Chagas disease and liver transplantation: Experience in Argentina using real-time quantitative PCR for early detection and treatment

No longer stuck in the past: new advances in artificial intelligence and molecular assays for parasitology screening and diagnosis

PURPOSE OF REVIEW

Emerging technologies are revolutionizing parasitology diagnostics and challenging traditional methods reliant on microscopic analysis or serological confirmation, which are known for their limitations in sensitivity and specificity. This article sheds light on the transformative potential of artificial intelligence and molecular assays in the field, promising more accurate and efficient detection methods.

RECENT FINDINGS

Artificial intelligence has emerged as a promising tool for blood and stool parasite review, when paired with comprehensive databases and expert oversight result in heightened specificity and sensitivity of diagnoses while also increasing efficiency. Significant strides have been made in nucleic acid testing for multiplex panels for enteric pathogen. Both multiplex and single target panels for Plasmodium , Babesia , filaria, and kinetoplastids have been developed and garnered regulatory approval, notably for blood donor screening in the United States. Additional technologies such as MALDI-TOF, metagenomics, flow cytometry, and CRISPR-Cas are under investigation for their diagnostic utility and are currently in the preliminary stages of research and feasibility assessment.

SUMMARY

Recent implementation of artificial intelligence and digital microscopy has enabled swift smear screening and diagnosis, although widespread implementation remains limited. Simultaneously, molecular assays - both targeted and multiplex panels are promising and have demonstrated promise in numerous studies with some assays securing regulatory approval recently. Additional technologies are under investigation for their diagnostic utility and are compelling avenues for future proof-of-concept diagnostics.

Chagas disease in the immunocompromised host

PURPOSE OF REVIEW

To highlight recent advances in our understanding of Trypanosoma cruzi infection in immunocompromised individuals, a condition that is increasingly recognized as populations shift and use of immunosuppressive medications becomes more commonplace.

RECENT FINDINGS

Chagas disease screening programs should include people at risk for both Chagas disease and immunocompromise, e.g. people who have resided for ≥6 months in endemic Latin America who have an immunocompromising condition such as HIV or who are planned to start an immunosuppressive medication regimen. The goal of identifying such individuals is to allow management strategies that will reduce their risk of T. cruzi reactivation disease. For people with HIV- T. cruzi coinfection, strict adherence to antiretroviral therapy is important and antitrypanosomal treatment is urgent in the setting of symptomatic reactivation. People at risk for T. cruzi reactivation due to immunosuppression caused by advanced hematologic conditions or postsolid organ transplantation should be monitored via T. cruzi qPCR and treated with preemptive antitrypanosomal therapy if rising parasite load on serial specimens indicates reactivation. Reduction of the immunosuppressive regimen, if possible, is important.

SUMMARY

Chronic Chagas disease can lead to severe disease in immunocompromised individuals, particularly those with advanced HIV (CD4 + < 200 cells/mm 3 ) or peri-transplantation.

Reactivation of Trypanosoma cruzi infection in immunosuppressed patients: a systematic review and meta-analysis

BACKGROUND

The risk of Trypanosoma cruzi reactivation is poorly understood. Previous studies evaluating the risk of reactivation report imprecise findings, and recommendations for monitoring and management from clinical guidelines rely on consensus opinion.

OBJECTIVES

We conducted a systematic review and meta-analysis to estimate the cumulative T. cruzi reactivation incidence in immunosuppressed adults, summarize the available evidence on prognostic factors for reactivation, and examine its prognostic effect on mortality.

DATA SOURCES

MEDLINE, Embase, LILACS, Clinical Trials, and CENTRAL from inception to 4 July 2022.

STUDY ELIGIBILITY CRITERIA

Studies reporting the incidence of T. cruzi reactivation.

PARTICIPANTS

Immunosuppressed adults chronically infected by T. cruzi.

METHODS

Two authors independently extracted data (including, but not limited to, incidence data, reactivation definition, follow-up, treatment, monitoring schedule, examined prognostic factors) and evaluated the risk of bias. We pooled cumulative incidence using a random-effects model.

RESULTS

Twenty-two studies (806 participants) were included. The overall pooled incidence of T. cruzi reactivation was 27% (95% CI, 19-36), with the highest pooled proportion in the sub-group of transplant recipients (36%; 95% CI, 25-48). The highest risk period was in the first 6 months after transplant (32%; 95% CI, 17-58), decreasing drastically the number of new cases later. People living with HIV and patients with autoimmune diseases experienced significantly lower cumulative reactivation incidences (17%; 95% CI, 8-29 and 18%; 95% CI, 9-29, respectively). A single study explored the independent effect of benznidazole and found benefits for preventing reactivations. No studies evaluated the independent association between reactivation and mortality, while sensitivity analysis results using unadjusted estimates were inconclusive. The heterogeneity of diagnostic algorithms was substantial.

CONCLUSIONS

Reactivation occurs in three out of ten T. cruzi-seropositive immunosuppressed adults. These findings can assist clinicians and panel guidelines in tailoring monitoring schedules. There is a great need for an accurate definition of reactivation and targeted monitoring.

Chagas disease in immunocompromised patients

SUMMARYAs Chagas disease remains prevalent in the Americas, it is important that healthcare professionals and researchers are aware of the screening, diagnosis, monitoring, and treatment recommendations for the populations of patients they care for and study. Management of Trypanosoma cruzi infection in immunocompromised hosts is challenging, particularly because, regardless of antitrypanosomal treatment status, immunocompromised patients with Chagas disease are at risk for T. cruzi reactivation, which can be lethal. Evidence-based practices to prevent and manage T. cruzi reactivation vary depending on the type of immunocompromise. Here, we review available data describing Chagas disease epidemiology, testing, and management practices for various populations of immunocompromised individuals, including people with HIV and patients undergoing solid organ and hematopoietic stem cell transplantation.

Quantitative PCR-Based Diagnosis and Follow-up of Chagas Disease Primary Infection After Solid Organ Transplant: A Multicentre Study

Chagas disease in solid organ transplant recipients may present as a primary infection (PI). Early detection is crucial for timely treatment. This is the largest observational multicentre study evaluating qPCR for early diagnosis and treatment monitoring of PI in seronegative recipients of organs from seropositive donors. Of 34 patients admitted at 5 health centers, PI was detected by qPCR in 8 (23.5%) within a posttransplant period of 40 days (interquartile range [IQR], 31-50 days). No PI was detected by the Strout test or clinical symptoms/signs. All patients had favorable treatment outcome with negative qPCR 31 days (IQR, 18-35 days) after treatment, with no posttreatment relapse episodes.

Use of sera cell free DNA (cfDNA) and exovesicle-DNA for the molecular diagnosis of chronic Chagas disease

Chagas disease, a neglected tropical disease, is now considered a worldwide health concern as a result of migratory movements from Central and South America to other regions that were considered free of the disease, and where the epidemiological risk is limited to transplacental transmission or blood or organ donations from infected persons. Parasite detection in chronically ill patients is restricted to serological tests that only determine infection by previous infection and not the presence of the parasite, especially in patients undergoing treatment evaluation or in newborns. We have evaluated the use of nucleic acids from both circulating exovesicles and cell-free DNA (cfDNA) from 50 samples twice randomly selected from a total of 448 serum samples from immunologically diagnosed patients in whom the presence of the parasite was confirmed by nested PCR on amplicons resulting from amplification with kinetoplastid DNA-specific primers 121F-122R. Six samples were randomly selected to quantify the limit of detection by qPCR in serum exovesicles. When the nucleic acids thus purified were assayed as a template and amplified with kinetoplastid DNA and nuclear satellite DNA primers, a 100% positivity rate was obtained for all positive samples assayed with kDNA-specific primers and 96% when SAT primers were used. However, isolation of cfDNA for Trypanosoma cruzi and amplification with SAT also showed 100% positivity. The results demonstrate that serum exovesicles contain DNA of mitochondrial and nuclear origin, which can be considered a mixed population of exovesicles of parasitic origin. The results obtained with serum samples prove that both cfDNA and Exovesicle DNA can be used to confirm parasitaemia in chronically ill patients or in samples where it is necessary to demonstrate the active presence of the parasite. The results confirm for the first time the existence of exovesicles of mitochondrial origin of the parasite in the serum of those affected by Chagas disease.

Transplantation for chagas' disease: closing the knowledge gap

PURPOSE OF THE REVIEW

This review examines the most recent literature on the epidemiology and treatment of Chagas Disease and the risk of Chagas Disease Reactivation and donor-derived disease in solid organ transplant recipients.

RECENT FINDINGS

Chagas disease is caused by infection with the parasite Trypansoma cruzi . In nonendemic countries the disease is seen primarily in immigrants from Mexico, Central America and South America where the disease is endemic. Benznidazole or nifurtimox can be used for treatment. Posaconazole and fosravuconazole did not provide any additional benefit compared to benznidazole alone or in combination. A phase 2 randomized controlled trial suggests that shorter or reduced dosed regimes of benznidazole could be used. Based on a large randomized controlled trial, benznidazole is unlikely to have a significant preventive effect for established Chagas cardiomyopathy. Transplantation has become the treatment of choice for individuals with refractory Chagas cardiomyopathy. Cohort studies show similar posttransplant outcomes for these patients compared to other indications. Transplant candidates and donors with chronic T. cruzi infection are at risk for Chagas disease reactivation and transmitting infection. Screening them via serology is the first line of prevention. Recipients with chronic infection and those receiving organs from infected donors should undergo sequential monitoring with polymerase chain reaction for early detection of reactivation and preemptive treatment with antitrypanosomal therapy.

SUMMARY

Patients with chronic T. cruzi infection can be safely transplanted and be noncardiac organ donors.

Aplastic Anemia and Chagas Disease: T. cruzi Parasitemia Monitoring by Quantitative PCR and Preemptive Antiparasitic Therapy

Background: Aplastic anemia is a rare and life-threatening condition, seldomly witnessed concomitantly with Chagas disease. We aim to discuss the management of these patients under risk of chronic Chagas disease reactivation (CDR), a severe condition with a high morbimortality that occurs in chronic Chagas disease patients under immunosuppression. Case reports: Trypanosoma cruzi (T. cruzi) parasitemia was monitored in three patients for 4−58 months by conventional PCR (cPCR), quantitative PCR (qPCR), microhematocrit/buffy coat, blood culture, and/or xenodiagnosis. One patient received antiparasitic treatment (benznidazole) and the other received allopurinol. Although parasitemia was controlled during and after benznidazole treatment at 300 mg/d for 51 days, in one patient, hematologic parameters worsened continuously before, during, and after treatment. Allopurinol led only to the temporary suppression of T. cruzi parasitemia in the second patient, but after danazol and hematological improvement, parasitemia became undetectable until the end of monitoring. Discussion and Conclusion: Unexpected undetectable or low parasitemia by cPCR/qPCR was reported. We show that the monitoring of parasitemia by qPCR and the use of preemptive therapy when the parasitemia was positive proved to be beneficial to our patients. As a result of the toxicity of more effective antiparasitics, shorter regimens of benznidazole or less toxic drugs in preemptive therapy are options that deserve future studies.

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.

Anti-infective chemoprophylaxis after solid-organ transplantation

INTRODUCTION

Solid organ transplant (SOT) recipients are at high risk of opportunistic infections due to bacterial, viral, fungal, and parasitic pathogens. Anti-infective prophylaxis is a time-tested proven strategy for the prevention of these infections after SOT. Areas covered: The current recommendations for the prevention of surgical site infections, herpes simplex, cytomegalovirus, invasive fungal infections, and selected parasitic diseases are highlighted. Recent peer-reviewed publications on the prevention of infection after SOT were reviewed and their significance was discussed in the context of the current recommendations for preventing infectious complications. Expert commentary: The authors comment on the current approaches to infection prevention in transplant recipients, and discuss how these recommendations are implemented in their clinical practice. Notable findings published during the past year were highlighted, and their clinical significance was interpreted in the context of current recommendations. The evolution of diagnostic and immunologic assays was emphasized, with focus on their potential role in optimizing the current antimicrobial approaches to infection prevention after SOT.