Geographic Variation in the Sensitivity of Recombinant Antigen-based Rapid Tests for Chronic Trypanosoma cruzi Infection

Abstract

Chagas disease affects 8-11 million people throughout the Americas. Early detection is crucial for timely treatment and to prevent non-vectorial transmission. Recombinant antigen-based rapid tests had high sensitivity and specificity in laboratory evaluations, but no Peruvian specimens were included in previous studies. We evaluated Stat-Pak and Trypanosoma Detect rapid tests in specimens from Bolivia and Peru. Specimens positive by three conventional assays were confirmed positives; specimens negative by two or more assays were confirmed negatives. In Bolivian specimens, Stat-Pak and Trypanosoma Detect tests were 87.5% and 90.7% sensitive, respectively; both showed 100% specificity. Sensitivity in Peruvian specimens was much lower: 26.6-33.0% (Stat-Pak) and 54.3-55.2% (Trypanosoma Detect); both had specificities > 98%. Even in Bolivian specimens, these sensitivities are inadequate for stand-alone screening. The low sensitivity in Peru may be related to parasite strain differences. Chagas disease rapid tests should be field tested in each geographic site before widespread implementation for screening.

Autonomic Dysfunction and Risk Factors Associated with Trypanosoma cruzi Infection among Children in Arequipa, Peru

“…Our previous work shows that the immunological responses to whole epimastigote lysate and recombinant antigens are substantially lower than in specimens from Bolivia. 40 The risk factors that we identified for urban transmission of Chagas disease were quite similar to those found in rural epidemiological studies. 20,22,41 Not surprisingly, household members' reports of triatomine infestation as well as traces of triatomine exuvia or feces in the child's room were very strong predictors of infection.…”

Diagnosis of Chagas disease: what has been achieved? What remains to be done with regard to diagnosis and follow up studies?

“…Recombinant antigens have been employed in rapid tests with promising results (Roddy et al 2008, Verani et al 2009). …”

Rapid Detection of Trypanosoma cruzi in Human Serum by Use of an Immunochromatographic Dipstick Test

“…Immunochromatographic dipstick tests have been developed for a range of tropical diseases, including malaria (31), leishmaniasis (7), and schistosomiasis (3); until recently (4,5,8,14,17,20,25,28,30), none was available for Chagas disease.…”