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ABSTRACT
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.
Article highlights
The use of conventional serological tests for the detection of chronic T. cruzi infections is not practical in many highly endemic regions with low resources. This is mainly due to the scarcity of appropriately equipped laboratories and trained personnel, and to the current delay in results turnaround that risks the loss to follow-up of infected people.
Rapid diagnostic tests (RDTs) were developed as an easy-to-use alternative to conventional tests. They do not require cold-chain, can work with a tiny volume of finger-pricked whole blood, and very importantly, they provide results in less than one hour.
Although the performance of RDTs is geographically variable, likely related to the predominant circulating strains and the infection prevalence, recent studies in Argentina and Bolivia have pointed out their high sensitivity and specificity. Joint to their capacity to be used in field screening campaigns, even outdoors, make of them incredibly valuable tools for the mass screening of chronic Chagas disease.
If proved to work as good as conventional tests upon regional validation, RDTs should be used for the diagnosis of chronic T. cruzi infections. A more widespread use of these tools will promote access to diagnosis in many regions where this is now hindered, which could result as well in an increased access to treatment and thus an improved control of Chagas disease.
WHO/PAHO recommended algorithm for the diagnosis of chronic T. cruzi infections entails the agreement of at least two tests based on different sets of antigens to convey a conclusive result. This doubles the diagnosis costs and has an impact on the time to communicate the outcome. The very high sensitivity and specificity rendered by currently available tests suggest that such recommendation could be re-visited.
Declaration of interest
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
Reviewer disclosures
Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.