Epidemiologic and laboratory findings from 3 years of testing United States blood donors for Trypanosoma cruzi

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

BACKGROUND AND OBJECTIVES

Trypanosoma cruzi is the etiologic agent of Chagas disease (CD), an anthropozoonosis from the American continent that progresses from an acute phase to an indeterminate phase, followed by a chronic symptomatic phase in around 30% of patients. In countries where T. cruzi is not endemic, many blood transfusion services test blood donors who have stayed in an endemic country ('at-risk stay')-even if they do not present with other risk factors. However, the efficiency of this approach has been questioned.

MATERIALS AND METHODS

On 18 September 2023, a worldwide survey was distributed among employees of blood transfusion services. The questions mainly pertained to CD's endemicity in the blood services' region, the current testing policy for T. cruzi and the number of confirmed positive results among donors with a prior at-risk stay alone (i.e., without other risk factors for T. cruzi infection).

RESULTS

Twenty-six recipients completed the survey. Of the 22 (84.6%) blood services that operated in a non-endemic region, 9 (42.9%) tested donors for T. cruzi, including 8 (88.9%) that considered the travel history or the duration of the stay (alone) in their testing algorithm ('study blood services'). Over 93 years of observation among all study blood services, 2 donations from donors with an at-risk stay alone and 299 from those with other risk factors were confirmed positive for T. cruzi.

CONCLUSION

The study findings question the utility of testing blood donors who have stayed in an endemic country without other risk factors.

Leveraging Donor Populations to Study the Epidemiology and Pathogenesis of Transfusion-Transmitted and Emerging Infectious Diseases

The tragedy of transfusion-associated hepatitis and HIV spurred a decades-long overhaul of the regulatory oversight and practice of blood transfusion. Consequent to improved donor selection, testing, process control, clinical transfusion practice and post-transfusion surveillance, transfusion in the United States and other high-income countries is now a very safe medical procedure. Nonetheless, pathogens continue to emerge and threaten the blood supply, highlighting the need for a proactive approach to blood transfusion safety. Blood donor populations and the global transfusion infrastructure are under-utilized resources for the study of infectious diseases. Blood donors are large, demographically diverse subsets of general populations for whom cross-sectional and longitudinal samples are readily accessible for serological and molecular testing. Blood donor collection networks span diverse geographies, including in low- and middle-income countries, where agents, especially zoonotic pathogens, are able to emerge and spread, given limited tools for recognition, surveillance and control. Routine laboratory storage and transportation, coupled with data capture, afford access to rich epidemiological data to assess the epidemiology and pathogenesis of established and emerging infections. Subsequent to the State of the Science in Transfusion Medicine symposium in 2022, our working group (WG), "Emerging Infections: Impact on Blood Science, the Blood Supply, Blood Safety, and Public Health" elected to focus on "leveraging donor populations to study the epidemiology and pathogenesis of transfusion-transmitted and emerging infectious diseases." The 5 landmark studies span (1) the implication of hepatitis C virus in post-transfusion hepatitis, (2) longitudinal evaluation of plasma donors with incident infections, thus informing the development of a widely used staging system for acute HIV infection, (3) explication of the dynamics of early West Nile Virus infection, (4) the deployment of combined molecular and serological donor screening for Babesia microti, to characterize its epidemiology and infectivity and facilitate routine donor screening, and (5) national serosurveillance for SARS-CoV-2 during the COVID-19 pandemic. The studies highlight the interplay between infectious diseases and transfusion medicine, including the imperative to ensure blood transfusion safety and the broader application of blood donor populations to the study of infectious diseases.

Characterization of Latin American migrants at risk for Trypanosoma cruzi infection in a non-endemic setting. Insights into initial evaluation of cardiac and digestive involvement

BACKGROUND

Trypanosoma cruzi causes Chagas disease (CD), a potentially fatal disease characterized by cardiac disorders and digestive, neurological or mixed alterations. T. cruzi is transmitted to humans by the bite of triatomine vectors; both the parasite and disease are endemic in Latin America and the United States. In the last decades, population migration has changed the classic epidemiology of T. cruzi, contributing to its global spread to traditionally non-endemic countries. Screening is recommended for Latin American populations residing in non-endemic countries.

METHODS

The present study analyzes the epidemiological characteristics of 2,820 Latin American individuals who attended the International Health Service (IHS) of the Hospital Clinic de Barcelona between 2002 and 2019. The initial assessment of organ damage among positive cases of T. cruzi infection was analyzed, including the results of electrocardiogram (ECG), echocardiogram, barium enema and esophagogram.

RESULTS

Among all the screened individuals attending the clinic, 2,441 (86.6%) were born in Bolivia and 1,993 (70.7%) were female. Of individuals, 1,517 (81.5%) reported previous exposure to the vector, which is a strong risk factor associated with T. cruzi infection; 1,382 individuals were positive for T. cruzi infection. The first evaluation of individuals with confirmed T. cruzi infection, showed 148 (17.1%) individuals with Chagasic cardiomyopathy, the main diagnostic method being an ECG and the right bundle branch block (RBBB) for the most frequent disorder; 16 (10.8%) individuals had a normal ECG and were diagnosed of Chagasic cardiomyopathy by echocardiogram.

CONCLUSIONS

We still observe many Latin American individuals who were at risk of T. cruzi infection in highly endemic areas in their countries of origin, and who have not been previously tested for T. cruzi infection. In fact, even in Spain, a country with one of the highest proportion of diagnosis of Latin American populations, T. cruzi infection remains underdiagnosed. The screening of Latin American populations presenting with a similar profile as reported here should be promoted. ECG is considered necessary to assess Chagasic cardiomyopathy in positive individuals, but echocardiograms should also be considered as a diagnostic approach given that it can detect cardiac abnormalities when the ECG is normal.

A Branched and Double Alpha-Gal-Bearing Synthetic Neoglycoprotein as a Biomarker for Chagas Disease

Chagas disease (CD) is caused by the parasite Trypanosoma cruzi and affects 6-7 million people worldwide. The diagnosis is still challenging, due to extensive parasite diversity encompassing seven genotypes (TcI-VI and Tcbat) with diverse ecoepidemiological, biological, and pathological traits. Chemotherapeutic intervention is usually effective but associated with severe adverse events. The development of safer, more effective therapies is hampered by the lack of biomarker(s) (BMKs) for the early assessment of therapeutic outcomes. The mammal-dwelling trypomastigote parasite stage expresses glycosylphosphatidylinositol-anchored mucins (tGPI-MUC), whose O-glycans are mostly branched with terminal, nonreducing α-galactopyranosyl (α-Gal) glycotopes. These are absent in humans, and thus highly immunogenic and inducers of specific CD anti-α-Gal antibodies. In search for α-Gal-based BMKs, here we describe the synthesis of neoglycoprotein NGP11b, comprised of a carrier protein decorated with the branched trisaccharide Galα(1,2)[Galα(1,6)]Galβ. By chemiluminescent immunoassay using sera/plasma from chronic CD (CCD) patients from Venezuela and Mexico and healthy controls, NGP11b exhibited sensitivity and specificity similar to that of tGPI-MUC from genotype TcI, predominant in those countries. Preliminary evaluation of CCD patients subjected to chemotherapy showed a significant reduction in anti-α-Gal antibody reactivity to NGP11b. Our data indicated that NGP11b is a potential BMK for diagnosis and treatment assessment in CCD patients.

Emerging and reemerging forms of Trypanosoma cruzi transmission

This review aims to update and discuss the main challenges in controlling emergent and reemergent forms of Trypanosoma cruzi transmission through organ transplantation, blood products and vertical transmission in endemic and non-endemic areas as well as emergent forms of transmission in endemic countries through contaminated food, currently representing the major cause of acute illness in several countries. As a neglected tropical disease potentially controllable with a major impact on morbimortality and socioeconomic aspects, Chagas disease (CD) was approved at the WHO global plan to interrupt four transmission routes by 2030 (vector/blood transfusion/organ transplant/congenital). Implementation of universal or target screening for CD are highly recommended in blood banks of non-endemic regions; in organ transplants donors in endemic/non-endemic areas as well as in women at risk from endemic areas (reproductive age women/pregnant women-respective babies). Moreover, main challenges for surveillance are the application of molecular methods for identification of infected babies, donor transmitted infection and of live parasites in the food. In addition, the systematic recording of acute/non-acute cases and transmission sources is crucial to establish databases for control and surveillance purposes. Remarkably, antiparasitic treatment of infected reproductive age women and infected babies is essential for the elimination of congenital CD by 2030.

Endemic parasitic infections in donors and recipients of stem cell and solid organ transplants: focus on strongyloidiasis and Chagas disease

PURPOSE OF REVIEW

The aim of the article is to review recent recommendations on the management of Strongyloidiasis and Chagas disease (ChD) in the context of stem-cell or solid-organ transplantation.

RECENT FINDINGS

An update on laboratory screening, detection of acute disease or reactivation and recommended preventive or therapeutic options in the transplant recipients and donors is presented. Recent epidemiological data showing new estimates on the worldwide burden of both diseases and changes in the classical distribution around the globe should increase awareness and will impact the evaluation and management of transplant recipients and donors in endemic and nonendemic regions.

SUMMARY

Strongyloidiasis and ChD are potentially life threatening if unnoticed in the context of stem-cell or solid-organ transplantation and should be considered in endemic and nonendemic areas. Effective strategies for detection, monitoring, prevention and management are available for both diseases.

Trends and associated characteristics for Chagas disease among women of reproductive age in the United States, 2002 to 2017

Background

American trypanosomiasis, commonly referred to as Chagas disease, is caused by a single cell protozoan known as Trypanosoma cruzi (T. cruzi). Although those affected are mainly in Latin America, Chagas has been detected in the United States (US), Canada and in many European countries due to migration. Few studies have explored the epidemiology of Chagas within the US or changes in disease burden over the past decade. The objective of this study was to explore the trends and associated characteristics for Chagas disease among hospitalized women of reproductive age in the US.

Methods

We analyzed admissions data including socio-demographic and hospital characteristics for inpatient hospitalization for women of reproductive age (15-49 years) in the US from 2002 through 2017. We employed Joinpoint regression analysis to determine trends in the prevalence of Chagas disease over this period.

Results

A total of 487 hospitalizations of Chagas disease were identified, corresponding to 3.7 per million hospitalizations over the study period. The rate statistically increased from 1.6 per million in 2002 to 7.6 per million hospitalizations in 2017. Chagas was most prevalent among older women, Hispanics and those in the highest zip income bracket. The in-hospital mortality rate was about 10 times greater among women with Chagas compared to those without the condition (3.1% versus 0.3%), and the condition tended to be clustered in women treated at large, urban teaching hospitals in the Northeastern region of the US.

Conclusion

Chagas disease diagnosis appears to be increasing among hospitalized women of reproductive age in the US with a 10-fold elevated risk of mortality.

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.

Lack of evidence of seronegative infection in an endemic area of Chagas disease

The diagnosis of Chagas disease is based on the detection of Trypanosoma cruzi (T. cruzi)-specific antibodies. Nonetheless, there is concern about the sensitivity of current serological assays due to reports of T. cruzi PCR positivity among seronegative individuals. The aim of this study was to evaluate if T. cruzi seronegative infections occur in endemic areas. We recruited 2,157 individuals that were identified as having Chagas disease in a public health system database of an endemic region in Brazil. All participants were interviewed and 2,091 had a sample collected for serological and PCR testing. From these, 149 (7.1%) had negative serological results. PCR was positive in 610 samples (31.4%) of the 1,942 seropositive samples but in none of the 149 samples from seronegative participants. True T. cruzi seronegative infections seem to be rare (95% CI 0-3.7) and should not be a concern for blood supply, which relies on antibody screening.

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 Infection among Migrants at the Mexico/Guatemala Border

Chagas disease results in the largest burden, in terms of disability-adjusted-life-years, of any parasitic disease in the Americas. Monitoring Chagas disease among migrants is critical to controlling its spread and to serving the needs of the migrant community. Therefore, we determined the prevalence and correlates of Chagas disease in regional and international migrant populations at the Mexico/Guatemala border. Data were collected as part of a larger study of human immunodeficiency virus (HIV) and migration. Participants were a sample of recent regional and international migrants who used an illicit substance or had recent problem drinking. Trypanosoma cruzi infection was classified as testing positive on two different enzyme-linked immunosorbent assays (ELISAs). Interviewer-administered surveys captured sociodemographics, migration history, Chagas disease knowledge, and access to care. We enrolled 389 recent migrants, and the prevalence of Chagas disease was 3.1%. Only 19% of the participants reported having ever heard of the disease and less than 1% had been previously tested. Trypanosoma cruzi-positive participants were more likely to have been born in a rural area or town than a city (92% yes versus 59% no, P = 0.02) and have recently lived in a house with a makeshift roof (33% yes versus 8% no, P < 0.01), walls (42% yes versus 13% no, P < 0.01), or floor (50% yes versus 21% no, P < 0.02), or cinderblock walls (92% yes versus 63% no, P = 0.04). With migration rapidly changing the distribution of Chagas disease, more work needs to be done to create targeted surveillance programs and provide access to affordable treatment among Latin American migrants.

Prevalence of Chagas Disease in the Latin American-born Population of Los Angeles

Background

According to an estimate from the Centers for Disease Control and Prevention (CDC), Chagas disease (CD) may affect 1.31% of Latin American immigrants in the United States, with >300 000 cases. However, there is a lack of real-world data to support this estimate. Little is known about the actual prevalence of this neglected tropical disease in the United States, and the bulk of those infected are undiagnosed.

Methods

From April 2008 to May 2014, we screened 4,755 Latin American-born residents of Los Angeles County. Blood samples were tested for serologic evidence of CD. We collected demographic data and assessed the impact of established risk factors on CD diagnosis, including sex, country of origin, housing materials, family history of CD, and awareness of CD.

Results

There were 59 cases of CD, for an overall prevalence of 1.24%. Prevalence was highest among Salvadorans (3.45%). Of the 3,182 Mexican respondents, those from Oaxaca (4.65%) and Zacatecas (2.2%) had the highest CD prevalence. Salvadoran origin (aOR = 6.2; 95% CI = 2.8-13.5; P < .001), prior knowledge of CD (aOR = 2.4; 95% CI = 1.0-5.8; P = .047), and exposure to all 3 at-risk housing types (adobe, mud, and thatched roof) (aOR = 2.5; 95% CI = 1.0-6.4; P = .048) were associated with positive diagnosis.

Conclusions

In the largest screening of CD in the United States to date outside of blood banks, we found a CD prevalence of 1.24%. This implies >30 000 people infected in Los Angeles County alone, making CD an important public health concern. Efficient, targeted surveillance of CD may accelerate diagnosis and identify candidates for early treatment.

Does my patient have chronic Chagas disease? Development and temporal validation of a diagnostic risk score

INTRODUCTION

With the globalization of Chagas disease, unexperienced health care providers may have difficulties in identifying which patients should be examined for this condition. This study aimed to develop and validate a diagnostic clinical prediction model for chronic Chagas disease.

METHODS

This diagnostic cohort study included consecutive volunteers suspected to have chronic Chagas disease. The clinical information was blindly compared to serological tests results, and a logistic regression model was fit and validated.

RESULTS

The development cohort included 602 patients, and the validation cohort included 138 patients. The Chagas disease prevalence was 19.9%. Sex, age, referral from blood bank, history of living in a rural area, recognizing the kissing bug, systemic hypertension, number of siblings with Chagas disease, number of relatives with a history of stroke, ECG with low voltage, anterosuperior divisional block, pathologic Q wave, right bundle branch block, and any kind of extrasystole were included in the final model. Calibration and discrimination in the development and validation cohorts (ROC AUC 0.904 and 0.912, respectively) were good. Sensitivity and specificity analyses showed that specificity reaches at least 95% above the predicted 43% risk, while sensitivity is at least 95% below the predicted 7% risk. Net benefit decision curves favor the model across all thresholds.

CONCLUSIONS

A nomogram and an online calculator (available at http://shiny.ipec.fiocruz.br:3838/pedrobrasil/chronic_chagas_disease_prediction/) were developed to aid in individual risk estimation.

A global systematic review of Chagas disease prevalence among migrants

Human migration has been identified as a potential factor for increased Chagas disease risk and has transformed the disease from a Latin American problem to a global one. We conducted a systematic review of the scientific literature between 2004-2014 in order to: summarize recent seroprevalence estimates of Chagas disease among Latin American migrants, in both endemic and non-endemic settings; compare seroprevalence estimates in migrants to countrywide prevalence estimates; and identify risk factors for Chagas disease among migrants. A total of 320 studies were screened and 23 studies were included. We found evidence that the prevalence of Chagas disease is higher than expected in some migrant groups and that reliance on blood donor screening prevalence estimates underestimates the burden of disease. Overall there is a dearth of high quality epidemiologic studies on the prevalence of Chagas disease in migrants, especially among intra-regional migrants within Latin America. Given that this zoonotic disease cannot likely be eradicated, improved surveillance and reporting is vital to continuing control efforts. More accurate health surveillance of both Latin American migrants and the Chagas disease burden will help countries appropriately scale up their response to this chronic disease. Overall, improved estimates of Chagas disease among migrants would likely serve to highlight the real need for better screening, diagnostics, and treatment of individuals living with the disease.

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.

Historical Perspectives on the Epidemiology of Human Chagas Disease in Texas and Recommendations for Enhanced Understanding of Clinical Chagas Disease in the Southern United States

Chagas disease (Trypanosoma cruzi infection) has recently been identified as an important neglected tropical disease in the United States. Anecdotally referred to as a "silent killer," it leads to the development of potentially fatal cardiac disease in approximately 30% of those infected. In an attempt to better understand the potential of Chagas disease as a significant underlying cause of morbidity in Texas, we performed a historical literature review to assess disease burden. Human reports of triatomine bites and disease exposure were found to be prevalent in Texas. Despite current beliefs that Chagas disease is a recently emerging disease, we report historical references dating as far back as 1935. Both imported cases and autochthonous transmission contribute to the historical disease burden in Texas. We end by discussing the current knowledge gaps, and recommend priorities for advancing further epidemiologic studies and their policy implications.

Chagas disease in solid organ and heart transplantation

PURPOSE OF REVIEW

The diagnosis and management of acute and chronic infections with the microorganism Trypanosoma cruzi, which causes Chagas disease, is important in solid organ transplantation in both endemic and nonendemic countries. In this review, we examine recently published data on the topic of Chagas disease in solid organ transplantation, with an emphasis on data relevant to heart transplantation.

RECENT FINDINGS

Most people with chronic T. cruzi infection have the intermediate form of disease, but approximately 2% of infected persons will progress to Chagas cardiomyopathy per year. The risk of T. cruzi transmission with liver or kidney transplantation appears to be substantially less than that with heart transplantation. For patients with Chagas cardiomyopathy undergoing heart transplant, a structured clinical and laboratory monitoring protocol is necessary to monitor for T. cruzi reactivation. Recent data indicate that laboratory monitoring of peripheral blood with polymerase chain reaction testing can identify reactivation prior to the occurrence of symptoms and allograft injury.

SUMMARY

Transplant clinicians should exercise vigilance in surveillance for Chagas disease in both organ donors and recipients. Although Chagas disease may seem uncommon, it is pervasive in endemic and several nonendemic countries, including the United States and Spain.

Evidence of autochthonous Chagas disease in southeastern Texas

Autochthonous transmission of Trypanosoma cruzi in the United States is rarely reported. Here, we describe five newly identified patients with autochthonously acquired infections from a small pilot study of positive blood donors in southeast Texas. Case-patients 1-4 were possibly infected near their residences, which were all in the same region ∼100 miles west of Houston. Case-patient 5 was a young male with considerable exposure from routine outdoor and camping activities associated with a youth civic organization. Only one of the five autochthonous case-patients received anti-parasitic treatment. Our findings suggest an unrecognized risk of human vector-borne transmission in southeast Texas. Education of physicians and public health officials is crucial for identifying the true disease burden and source of infection in Texas.

Factors associated with peridomestic Triatoma sanguisuga (Hemiptera: Reduviidae) presence in southeastern Louisiana

Although rare, there have been isolated reports of autochthonous transmission of Trypanosoma cruzi Chagas in the United States. In June 2006, a human case of domestically transmitted T. cruzi was identified in southern Louisiana. To examine the localized risk of human T. cruzi infection in the area surrounding the initial human case, environmental surveys of households in the area and a serological survey of the residents were performed between September 2008 and November 2009. Human T. cruzi infection was determined using a rapid antigen field test, followed by confirmatory enzyme-linked immunosorbent assay testing in the laboratory. A perimeter search of each participating residence for Triatoma sanguisuga (LeConte), the predominant local triatomine species, was also performed. No participating individuals were positive for antibodies against T. cruzi; however, high levels of T. cruzi infection (62.4%) were detected in collected T. sanguisuga. Households with T. sanguisuga presence were less likely to use air conditioning, and more likely to have either chickens or cats on the property. While the human risk for T cruzi infection in southeastern Louisiana is low, a high prevalence of infected T. sanguisuga does indicate a substantial latent risk for T. cruzi peridomestic transmission. Further examination of the behavior and ecology of T. sanguisuga in the region will assist in refining local T. cruzi risk associations.

Trypanosoma cruzi screening in Texas blood donors, 2008-2012

Chagas disease is an important emerging disease in Texas that results in cardiomyopathy in about 30% of those infected with the parasite Trypanosoma cruzi. Between the years 2008 and 2012, about 1/6500 blood donors were T. cruzi antibody-confirmed positive. We found older persons and minority populations, particularly Hispanic, at highest risk for screening positive for T. cruzi antibodies during routine blood donation. Zip code analysis determined that T. cruzi is associated with poverty. Chagas disease has a significant disease burden and is a cause of substantial economic losses in Texas.

Reactivation of Chagas disease in a bone marrow transplant patient: case report and review of screening and management

We report a patient with an autologous stem cell transplant and history of residence in a Chagas disease (CD) endemic area who developed Chagas reactivation after induction for transplantation. We recommend that patients at risk for CD be screened before transplantation, and patients found to have chronic infection be monitored for reactivation post transplant.

Surveillance of Chagas disease among at-risk blood donors in Italy: preliminary results from Umberto I Polyclinic in Rome

BACKGROUND

Chagas disease is a parasitic disease due to Trypanosoma cruzi, endemic in Central and Southern America, where the protozoon infects about 8-10 million people. In rural areas the infection is acquired mostly through reduviidae insect vectors, whereas in urban ones it is acquired mainly through the transfusion of blood products, vertical transmission and organ transplantation. The important migratory flows of the last decades have focused attention on possible T. cruzi transmission by transfusion also in non-endemic countries, and platelets have been recognised as the main origin of infection for recipients from serologically-positive Latino-American donors.

MATERIALS AND METHODS

In order to avoid the occurrence of transfusion-related cases, in 2010 systematic screening for anti-T. cruzi antibodies was started at the Umberto I Polyclinic in Rome, controlling blood donors born and/or coming from Latin-American countries in which the disease is endemic. The aim of this paper is to report the preliminary results achieved since the introduction of this screening.

RESULTS

Anti-T. cruzi antibodies have been detected to date in 3.9% out of the 128 people examined. A seropositive subject also proved positive by polymerase chain reaction analysis and showed very light parasitaemia.

DISCUSSION

The preliminary results are quite alarming. Indeed, serological findings exceed those reported in other non-endemic countries, and Italian travellers proved to be an insidious possible source of direct transmission. The need for systematic screening of at-risk blood donors also in non-endemic countries is emphasised.

Results of lookback for Chagas disease since the inception of donor screening at New York Blood Center

BACKGROUND

Chagas disease is a parasitic infection by Trypanosoma cruzi, typically transmitted via infected triatomine bug fecal contamination of bite sites. Other routes of infection include congenital, oral, organ transplantation, and blood product transmission.

STUDY DESIGN AND METHODS

From 2007 until 2011, New York Blood Center screened donations for the presence of T. cruzi antibodies using a Food and Drug Administration-approved test. Confirmatory testing was performed and recipients of units donated by confirmed-positive donors were investigated via lookback.

RESULTS

A total of 204 donors were T. cruzi antibody positive representing 0.019% of all donors during this time period (1,066,516 unique donors screened). Of the enzyme-linked immunosorbent assay-reactive donors, 77 were confirmed positive by radioimmunoprecipitation assay (0.007%). At least 154 units from 29 of the confirmed-positive donors had been transfused to 141 recipients. At the time of lookback, 48 of the 141 recipients were alive and seven underwent T. cruzi screening. Two recipients were found to be immunofluorescence assay (IFA) positive. Both IFA-positive recipients received a leukoreduced apheresis platelet unit (two separate donations) from the same confirmed positive donor, a 72-year-old immigrant from Argentina.

CONCLUSIONS

Lookback analysis was able to identify the first two cases of probable transfusion-transmitted T. cruzi infection since implementation of the national screening program, which increases the total number of reported cases in the United States to 8.

Ten-year incidence of Chagas cardiomyopathy among asymptomatic Trypanosoma cruzi-seropositive former blood donors

BACKGROUND

Very few studies have measured disease penetrance and prognostic factors of Chagas cardiomyopathy among asymptomatic Trypanosoma cruzi-infected persons.

METHODS AND RESULTS

We performed a retrospective cohort study among initially healthy blood donors with an index T cruzi-seropositive donation and age-, sex-, and period-matched seronegatives in 1996 to 2002 in the Brazilian cities of São Paulo and Montes Claros. In 2008 to 2010, all subjects underwent medical history, physical examination, ECGs, and echocardiograms. ECG and echocardiogram results were classified by blinded core laboratories, and records with abnormal results were reviewed by a blinded panel of 3 cardiologists who adjudicated the outcome of Chagas cardiomyopathy. Associations with Chagas cardiomyopathy were tested with multivariate logistic regression. Mean follow-up time between index donation and outcome assessment was 10.5 years for the seropositives and 11.1 years for the seronegatives. Among 499 T cruzi seropositives, 120 (24%) had definite Chagas cardiomyopathy, and among 488 T cruzi seronegatives, 24 (5%) had cardiomyopathy, for an incidence difference of 1.85 per 100 person-years attributable to T cruzi infection. Of the 120 seropositives classified as having Chagas cardiomyopathy, only 31 (26%) presented with ejection fraction <50%, and only 11 (9%) were classified as New York Heart Association class II or higher. Chagas cardiomyopathy was associated (P<0.01) with male sex, a history of abnormal ECG, and the presence of an S3 heart sound.

CONCLUSIONS

There is a substantial annual incidence of Chagas cardiomyopathy among initially asymptomatic T cruzi-seropositive blood donors, although disease was mild at diagnosis.

Antibody levels correlate with detection of Trypanosoma cruzi DNA by sensitive polymerase chain reaction assays in seropositive blood donors and possible resolution of infection over time

BACKGROUND

The clinical significance of anti-Trypanosoma cruzi low-level reactive samples is incompletely understood. Polymerase chain reaction (PCR)-positive rates and antibody levels among seropositive blood donors in three countries are described.

STUDY DESIGN AND METHODS

Follow-up samples were collected from T. cruzi-seropositive donors from 2008 through 2010 in the United States (n = 195) and Honduras (n = 58). Also 143 samples from Brazil in 1996 to 2002, originally positive by three serologic assays, were available and paired with contemporary follow-up samples from these donors. All samples were retested with Ortho enzyme-linked immunosorbent assay (ELISA). PCR assays were performed on coded sample panels by two laboratories (Blood Systems Research Institute [BSRI] and American Red Cross Holland Laboratory [ARC]) that amplified kinetoplast minicircle DNA sequences of T. cruzi.

RESULTS

PCR testing at BSRI yielded slightly higher overall sensitivity and specificity (33 and 98%) compared with those at the ARC (28 and 94%). Among seropositive donors, PCR-positive rates varied by country (p < 0.0001) for the BSRI laboratory: Brazil (57%), Honduras (32%), and the United States (14%). ELISA signal-to-cutoff ratios (S/CO) were significantly higher for PCR-positive compared to PCR-negative donors (p < 0.05 for all comparisons). Additionally, PCR-negative Brazilian donors exhibited greater frequencies of antibody decline over time versus PCR-positive donors (p = 0.003).

CONCLUSION

For all three countries, persistent DNA positivity correlated with higher ELISA S/CO values, suggesting that high-level seroreactivity reflects chronic parasitemia. Significant S/CO declines in 10% of the PCR-negative Brazilian donors may indicate seroreversion after parasite clearance in the absence of treatment.