Rapid immunochromatographic tests for the diagnosis of chronic Chagas disease in at-risk populations: A systematic review and meta-analysis

The use of rapid diagnostic tests for chronic Chagas disease: An expert meeting report

Chagas disease, caused by Trypanosoma cruzi, affects millions of people globally and is associated with significant underdiagnosis and undertreatment. Current diagnostic algorithms face challenges in remote regions. We aimed to review the potential of rapid diagnostic tests (RDTs) for screening or diagnosing chronic Chagas disease in endemic areas. An expert panel representing scientific and academic institutions from the Americas convened with the aim of discussing the use of RDTs. The study employed the nominal group technique, gathering insights from diverse experts during a 3-day meeting. Panel discussions covered RDT application, research protocols, and regulatory mechanisms. The results indicate that RDTs play a crucial role in surveillance and screening, although limitations in sensitivity and specificity exist. The expert group recommends standardized protocols, emphasizes the importance of cost-effectiveness assessments, and highlights the need to consider geographic validation. Despite these challenges, RDTs present a promising avenue for improving Chagas disease diagnosis in resource-limited settings. Future research and a collaborative approach are deemed essential for effective implementation.

A guide for the generation of repositories of clinical samples for research on Chagas disease

Chagas disease, caused by the parasite Trypanosoma cruzi, affects over 6 million people, mainly in Latin America. Two different clinical phases, acute and chronic, are recognised. Currently, 2 anti-parasitic drugs are available to treat the disease (nifurtimox and benznidazole), but diagnostic methods require of a relatively complex infrastructure and trained personnel, limiting its widespread use in endemic areas, and the access of patients to treatment. New diagnostic methods, such as rapid tests (RDTs) to diagnose chronic Chagas disease, or loop-mediated isothermal amplification (LAMP), to detect acute infections, represent valuable alternatives, but the parasite's remarkable genetic diversity might make its implementation difficult. Furthermore, determining the efficacy of Chagas disease treatment is complicated, given the slow reversion of serological anti-T. cruzi antibody reactivity, which may even take decades to occur. New biomarkers to evaluate early therapeutic efficacy, as well as diagnostic tests able to detect the wide variety of circulating genotypes, are therefore, urgently required. To carry out studies that address these needs, high-quality and traceable samples from T. cruzi-infected individuals with different geographical backgrounds, along with associated clinical and epidemiological data, are necessary. This work describes the framework for the creation of such repositories, following standardised and uniform protocols, and considering the ethical, technical, and logistic aspects of the process. The manual can be adapted according to the resources of each laboratory, to guarantee that samples are obtained in a reproducible way, favouring the exchange of data among different work groups, and their generalizable evaluation and analysis. The main objective of this is to accelerate the development of new diagnostic methods and the identification of biomarkers for Chagas disease.

Comparative evaluation of four rapid diagnostic tests that detect human Trypanosoma cruzi-specific antibodies to support diagnosis of Chagas Disease in urban population of Argentina

BACKGROUND

Chagas disease (CD), caused by the parasite Trypanosoma cruzi, is the most important endemic anthropozoonosis in Argentina. Since 2010, the World Health Organization has highlighted the urgent need to validate diagnostic systems that allow rapid detection of T. cruzi, infection in primary healthcare centers. Serological rapid diagnostic tests (RDTs) for T. cruzi, infection could be used to improve case management, as RDTs do not require specialized laboratories or highly trained staff to use them. We aimed to generate unbiased performance data of RDTs in Argentina, to evaluate their usefulness for improving T. cruzi, diagnosis rates.

METHODS AND PRINCIPAL FINDINGS

This is a retrospective, laboratory-based, diagnostic evaluation study to estimate the clinical sensitivity/specificity of four commercially available RDTs for T. cruzi, using the Chagas disease diagnostic algorithm currently used in Argentina as the reference standard. In total, 400 serum samples were tested, 200 from individuals with chronic T. cruzi infection and 200 from individuals not infected with T. cruzi. All results were registered as the agreement of at least two operators who were blinded to the reference standard results. The sensitivity estimates ranged from 92.5-100% (95% confidence interval (CI) lower bound 87.9-98.2%); for specificity, the range was 76-96% (95% CI lower bound 69.5-92.3%). Most RDTs evaluated showed performances comparable with the reference standard method, showing almost perfect concordance (Kappa 0.76-0.92).

CONCLUSIONS

Our study demonstrates that, under controlled laboratory conditions, commercially available RDTs for CD have a performance comparable to the Argentinian diagnostic algorithm, which is based on laboratory-based serological tests. For the next stage of our work, the RDTs will be evaluated in real-world settings.

Comparative evaluation of lateral flow assays to diagnose chronic Trypanosoma cruzi infection in Bolivia

Bolivia has the highest incidence of Chagas disease (CD) worldwide. Caused by the parasite Trypanasoma cruzi, CD is generally a chronic condition. Diagnosis is logistically and financially challenging, requiring at least two different laboratory-based serological tests. Many CD cases are missed; in Bolivia it is estimated just 6% of individuals chronically infected with T. cruzi get diagnosed. Achieving control on the way to elimination of CD requires a radical simplification of the current CD testing pathways, to overcome the barriers to accessing CD treatment. We aimed to generate unbiased performance data of lateral flow assays (LFAs) for T. cruzi infection in Bolivia, to evaluate their usefulness for improving T. cruzi diagnosis rates in a precise and efficient manner. This retrospective, laboratory-based, diagnostic evaluation study sought to estimate the sensitivity/specificity of 10 commercially available LFAs for T. cruzi, using the current CD diagnostic algorithm employed in Bolivia as the reference test method. All tests were blinded at the study site and performed by three operators. In total, 470 serum samples were tested, including 221 and 249 characterized as CD-positive/-negative, respectively. The LFAs were scored according to their relative importance using a decision-tree-based algorithm, with the mean decrease in Gini index as the scoring metric. The estimates of sensitivities ranged from 62.2-97.7% (95% confidence interval (CI) lower bound 55.0-94.7%); for specificities the range was 78.6-100% (95% CI lower bound 72.0-97.5%); 5/10 and 6/10 tests had sensitivity >90% and specificity >95%, respectively. Four LFAs showed high values of both sensitivity (93-95%) and specificity (97-99%). The agreement between 6 LFAs and the reference tests was almost perfect (Kappa 0.83-0.94). Most LFAs evaluated thus showed performances comparable with current laboratory-based diagnostic methods.

Laboratory evaluation of eleven rapid diagnostic tests for serological diagnosis of Chagas disease in Colombia

BACKGROUND

Chagas disease is a public health challenge in Colombia, where only an estimated 1.2% of people at risk have accessed diagnosis, while less than 0.5% of affected people have obtained treatment. The development of simplified diagnostic algorithms would enable progress in access to diagnosis; however, the current diagnostic algorithm relies on at least two laboratory-based tests that require qualified personnel, processing equipment, and infrastructure, which are still generally lacking at the primary care level. Rapid diagnostic tests (RDTs) for Chagas disease could simplify diagnosis, but their performance in the epidemiological context of Colombia is not well known.

METHODOLOGY

A retrospective analytical observational study of RDTs was performed to estimate the operational characteristics of 11 commercially available RDTs designed for in vitro detection of anti-T. cruzi IgG antibodies. The study was performed under controlled laboratory conditions using human serum samples.

PRINCIPAL FINDINGS

Eleven RDTs were assessed, ten using 585 serum samples and one using 551 serum samples. Employing the current national diagnostic algorithm as a reference standard for serological diagnosis of chronic infection, the sensitivity of the assessed RDTs ranged from 75.5% to 99.0% (95% CI 70.5-100), while specificity ranged from 70.9% to 100% (95% CI 65.3-100). Most tests (7/11, 63.6%) had sensitivity above 90%, and almost all (10/11, 90.9%) had specificity above 90%. Five RDTs had both sensitivity and specificity above 90%.

CONCLUSIONS/SIGNIFICANCE

The evaluation of these 11 commercially available RDTs under controlled laboratory conditions is a first step in the assessment of the diagnostic performance of RDTs in Colombia. As a next step, field studies will be conducted on available RDTs with sensitivity and specificity greater than 90% in this study, to evaluate performance in real world conditions, with the final goal to allow simplified diagnostic algorithms.

Opportunistic Community Screening of Chronic Chagas Disease Using a Rapid Diagnosis Test in Pharmacies in Barcelona (Catalonia, Spain): Study Protocol and Pilot Phase Results

Objectives: This study aimed to report the protocol and results from the pilot phase of an opportunistic CP-based CD screening program in Barcelona, Spain.

Methods: Three strategies according to recruitment approach were designed: passive, active and active-community. The study process consisted of signing the informed consent form, recording the patient’s data in a web-based database system, and performing the rapid test and blood collection on dry paper.

Results: Nineteen pharmacies participated and 64 patients were included during the pilot phase of the study. The rapid diagnostic test (RDT) was positive in 2/64 (3.13%) cases. Of the 49 DBS samples that arrived at the laboratory, 22 (45%) were collected incorrectly. After quantitative and qualitative assessment of the program, the dry paper sample and passive strategy were ruled out.

Conclusion: DBS sampling and the passive strategy are not suitable for CD screening in community pharmacies. There is a need to expand the number of participating pharmacies and individuals to determine whether conducting a RDT in community pharmacies is an effective screening method to increase access to CD diagnosis in a non-endemic area.

Accuracy of Diagnostic Tests for the Detection of Chagas Disease: A Systematic Review and Meta-Analysis

The present systematic review and meta-analysis about the accuracy of diagnostic tests aim to describe the findings of literature over the last thirty years for the diagnosis of Chagas disease (CD). This work aimed to determine the accuracy of diagnostic techniques for CD in the disease's acute and chronic phases. The PubMed database was searched for studies published between 1990 and 2021 on CD diagnostics. Fifty-six published studies that met the criteria were analyzed and included in the meta-analysis, evaluating diagnostic accuracy through sensitivity and specificity. For Enzyme-Linked Immunosorbent Assay (ELISA), Fluorescent Antibody Technique (IFAT), Hemagglutination Test (HmT), Polymerase Chain Reaction (PCR), and Real-Time Polymerase Chain Reaction (qPCR) diagnosis methods, the sensitivity had a median of 99.0%, 78.0%, 75.0%, 76.0%, and 94.0%, respectively; while specificity presented a median of 99.0%, 99.0%, 99.0%, 98.0%, and 98.0%, respectively. This meta-analysis showed that ELISA and qPCR techniques had a higher performance compared to other methods of diagnosing CD in the chronic and acute phases, respectively. It was concluded utilizing the Area Under the Curve restricted to the false positive rates (AUCFPR), that the ELISA diagnostic test presents the highest performance in diagnosing acute and chronic CD, compared to serological and molecular tests. Future studies focusing on new CD diagnostics approaches should be targeted.

Rapid diagnostic tests and ELISA for diagnosing chronic Chagas disease: Systematic revision and meta-analysis

OBJECTIVE

To determine the diagnostic validity of the enzyme-linked immunosorbent assay (ELISA) and Rapid Diagnostic Tests (RDT) among individuals with suspected chronic Chagas Disease (CD).

METHODOLOGY

A search was made for studies with ELISA and RDT assays validity estimates as eligibility criteria, published between 2010 and 2020 on PubMed, Web of Science, Scopus, and LILACS. This way, we extracted the data and assessed the risk of bias and applicability of the studies using the QUADAS-2 tool. The bivariate random effects model was also used to estimate the overall sensitivity and specificity through forest-plots, ROC space, and we visually assessed the heterogeneity between studies. Meta-regressions were made using subgroup analysis. We used Deeks' test to assess the risk of publication bias.

RESULTS

43 studies were included; 27 assessed ELISA tests; 14 assessed RDTs; and 2 assessed ELISA and RDTs, against different reference standards. 51.2 % of them used a non-comparative observational design, and 46.5 % a comparative clinical design ("case-control" type). High risk of bias was detected for patient screening and reference standard. The ELISA tests had a sensitivity of 99% (95% CI: 98-99) and a specificity of 98% (95% CI: 97-99); whereas the Rapid Diagnostic Tests (RDT) had values of 95% (95% CI: 94-97) and 97% (95% CI: 96-98), respectively. Deeks' test showed asymmetry on the ELISA assays.

CONCLUSIONS

ELISA and RDT tests have high validity for diagnosing chronic Chagas disease. The analysis of these two types of evidence in this systematic review and meta-analysis constitutes an input for their use. The limitations included the difficulty in extracting data due to the lack of information in the articles, and the comparative clinical-type design of some studies.

Leishmaniasis and Chagas disease: Is there hope in nanotechnology to fight neglected tropical diseases?

Nanotechnology is revolutionizing many sectors of science, from food preservation to healthcare to energy applications. Since 1995, when the first nanomedicines started being commercialized, drug developers have relied on nanotechnology to improve the pharmacokinetic properties of bioactive molecules. The development of advanced nanomaterials has greatly enhanced drug discovery through improved pharmacotherapeutic effects and reduction of toxicity and side effects. Therefore, highly toxic treatments such as cancer chemotherapy, have benefited from nanotechnology. Considering the toxicity of the few therapeutic options to treat neglected tropical diseases, such as leishmaniasis and Chagas disease, nanotechnology has also been explored as a potential innovation to treat these diseases. However, despite the significant research progress over the years, the benefits of nanotechnology for both diseases are still limited to preliminary animal studies, raising the question about the clinical utility of nanomedicines in this field. From this perspective, this review aims to discuss recent nanotechnological developments, the advantages of nanoformulations over current leishmanicidal and trypanocidal drugs, limitations of nano-based drugs, and research gaps that still must be filled to make these novel drug delivery systems a reality for leishmaniasis and Chagas disease treatment.

Diagnosis and Clinical Management of Chagas Disease: An Increasing Challenge in Non-Endemic Areas

Chagas disease (CD) is caused by the parasite Trypanosoma cruzi, and it is endemic in Central, South America, Mexico and the South of the United States. It is an important cause of early mortality and morbidity, and it is associated with poverty and stigma. A third of the cases evolve into chronic cardiomyopathy and gastrointestinal disease. The infection is transmitted vertically and by blood/organ donation and can reactivate with immunosuppression. Case identification requires awareness and screening programmes targeting the population at risk (women in reproductive age, donors, immunocompromised patients). Treatment with benznidazole or nifurtimox is most effective in the acute phase and prevents progression to chronic phase when given to children. Treating women antenatally reduces but does not eliminate vertical transmission. Treatment is poorly tolerated, contraindicated during pregnancy, and has little effect modifying the disease in the chronic phase. Screening is easily performed with serology. Migration has brought the disease outside of the endemic countries, where the transmission continues vertically and via blood and tissue/organ donations. There are more than 32 million migrants from Latin America living in non-endemic countries. However, the infection is massively underdiagnosed in this setting due to the lack of awareness by patients, health authorities and professionals. Blood and tissue donation screening policies have significantly reduced transmission in endemic countries but are not universally established in the non-endemic setting. Antenatal screening is not commonly done. Other challenges include difficulties accessing and retaining patients in the healthcare system and lack of specific funding for the interventions. Any strategy must be accompanied by education and awareness campaigns directed to patients, professionals and policy makers. The involvement of patients and their communities is central and key for success and must be sought early and actively. This review proposes strategies to address challenges faced by non-endemic countries.

Parasitological, serological and molecular diagnosis of acute and chronic Chagas disease: from field to laboratory

There is no consensus on the diagnostic algorithms for many scenarios of Trypanosoma cruzi infection, which hinders the establishment of governmental guidelines in endemic and non-endemic countries. In the acute phase, parasitological methods are currently employed, and standardised surrogate molecular tests are being introduced to provide higher sensitivity and less operator-dependence. In the chronic phase, IgG-based serological assays are currently used, but if a single assay does not reach the required accuracy, PAHO/WHO recommends at least two immunological tests with different technical principles. Specific algorithms are applied to diagnose congenital infection, screen blood and organ donors or conduct epidemiological surveys. Detecting Chagas disease reactivation in immunosuppressed individuals is an area of increasing interest. Due to its neglect, enhancing access to diagnosis of patients at risk of suffering T. cruzi infection should be a priority at national and regional levels.

Worldwide Control and Management of Chagas Disease in a New Era of Globalization: a Close Look at Congenital Trypanosoma cruzi Infection

Population movements have turned Chagas disease (CD) into a global public health problem. Despite the successful implementation of subregional initiatives to control vectorial and transfusional Trypanosoma cruzi transmission in Latin American settings where the disease is endemic, congenital CD (cCD) remains a significant challenge. In countries where the disease is not endemic, vertical transmission plays a key role in CD expansion and is the main focus of its control. Although several health organizations provide general protocols for cCD control, its management in each geopolitical region depends on local authorities, which has resulted in a multitude of approaches. The aims of this review are to (i) describe the current global situation in CD management, with emphasis on congenital infection, and (ii) summarize the spectrum of available strategies, both official and unofficial, for cCD prevention and control in countries of endemicity and nonendemicity. From an economic point of view, the early detection and treatment of cCD are cost-effective. However, in countries where the disease is not endemic, national health policies for cCD control are nonexistent, and official regional protocols are scarce and restricted to Europe. Countries of endemicity have more protocols in place, but the implementation of diagnostic methods is hampered by economic constraints. Moreover, most protocols in both countries where the disease is endemic and those where it is not endemic have yet to incorporate recently developed technologies. The wide methodological diversity in cCD diagnostic algorithms reflects the lack of a consensus. This review may represent a first step toward the development of a common strategy, which will require the collaboration of health organizations, governments, and experts in the field.

An immunochromatography strip with peroxidase-mimicking ferric oxyhydroxide nanorods-mediated signal amplification and readout

Immunochromatography testing strips (ICTs) promise to become the point-of-care test format for early diagnosis due to their convenience, low cost, and simplification. However, the insufficient signal intensity and limited sensitivity of this format hamper their application. Herein, we overcame these limitations by integrating rod-like ferric oxyhydroxide (β-FeOOH) nanoparticles with ICTs. By varying the concentration of PEI, a one-pot, mild-temperature hydrolysis method was adapted for the synthesis and morphology regulation of β-FeOOH nanorod. Due to the excellent enzyme-like catalytic activity toward peroxidase substrates (TMB) in the presence of hydrogen peroxide (H₂O₂), the β-FeOOH nanorod in ICTs served as a signal generator and the nanozyme for signal amplification. The proof-of-concept work was performed for the detection of human chorionic gonadotropin (hCG). A two fold improvement of detection sensitivity was achieved compared to the sensitivity of conventional Au NPs-based ICTs. These results show that β-FeOOH-based ICT has a potential application in POCT detection in clinical diagnostics.

Combined use of two rapid tests for the conclusive diagnosis of Chagas disease: a systematic scoping review

OBJECTIVE

The goal of this systematic scoping review is to collect and summarise scientific evidence regarding the validity of two simultaneous immunochromatographic tests for the conclusive diagnosis of Chagas disease. The research was informed by the following review questions: Will the use of two rapid tests be a valid method for the definitive diagnosis of Chagas disease when compared with conventional serological tests? In what type of population has the operation of two rapid tests been tried for the diagnosis of Chagas disease? What are the biomedical and public health advantages of the diagnostic method resulting from the combination of two rapid tests over the conventional serological method? Will it be a cost-benefit strategy for the diagnosis of Chagas with respect to conventional serological tests?

DESIGN

Systematic scoping review.

SETTING

A search of the published and unpublished literature in five databases was carried out, in order to identify, screen and select the studies included in this review.

RESULTS

468 studies were identified, of which 46 were screened with a full-text reading, and finally, three articles were included in the review. All studies were in endemic countries with adult and paediatric populations (n=1133) and, together, they evaluated four different rapid tests. The rapid tests showed good sensitivity (97.4%-100%) and specificity (96.1%-100%) for the diagnosis of Chagas when used in combination and compared with the reference tests.

CONCLUSIONS

The simultaneous use of at least two immunochromatographic rapid tests is a valid option for the definitive diagnosis of chronic Chagas in endemic rural areas, as long as there are studies that previously evaluate their performance on the areas of implementation. Therefore, this could be an alternative to the current diagnostic standard. However, additional studies are still needed in more countries in order to provide further evidence and to investigate the cost-benefit.

Analytical Evaluation of Dried Blood Spot and Rapid Diagnostic Test as a New Strategy for Serological Community Screening for Chronic Chagas Disease

Background

Chagas disease is a public health problem not only in Latin America, but also in other regions, including Spain, due to migration movements. Conventional serological diagnosis requires an invasive sample (plasma or serum) and a well-equipped laboratory. To circumvent those limitations, blood samples dried on filter paper (DBS) or Rapid Diagnostic Test (RDT) could be a practical alternative to reference protocol for serological screening in epidemiological studies. We evaluated the usefulness of dried blood sampling and a rapid diagnostic test (Trypanosoma Detect™) for the detection of antibodies against T. cruzi for their use in community-based screening.

Methodology/Principal Findings

A total of 162 stored paired whole-blood and serum samples from Latin American migrants and 25 negative-control blood samples were included. Diagnosis of chronic Chagas disease was performed in serum according to WHO algorithms. Blood samples were retrospectively collected as dried spots and then analyzed using two different serological techniques, enzyme-linked immunosorbent assay (ELISA) and electrochemiluminescence immunoassay (E-CLIA). Whole-blood samples were also used to evaluate a rapid diagnostic test based on immunochromatography. A better correlation with conventional serum was observed in dried blood elutes using E-CLIA than ELISA (97% vs. 77% sensitivity, respectively). Both assays reported 100% specificity. The median cut-off index values of E-CLIA for dried blood were significantly lower than those for serum (138.1 vs. 243.3, P<0.05). The Trypanosoma Detect™ test presented a sensitivity and specificity of 89.6% and 100%, respectively.

Conclusions

The detection of antibodies against T. cruzi in dried blood samples shows a higher sensitivity when using E-CLIA compared with ELISA. Trypanosoma Detect™ is easier to use but has a lower sensitivity. Hence, we propose a sequential strategy based on performing the rapid test first, and a negative result will be confirmed by DBS-ECLIA for use in community Chagas disease screening programs.

Geographic variations in test reactivity for the serological diagnosis of Trypanosoma cruzi infection

Chagas disease is a neglected disease caused by Trypanosoma cruzi parasites. Most diagnosis is based on serological tests, but the lack of a gold standard test complicates the measurement of test performance. To overcome this limitation, we used samples from a cohort of well-characterized T. cruzi-infected women to evaluate the reactivity of two rapid diagnostic tests and one enzyme-linked immunosorbent assay (ELISA). Our cohort was derived from a previous study on congenital transmission of T. cruzi and consisted of 481 blood/plasma samples from Argentina (n = 149), Honduras (n = 228), and Mexico (n = 104), with at least one positive T. cruzi PCR. Reactivity of the three tests ranged from 70.5% for the Wiener ELISA to 81.0% for the T-Detect and 90.4% for the Stat-Pak rapid tests. Test reactivity varied significantly among countries and was highest in Argentina and lowest in Mexico. When considering at least two reactive serological tests to confirm seropositivity, over 12% of T. cruzi infection cases from Argentina were missed by serological tests, over 21% in Honduras, and an alarming 72% in Mexico. Differences in test performance among countries were not due to differences in parasitemia, but differences in antibody levels against ELISA antigens were observed. Geographic differences in T. cruzi parasite strains as well as genetic differences among human populations both may contribute to the discrepancies in serological testing. Improvements in serological diagnostics for T. cruzi infections are critically needed to ensure an optimum identification of cases.

Sensitivity and Specificity of two rapid tests for the diagnosis of infection by Trypanosoma cruzi in a Colombian population

OBJECTIVE

To evaluate diagnostic precision of two rapid diagnostic tests (RDT's) on patients with chronic Chagas disease.

METHODOLOGY

Prospective study with the following inclusion criteria: subjects older than 3 years, signed informed consent. Exclusion criterion: subjects could not have previously received treatment for infection with T. cruzi. The study population were participants in a screening process undertaken in rural and urban zones of the department Boyacá, Colombia. Two RDT's were performed to all participants: the Chagas Detect Plus InBios (CDP) and the Chagas Stat-Pak (CSP) and as a reference standard the ELISA Chagas III GrupoBios and the Chagas ELISA IgG+IgM I Vircell tests were used. In the case of discordant results between the two ELISA tests, an indirect immunofluorescence was done.

RESULTS

Three hundred-five (305) subjects were included in the study (38 patients with leishmaniasis), of which 215 tested negative for T cruzi and 90 tested positive according to the reference standard. The sensitivity of the RDT's were 100% (CI 95% 95.9-100), and the specificity of the CDP was 99.1% (CI 95% 96.6-99.8) and for CSP was 100% (CI 95% 98.3-100). The agreement of CDP was 99.5% and for CSP was 100% with Kappa values of (k = 99.1; CI 95% 92.6-99.8%) and (k = 100; CI 95% 94.3-100), respectively. RDT's did not present cross-reactions with samples from patients who were positive for leishmaniasis.

CONCLUSIONS

The findings demonstrate excellent results from the RDT's in terms of validity, safety, and reproducibility. The results obtained provide evidence for the recommendation for using these tests in a Colombian epidemiological context principally in endemic areas in which laboratory installations necessary to perform conventional tests are not available, or they are scarce and to help in diagnosing chronic Chagas disease in order to provide access to treatment as soon as possible.

Chagas disease screening in pregnant Latin American women: Adherence to a systematic screening protocol in a non-endemic country

BACKGROUND

Chagas disease (CD) is a chronic parasitic disease caused by Trypanosoma cruzi and is endemic to continental Latin America. In Spain, the main transmission route is congenital. We aimed to assess adherence to regional recommendations of universal screening for CD during pregnancy in Latin American women in the province of Alicante from 2014 to 2018.

METHODOLOGY/PRINCIPAL FINDINGS

Retrospective quality study using two data sources: 1) delivery records of Latin American women that gave birth in the 10 public hospitals of Alicante between January 2014 and December 2018; and 2) records of Chagas serologies carried out in those centers between May 2013 and December 2018. There were 3026 deliveries in Latin American women during the study period; 1178 (38.9%) underwent CD serology. Screening adherence ranged from 17.2% to 59.3% in the different health departments and was higher in Bolivian women (48.3%). Twenty-six deliveries (2.2%) had a positive screening; CD was confirmed in 23 (2%) deliveries of 21 women. Bolivians had the highest seroprevalence (21/112; 18.7%), followed by Colombians (1/333; 0.3%) and Ecuadorians (1/348; 0.3%). Of 21 CD-positive women (19 Bolivians, 1 Colombian, 1 Ecuadorian), infection was already known in 12 (57.1%), and 9 (42.9%) had already been treated. Only 1 of the 12 untreated women (8.3%) was treated postpartum. Follow-up started in 20 of the 23 (87.0%) neonates but was completed only in 11 (47.8%); no cases of congenital transmission were detected. Among the 1848 unscreened deliveries, we estimate 43 undiagnosed cases of CD and 1 to 2 undetected cases of congenital transmission.

CONCLUSIONS/SIGNIFICANCE

Adherence to recommendations of systematic screening for CD in Latin American pregnant women in Alicante can be improved. Strategies to strengthen treatment of postpartum women and monitoring of exposed newborns are needed. Currently, there may be undetected cases of congenital transmission in our province.

Evaluation of 2 Lateral Flow Rapid Tests in the Diagnosis of Chagas Disease in the Washington Metropolitan Area

We compared the accuracy of the Stat-Pak and Chagas Detect Plus with a latent class analysis. Sensitivity values of 89.7% and 91.9% and specificities of 97.1% and 80.3%, respectively, were seen in the serodiagnosis of Chagas disease in Hispanic immigrants, revealing the limitations of these tests in diverse populations.

How effective are rapid diagnostic tests for Chagas disease?

Introduction: Diagnosis of chronic Chagas disease relies on the agreement of two conventional serological tests based on distinct antigens. These require cold to preserve reagents and samples, and equipment and trained personnel to run them. Moreover, results turnaround may be delayed for several weeks risking a loss to follow-up of infected subjects, summoning major disadvantages to access diagnosis (and treatment) in many highly endemic areas.Areas covered: Recent studies have shown the versatility of rapid diagnostic tests for the detection of chronic Trypanosoma cruzi infections in referral centers and in field campaigns, with a performance equivalent to that of conventional tools. Remarkably, RDTs do not require cold storage and provide results within an hour. Additionally, they are easy-to-use and can work with a tiny volume of finger-pricked whole blood. Altogether, major advantages toward generalizing their use as an alternative to conventional tests.Expert opinion: Already in 2021, only a small percentage of T. cruzi-infected people are diagnosed and treated. The unsuitability of currently used diagnostics, and of the recommended algorithm, to the conditions found in many regions do not help to fill this gap. RDTs stand as a promising solution, even though geographical validation should precede their implementation.

Risk Factors for Maternal Chagas Disease and Vertical Transmission in a Bolivian Hospital

BACKGROUND

Vertical transmission of Trypanosoma cruzi infection accounts for a growing proportion of new cases of Chagas disease. Better risk stratification is needed to predict which women are more likely to transmit the infection.

METHODS

This study enrolled women and their infants at the Percy Boland Women's Hospital in Santa Cruz, Bolivia. Pregnant women were screened for Chagas disease by rapid test and received confirmatory serology. Infants of seropositive mothers underwent diagnostic testing with quantitative polymerase chain reaction (qPCR).

RESULTS

Among 5,828 enrolled women, 1,271 (21.8%) screened positive for Chagas disease. Older maternal age, family history of Chagas disease, home conditions, lower education level, and history of living in a rural area were significantly associated with higher adjusted odds of maternal infection. Of the 1,325 infants of seropositive mothers, 65 infants (4.9%) were diagnosed with congenital Chagas disease. Protective factors against transmission included Cesarean delivery (adjusted OR [aOR]: 0.60, 95% CI: 0.36-0.99) and family history of Chagas disease (aOR: 0.58, 95% CI: 0.34-0.99). Twins were significantly more likely to be congenitally infected than singleton births (OR: 3.32, 95% CI: 1.60-6.90). Among congenitally infected infants, 32.3% had low birth weight, and 30.8% required hospitalization after birth.

CONCLUSIONS

Although improved access to screening and qPCR increased the number of infants diagnosed with congenital Chagas disease, many infants remain undiagnosed. A better understanding of risk factors and improved access to highly sensitive and specific diagnostic techniques for congenital Chagas disease may help improve regional initiatives to reduce disease burden.

Rapid Diagnostic Tests for Trypanosoma cruzi Infection: Field Evaluation of Two Registered Kits in a Region of Endemicity and a Region of Nonendemicity in Argentina

Infection by Trypanosoma cruzi (Chagas disease [ChD]) affects around 7 million people in the Americas, most of whom are unaware of their status due to lack of clinical manifestations and poor access to diagnosis. Rapid diagnostic tests (RDTs) are widely used for screening for different infections (HIV, hepatitis B, and syphilis), and their application for ChD would facilitate access to diagnosis, especially in remote areas where health services have scarce resources. We conducted a prospective intervention study in 2018 to evaluate in the field two in vitro RDTs for ChD, authorized by the National Administration of Medicaments, Aliments, and Medical Technologies of Argentina (ANMAT), in areas of endemicity and nonendemicity in Argentina.

Infection by Trypanosoma cruzi (Chagas disease [ChD]) affects around 7 million people in the Americas, most of whom are unaware of their status due to lack of clinical manifestations and poor access to diagnosis. Rapid diagnostic tests (RDTs) are widely used for screening for different infections (HIV, hepatitis B, and syphilis), and their application for ChD would facilitate access to diagnosis, especially in remote areas where health services have scarce resources. We conducted a prospective intervention study in 2018 to evaluate in the field two in vitro RDTs for ChD, authorized by the National Administration of Medicaments, Aliments, and Medical Technologies of Argentina (ANMAT), in areas of endemicity and nonendemicity in Argentina. We recruited 607 volunteers older than 18 years in Salta province and the city of Buenos Aires. The RDTs Ab Standard Diagnostics SD Bioline (SD) and Check Chagas Wiener Lab (WL) were performed in situ with whole-blood samples, and confirmatory serology was done at a reference center. The rate of infection with T. cruzi was 17.8% (108/607). The SD test showed 97.2% sensitivity (95% confidence interval [CI], 93.5 to 100) and 91.7% specificity (95% CI, 96.2 to 99.2%), and the WL test showed 93.4% sensitivity (95% CI, 88.2 to 98.6%) and 99.1% specificity (95% CI, 91.9 to 100%). The sensitivity and specificity for the two RDTs tested were higher than previously reported. These results encourage the use of the tested RDTs in Salta province and for further field studies for the implementation of these RDTs in other epidemiological scenarios. This will be very important to improve access to diagnosis of Chagas and its clinical management as a neglected disease, especially in remote areas with health access barriers.

Overcoming challenges in the diagnosis and treatment of parasitic infectious diseases in migrants

Introduction: Recent increases in population movements have created novel health challenges in many areas of the World, and health policies have been adapted accordingly in several countries. However, screening guidelines for infectious diseases are not standardized and generally do not include comprehensive screening for parasitic infections.Areas covered: Malaria, Chagas disease, leishmaniasis, amebiasis, filariases, strongyloidiasis, and schistosomiasis are reviewed, focusing on the challenges posed for their diagnosis and management in vulnerable populations such as migrants. The methodology included literature searches in public databases such as PubMed.gov and Google Scholar and search of the US National Library of Medicine online database of privately and publicly funded clinical studies (ClinicalTrials.gov) until November 2019.Expert opinion: Parasitic infections which may remain asymptomatic for prolonged periods, leading to chronic infection and complications, and/or may be transmitted in non-endemic areas are ideal candidates for screening. Proposed strategies to improve diagnosis in vulnerable groups such as migrants include facilitating access to healthcare in a multi-dimensional manner considering location, individual characteristics, and timing. Limitations and availability of specific diagnostic techniques should be addressed and focus on drug and vaccine development for these neglected infections should be prioritized through collaborative initiatives with public disclosure of results.

Use of rapid diagnostic tests (RDTs) for conclusive diagnosis of chronic Chagas disease - field implementation in the Bolivian Chaco region

Chagas disease, caused by the parasite Trypanosoma cruzi, is the neglected tropical disease with a highest burden in Latin America. Its acute stage is mostly asymptomatic and goes unnoticed. Symptoms appear at the chronic stage, which is when diagnosis is usually made. This is based on the agreement of two conventional serological tests such as Enzyme-Linked Immunosorbent Assays (ELISAs). There are commercial kits with good sensitivity and specificity but their use is impractical in many highly endemic regions with poorly equipped laboratories. Luckily, several rapid diagnostic tests (RDTs) are available for the detection of anti-T. cruzi immunoglobulins. They are easy to operate, require no cold storage, provide fast turnaround of results, and some can work with a tiny volume of whole blood as sample. With the aim to field validate their use we compared an alternative algorithm based on a combination of RDTs with the standard based on ELISAs. In both cases a third test was available in case of discordance. RDTs were implemented by mobile teams in field campaigns to detect chronic T. cruzi-infections in the Chaco region of Bolivia. ELISAs were made in the reference laboratories located in the main hospitals of Yacuiba and Villa Montes, two major cities of the region. We enrolled 685 subjects who voluntarily participated in the study and had not been treated against the disease before. The agreement between the two main RDTs was 93.1% (638/685) (kappa index = 0.86; CI 95% 0.83–0.90). In comparison to the ELISAs algorithm, the combined use of the RDTs provided a sensitivity of 97.7% and a specificity of 96.1%. These results support the use of RDTs for the diagnosis of chronic Chagas disease in the studied region, and encourage their evaluation in other regions of Bolivia and other endemic countries.

Chagas disease is caused by the parasite Trypanosoma cruzi. It affects ~7 million people worldwide, exerting its highest impact in Latin America. The acute stage of the infection is generally asymptomatic and goes undiagnosed and untreated. It is in the long lasting chronic stage that the life-threatening heart and/or gut tissue disruptions may occur. Then diagnosis is performed by serological detection of T. cruzi-specific immunoglobulins in the patients´ sera, usually upon suspicion of the clinical symptomatology. Such diagnosis may arrive too late for those with advanced tissue damage as there are evidences indicating that the treatment might be ineffective for them. It is thus of huge importance to provide an early diagnosis to get access to treatment. But the use of current conventional serological tools is not possible in many highly endemic regions distant from equipped reference laboratories. Herein we evaluate an alternative algorithm for the conclusive diagnosis of chronic Chagas disease based on the use of rapid diagnostic tests (RDTs) in a field study made in the Chaco region of Bolivia. Comparison of the RDTs performance with that of the ELISAs “gold-standard” yielded a sensitivity of 97.7% and a specificity of 96.1%. These values justify a wider use of the RDTs in the region under study, and encourage their evaluation in other regions of Bolivia and other endemic countries.

Chagas disease in Italy: the study's contribution of Italian researchers

Chagas disease (CD) is an emerging infection in Italy as the consequence of the huge immigration from Latin American countries observed during the last ten-fifteen years. However, the interest of Italian researchers on CD dates back to the '80-90s of the last century with studies conducted in collaboration with Brazilian and Argentinian colleagues by Italian cardiologists and pathologists. Moreover, the first demonstration of the existence in the pre-Columbian America of Chagas disease in a Peruvian mummy was made by a group of Italian paleopathologists. Seroprevalence studies performed between 2010-2014 in Negrar (Verona), Bergamo, Milan, Florence and Rome shows Trypanosoma cruzi infection ranging from 3.9% to 17.1% with people coming from Bolivia as the most affected. As observed in Latin America about 30% of screened subjects in Italy are affected by cardiac or digestive forms of CD. More than 20% of subjects treated with benznidazole discontinued it permanently due to adverse events.