and their descendants.MethodsWe reviewed the literature using rigorous criteria. The quality of evidence was ranked according to the GRADE classification. An evidence to decision framework was adopted to provide information on the most relevant aspects necessary to formulate recommendations.ResultsThe 33 studies evaluated revealed a prevalence of T. cruzi infection among Latin American migrants in Europe of 6.08% (95% confidence interval (CI): 3.24-9.69; 28 studies). Vertical transmission occurred in three of 100 live births (95% CI: 1-6; 13 studies). The prevalence of cardiovascular disease was 19% (95% CI: 13-27; nine studies), including only 1% severe cardiac events (95% CI: 0-2; 11 studies). The overall quality of evidence was low because of risk of bias in the studies and considerable heterogeneity of the evaluated populations. The recommendations took into account economic studies on the value of screening strategies and studies on acceptability of screening and knowledge of the disease in the affected population.ConclusionsWe identified five situations in which screening for T. cruzi infection is indicated. We recommend screening persons from endemic areas and children of mothers from these areas.

Blood Transfusion-Associated Infections in the Twenty-First Century: New Challenges

Blood transfusions are vital components of modern medical treatment to which there is no viable alternative despite efforts to create artificial blood. Each year thousands of lives are saved by blood transfusions in every country of the world. However, blood and blood products can result in significant adverse events including immunologic reactions, infections, inefficacy, and others which can sometimes result in death and severe disability. Thus, the sustainability of safe blood systems and costs are considered to be at crisis level. In industrialized countries, the risk of transfusion-transmitted infections such as HIV, syphilis, hepatitis viruses B and C are very low [generally [<1 in a million units], but in developing countries [especially in Africa] blood safety is still not assured. Compounding the problem of blood/product safety with respect to infectious agents are new emerging infectious microbes that are not being routinely tested for in blood that are donated. This chapter reviews the infectious risk of blood transfusions, types, mode and geographic variation, and the methods being used by blood services to attenuate and prevent these risks.

Who do we gain? Enhancement of blood supplies by additional testing for donors who travel

AIMS/OBJECTIVES

To describe the impact of additional testing on the England blood supply.

BACKGROUND

The blood service for England, NHS Blood and Transplant, applies a system of deferral and testing to donors with potential exposure to Chagas disease, malaria and West Nile virus; however, testing costs must be justified. Here, we describe the donations and donors gained by testing.

METHODS

Donation testing results and demographic data on donors in England where additional testing was applied were analysed in 2012-2016. The total number and proportion of donations tested, reactive and confirmed positive were calculated. Proportions of donors requiring additional tests were calculated by ethnic group for first-time and repeat donors.

RESULTS

Additional testing for travel was applied to 3·5% of NHSBT blood donations between 2012 and 2016. Over 98% of these tests were non-reactive. Only malaria tests were confirmed positive, in 1·7% of donations tested. In first-time donors, 45 and 40% of Asian and Black donors required an additional test, respectively, mainly for malaria. Testing for West Nile virus increased from 1·5% in 2012 to 2·2% of donations in 2016.

CONCLUSION

The majority of additional tests were screened negative, allowing approximately 64 000 donations to be released for issue annually. Donors most affected by malaria testing were more likely to have rare blood groups and be targeted for recruitment, whereas those given West Nile virus testing were mainly regular donors required for continuity of supply. These data show differences in the characteristics of donors by test and can be used to inform decisions about additional testing and deferrals.

Seroprevalence of Trypanosoma cruzi infection among at-risk blood donors in Japan

BACKGROUND

Chagas disease is caused by Trypanosoma cruzi and is endemic in Latin America. In nonendemic countries, including Japan, Chagas disease is primarily a problem in the context of transfusion transmission. Approximately 250,000 immigrants from Latin America reside in Japan, and many of those individuals serve as active blood donors. This study surveyed the seroprevalence of T. cruzi infection among at-risk blood donors in Japan, defined as those who themselves (or whose mothers) were born (or raised) in Latin America, or those with a travel history to Latin America.

STUDY DESIGN AND METHODS

Blood samples were obtained from at-risk donors in two periods, 2004-2012 and 2013-2016. Collected samples were tested for T. cruzi antibodies using both an enzyme-linked immunosorbent assay and a chemiluminescent immunoassay. Samples that tested positive in both assays were additionally tested by polymerase chain reaction, and look-back investigation was conducted when necessary.

RESULTS

Of 18,484 samples obtained from 18,076 at-risk donors, 3 (1:6,025, 0.017%) donors showed seroreactivity by enzyme-linked immunosorbent assay and chemiluminescent immunoassay. All antibody-positive donors were born in Latin America. One of them also was positive for T. cruzi DNA. Eleven previous donations from this donor were subjected to look-back investigation, and five recipients were tested. All five recipients tested negative for T. cruzi antibodies.

CONCLUSION

Seroprevalence of T. cruzi was 0.017% among at-risk donors in Japan. Transfusion-transmitted infection of Chagas disease has not been confirmed to date. Screening for T. cruzi antibodies by targeting at-risk donors is an appropriate strategy for ensuring blood safety in Japan.

Chagas disease

Chagas disease is an anthropozoonosis from the American continent that has spread from its original boundaries through migration. It is caused by the protozoan Trypanosoma cruzi, which was identified in the first decade of the 20th century. Once acute infection resolves, patients can develop chronic disease, which in up to 30-40% of cases is characterised by cardiomyopathy, arrhythmias, megaviscera, and, more rarely, polyneuropathy and stroke. Even after more than a century, many challenges remain unresolved, since epidemiological control and diagnostic, therapeutic, and prognostic methods must be improved. In particular, the efficacy and tolerability profile of therapeutic agents is far from ideal. Furthermore, the population affected is older and more complex (eg, immunosuppressed patients and patients with cancer). Nevertheless, in recent years, our knowledge of Chagas disease has expanded, and the international networking needed to change the course of this deadly disease during the 21st century has begun.

Chagas disease in Europe: A review for the internist in the globalized world

Chagas disease (CD) or American trypanosomiasis identified in 1909 by Carlos Chagas, has become over the last 40years a global health concern due to the huge migration flows from Latin America to Europe, United States, Canada and Japan. In Europe, most migrants from CD-endemic areas are concentrated in Spain, Italy, France, United Kingdom and Switzerland. Pooled seroprevalence studies conducted in Europe show an overall 4.2% prevalence, with the highest infection rates observed among individuals from Bolivia (18.1%). However, in most European countries the disease is neglected with absence of screening programmes and low access to diagnosis and treatment. Physicians working in Europe should also be aware of the risk of autochthonous transmission of Trypanosoma cruzi to newborns by their infected mothers and to recipients of blood or transplanted organs from infected donors. Finally, physicians should be able to recognize and treat the most frequent and serious complications of chronic Chagas disease, namely cardiomyopathy, megacolon and megaesophagus. This review aims to highlights the problem of CD in Europe by reviewing papers published by European researchers on this argument, in order to raise the awareness of internists who are bound to increasingly encounter patients with the disease in their routine daily activities.

Frequency of Trypanosoma cruzi parasitemia among infected blood donors with a potential association between parasite lineage and transfusion transmission

BACKGROUND

Trypanosoma cruzi is endemic to the Americas where it demonstrates multiple lineages over a vast geographic range (i.e., United States to Argentina). These lineages possess divergent geographic and biologic characteristics, including variations in disease manifestations. Herein, we report the frequency of parasitemia among seropositive US blood donors and the potential association between parasite lineage and transfusion transmission.

STUDY DESIGN AND METHODS

Blood donors identified as T. cruzi seropositive during screening were enrolled in follow-up studies, including hemoculture testing and a risk factor questionnaire. Positive hemocultures were expanded to obtain sufficient parasites for molecular lineage determination and analysis. Country of birth, obtained from the questionnaire, was used to predict parasite lineage in the absence of demonstrable parasitemia for infected donors.

RESULTS

Eighteen (6.8%) of 263 seropositive donors were hemoculture positive. Among the 17 hemocultures expanded for lineage determination, TcV was identified more frequently (n = 12), compared to TcI (n = 2), TcII (n = 1), and TcVI (n = 2). When presumptive parasite lineages were compared to hemoculture results, only two of 157 (1.3%) TcI versus 13 of 38 (34.2%) TcII/TcV/TcVI non-US donors were parasitemic; three of 44 (6.8%) US donors were TcV or TcVI.

CONCLUSIONS

Based on lineage determination for donors with parasitemia; hemoculture positivity associated with presumptive parasite lineage; and implicated donors from US, Canadian, and Spanish transfusion cases, donors from Southern South America are significantly more likely to have parasitemia and transmit infection to blood recipients (TcII, TcV, or TcVI vs. TcI). Thus, parasite lineage may be associated with risk of transfusion-transmitted T. cruzi.

Detection and Quantification of Viable and Nonviable Trypanosoma cruzi Parasites by a Propidium Monoazide Real-Time Polymerase Chain Reaction Assay

Molecular techniques based on real-time polymerase chain reaction (qPCR) allow the detection and quantification of DNA but are unable to distinguish between signals from dead or live cells. Because of the lack of simple techniques to differentiate between viable and nonviable cells, the aim of this study was to optimize and evaluate a straightforward test based on propidium monoazide (PMA) dye action combined with a qPCR assay (PMA-qPCR) for the selective quantification of viable/nonviable epimastigotes of Trypanosoma cruzi PMA has the ability to penetrate the plasma membrane of dead cells and covalently cross-link to the DNA during exposure to bright visible light, thereby inhibiting PCR amplification. Different concentrations of PMA (50-200 μM) and epimastigotes of the Maracay strain of T. cruzi (1 × 10(5)-10 parasites/mL) were assayed; viable and nonviable parasites were tested and quantified by qPCR with a TaqMan probe specific for T. cruzi. In the PMA-qPCR assay optimized at 100 μM PMA, a significant qPCR signal reduction was observed in the nonviable versus viable epimastigotes treated with PMA, with a mean signal reduction of 2.5 logarithm units and a percentage of signal reduction > 98%, in all concentrations of parasites assayed. This signal reduction was also observed when PMA-qPCR was applied to a mixture of live/dead parasites, which allowed the detection of live cells, except when the concentration of live parasites was low (10 parasites/mL). The PMA-qPCR developed allows differentiation between viable and nonviable epimastigotes of T. cruzi and could thus be a potential method of parasite viability assessment and quantification.

Chronic Chagas Disease Diagnosis: A Comparative Performance of Commercial Enzyme Immunoassay Tests

There is a significant heterogeneity in reported performance of serological assays for Chagas disease diagnosis. The conventional serology testing in laboratory diagnosis and in blood banks is unsatisfactory because of a high number of inconclusive and misclassified results. We aimed to assess the quality of four commercially available enzyme-linked immunosorbent assay tests for their ability to detect Trypanosoma cruzi antibodies in 685 sera samples. Cross-reactivity was assessed by using 748 sera from patients with unrelated diseases. Initially, we found that the reactivity index against T. cruzi antigen was statistically higher in sera from Chagas disease patients compared with those from non-chagasic patients, supporting the notion that all evaluated tests have a good discriminatory ability toward the diagnosis of T. cruzi infection in patients in the chronic phase of the disease. Although all tests were similarly sensitive for diagnosing T. cruzi infection, there were significant variations in terms of specificity and cross-reactivity among them. Indeed, we obtained divergent results when testing sera from patient with unrelated diseases, particularly leishmaniasis, with the levels of cross-reactivity being higher in tests using whole T. cruzi extracts compared with those using recombinant proteins. Our data suggest that all four tests may be used for the laboratory diagnosis and routine blood screening diagnose for Chagas disease. We also emphasize that, despite their general good performance, caution is needed when analyzing the results when these tests are performed in areas where other diseases, particularly leishmaniasis, are endemic.

Risk Factors and Screening for Trypanosoma cruzi Infection of Dutch Blood Donors

BACKGROUND

Blood donors unaware of Trypanosoma cruzi infection may donate infectious blood. Risk factors and the presence of T. cruzi antibodies in at-risk Dutch blood donors were studied to assess whether specific blood safety measures are warranted in the Netherlands.

METHODOLOGY

Birth in a country endemic for Chagas disease (CEC), having a mother born in a CEC, or having resided for at least six continuous months in a CEC were considered risk factors for T. cruzi infection. From March through September 2013, risk factor questions were asked to all donors who volunteered to donate blood or blood components. Serum samples were collected from donors reporting one or more risk factors, and screened for IgG antibodies to T. cruzi by EIA.

RESULTS

Risk factors for T. cruzi infection were reported by 1,426 of 227,278 donors (0.6%). Testing 1,333 at-risk donors, none (0.0%; 95%, CI 0.0-0.4%) was seroreactive for IgG antibodies to T. cruzi. A total of 472 donors were born in a CEC; 553 donors reported their mother being born in a CEC; and 1,121 donors reported a long-term stay in a CEC. The vast majority of reported risk factors were related to Suriname and Brazil. Overall, the participants resided for 7,694 years in CECs, which equals 2.8 million overnight stays. Of those, 1.9 million nights were spent in Suriname.

CONCLUSIONS/SIGNIFICANCE

Asymptomatic T. cruzi infection appears to be extremely rare among Dutch blood donors. Blood safety interventions to mitigate the risk of T. cruzi transmission by transfusion would be highly cost-ineffective in the Netherlands, and are thus not required.