Rapid Diagnostic Tests Evaluated for Chronic Chagas Disease Patients

Chagas is a disease caused by the parasite Trypanosoma cruzi, and is one of the most important public health concerns affecting the population of Latin America. This disease presents an acute phase that generally goes undiagnosed and a chronic phase with cardiac manifests principally, is diagnosed through serological tests that are generally not available.

In the Americas, up to 99% of cases of Chagas Disease (CD) and more than 90% of cases of CD in Europe are undiagnosed. Serological diagnosis in the chronic phase of CD is based on the detection of circulating antibodies through conventional reactions such as the enzyme-linked immunosorbent assay (ELISA) test, Indirect Immunofluorescence (IIF), Indirect Hemagglutination (IHA), Chemiluminescence (ChLIA) and Western blot/Immunoblot.


A group of international scientists led by the Universitat Autònoma de Barcelona (Barcelona, Spain) evaluated the diagnostic precision of two rapid diagnostic tests (RDT’s) on patients with chronic CD. They included in the study 305 participants from rural and urban area of Colombia of which 215 were negative for T. cruzi and 90 were positive according to the reference criteria. Of the participants, 60.7% were women, 39.3% were men, the median age was 47.1 ± 18.5years old, the youngest participant was 3 years old and the oldest participant was 80 years old.

All samples were analyzed using the ELISA Chagas III tests (GrupoBios, Santiago, Chile) and with the Chagas ELISA IgG+IgM tests (Vircell, Granada, Spain) as reference standards. The Two RDT’s were performed to all participants were the Chagas Detect Plus (CDP, InBios, Seattle, WA, USA) and the Chagas Stat-Pak (CSP, Chembio Diagnostic, Hauppauge, NY, USA).

The scientists reported that 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.

The authors concluded that the findings demonstrated 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. The study was published on June 2, 2021 in the journal PLOS Neglected Tropical Diseases.

Related Links:
Universitat Autònoma de Barcelona
GrupoBios
Vircell
InBios
Chembio Diagnostic