Accuracy of a Rapid Diagnostic Test (Cypress Chagas Quick Test®) for the Diagnosis of Chronic Chagas Disease in a Nonendemic Area: A Retrospective Longitudinal Study

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.

Screening of at-risk blood donors for Chagas disease in non-endemic countries: Lessons from a 2-year experience in Tuscany, Italy

Background

Chagas disease (CD) is caused by the protozoan parasite Trypanosoma cruzi and is transmitted by blood‐sucking triatomine insects in endemic areas of Latin America. Transmission can also occur via blood transfusion and is a major cause of CD in non‐endemic areas.

Objectives

The aim of the study was to assess the prevalence of anti‐T. cruzi antibodies in blood donors at risk of infection in Tuscany, Italy, following the introduction of blood safety Italian legislation.

Material and methods

Donors (N = 1985) were tested in 2016 to 2018 for anti‐T. cruzi IgG using an immunochromatographic test (ICT). Chemiluminescent immunoassay (CLIA) was performed on ICT‐positive donors to exclude CD, whereas enzyme‐linked immunosorbent assay and western blot were performed in case of discordant results. All assays were performed on CD patients (N = 10) for validation.

Results

Ten blood donors had a positive ICT result, with a resulting T. cruzi seroprevalence of 0.5% but demonstrated negative results to CLIA, as well as to the other serological assays. The comparison of serological assays suggested a lower relative sensitivity of ICT.

Conclusion

The results of this study confirm the significance of serological testing in the screening strategy for CD. However, they provide evidence for discontinuing the use of ICT as a screening test and suggest that a sensitive, specific and multi‐sample format assay should be used at the national level for uniformity of results.

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.

Development of a New Lateral Flow Assay Based on IBMP-8.1 and IBMP-8.4 Chimeric Antigens to Diagnose Chagas Disease

Despite several available methodologies for Chagas disease (CD) serological screening, the main limitation of chronic CD diagnosis is the lack of effective tools for large-scale screening and point-of-care diagnosis to be used in different CD epidemiological scenarios. Taking into account that developing such a diagnostic tool will significantly improve the ability to identify CD carriers, we aimed at performing a proof-of-concept study (phase I study) to assess the use of these proteins in a point-of-care platform using serum samples from different geographical settings of Brazil and distinct clinical presentations. The diagnostic accuracy study was conducted on a panel of two WHO International Standards (IS) and 14 sera from T. cruzi-positive and 16 from T. cruzi-negative individuals. The results obtained with the test strips were converted to digital images, allowing quantitative comparison expressed as a relative band intensity ratio (RBI). The diagnostic potential and performance were also determined. Regardless of the geographical origin or clinical presentation, all sera with T. cruzi antibodies returned positive both for IBMP-8.1 and IBMP-8.4 chimeric antigens. The area under the ROC curve (AUC) values was 100% for both antigens, demonstrating an outstanding overall diagnostic accuracy (100%). Based on the data, we believe that the lateral flow assays based on these antigens are promising methodologies for screening CD.

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.

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

BACKGROUND

Despite of a high disease burden, mainly in Latin America, Chagas disease (CD) is underdiagnosed and undertreated. Rapid diagnostic tests (RDTs) might improve the access to diagnosis. The aim of this study is to review the accuracy of commercially available RDTs used in field conditions for the diagnosis of chronic CD in populations at risk, in endemic and non-endemic countries.

METHODS/PRINCIPAL FINDINGS

We undertook a comprehensive search of the following databases: PubMed, SCOPUS, LILACS (last up-date on the 01st July, 2017), without language or date limits. Non-electronic sources have been also searched. This review included clinical studies with cohort recruitment of individuals at risk of T. cruzi exposure, without age limits; adequate reference standards for the diagnosis of CD. We excluded case-control studies and those testing RDTs during acute CD. Data on test accuracies were pooled through a bivariate random-effects model. Only one index test was evaluated separately. Geographical area, commercial brand, disease prevalence, study size, and risk of bias were explored as possible source of heterogeneity. Values of sensitivity and specificity were computed to obtain summary positive/negative likelihood ratios, and summary diagnostic odds ratio. Ten studies were included on six different immunochromatographic RDTs. The pooled sensitivity and specificity of the RDTs resulted 96.6% (95% CI 91.3-98.7%) and 99.3% (95% CI 98.4-99.7%), respectively. Test accuracy was particularly good in endemic areas (98.07%/99.03% of sensitivity/specificity, respectively). One test (Stat-Pak) showed an overall sensitivity of 97% (95% CI 87.6-99.3) and specificity of 99.4% (95% CI 98.6-99.8).

CONCLUSIONS/SIGNIFICANCE

RDTs demonstrated to be sufficiently accurate to recommend their use for screening in endemic areas, even as stand-alone tests. This approach might increase the accessibility to the diagnosis. However, an additional confirmatory test in case of positive result remains a prudent approach.

Tropheryma whipplei intestinal colonization in Italian and migrant population: a retrospective observational study

AIM

To obtain the first molecular epidemiological survey of Tropheryma whipplei intestinal colonization in Italy. Materials & methods: Retrospective, observational study to assess the prevalence of T. whipplei, the causative agent of Whipple's disease, in stool samples (real-time PCR) of patients attending the Center for Tropical Diseases (Italy) and risk factors associated.

RESULTS

Overall prevalence was 6.9% (85/1240). The younger age group showed a significantly higher rate than older age group (12.7 vs 5.9%, p = 0.002). The prevalence was 4.9% for Italians and 9.3% for migrants (p = 0.003). Among the latter, children less than 10 years had higher prevalence than older ones (17.3 vs 7.3%, p = 0.003). The young age, male gender and Giardia duodenalis and Entamoeba histolytica coinfection were risk factors.

CONCLUSION

Our study confirms an increased risk of acquiring T. whipplei infection during childhood, under poor sanitary conditions.

Chagas disease knocks on our door: a cross-sectional study among Latin American immigrants in Milan, Italy

OBJECTIVES

We aimed to assess the prevalence and risk factors for Chagas disease (CD) in Latin American immigrants and to evaluate the accuracy of diagnostic tests. Moreover, we offered to all positive subjects a complete free-of-charge clinical/instrumental evaluation as well as benznidazole treatment in order to stage the disease and verify drug tolerability.

METHODS

A cross-sectional survey of CD among Latin Americans living in Milan and its metropolitan area was conducted between July 2013 and July 2014. Blood samples were tested for serologic evidence of CD together with a questionnaire covering demographic and clinical-epidemiological information.

RESULTS

Forty-eight (9.6%) of the 501 tested subjects were conclusively diagnosed as having CD. The highest prevalence of CD was among those from Bolivia (43/169, 25.4%) and El Salvador (4/68, 5.9%). Older age (adjusted odds ratio (aOR)] 1.05, p =0.004), a Bolivian origin (aOR 8.80; p =0.003), being born in the department of Santa Cruz (aOR 3.72, p =0.047), having lived in mud houses (aOR 2.68; p =0.019), and having an affected relative (aOR 12.77, p =0.001) were independently associated with CD. The ARCHITECT Chagas test showed the highest sensitivity (100%) and specificity (99.8%). Twenty-nine of the subjects with CD (60.4%) underwent disease staging, 10 of whom (35.7%) showed cardiac and/or digestive involvement. Benznidazole treatment was associated with high frequency of adverse reactions (19/27, 70.4%) and permanent discontinuation (8/27, 29.6%).

CONCLUSIONS

CD is highly prevalent among Bolivians and Salvadorans living in Milan. Regions with a large Latin American immigrant population should implement programmes of active detection and treatment.