Chagas’ disease diagnosis: a rapid lateral chromatographic assay using recombinant proteins of Trypanosoma cruzi.

RACCA AL; MARECHAL S; ZELUZ D; PAPER T; MARCIPAR I

Mar del Plata (Bs As)

Congreso; IX Congreso Argentino de Protozoología y Enfermedades Parasitarias; 2011

Sociedad Argentina de Protozoología

Chagas’ disease is an infection caused by the parasite Trypanosoma cruzi, mainly occurring in Latin American countries where the parasite vector bug, Triatoma infestans, is widespread. This illness has been estimated to affect between 16 and 18 million people, with a further 100 million considered at risk, according to the World Health Organization (WHO). The broadly used serological assays to diagnose T. cruzi infection in present clinical practice are indirect haemagglutination (IHA), indirect immunofluorescence, and enzyme-linked immunosorbent assay (ELISA). Diagnosis with these conventional assays is routinely conducted in laboratories based in large urban centers. However, most Chagas’ disease patients live in periurban and rural areas where neither equipped laboratories nor skilled human resources are available. Immunoquick Chagas test (Biosynex, France) is a rapid immunochromatographic assay in development for detection of antibody to T. cruzi. This methodology uses small volume samples such as one serum drop, and allows acquiring results in 15 min, therefore being useful to perform the test in the field, without the need of refrigerator to preserve reagents. It is composed of an absorbent pad, a nitrocellulose membrane striped with a control line reagent, a test line reagent with chimeric recombinant T. cruzi antigens and a conjugate pad that contains dried detector reagent. We evaluated serum samples from T. cruzi-infected patients (n =100) which were obtained from the Regional Hospital of Reconquista (Santa Fe, Argentina). Chagas’ disease-negative serum samples without other reactivity (n =102) were obtained from donors from the same hospital. Conventional assays, commercial ELISA and IHA from Wiener Lab (Argentina), were used for diagnostic classification and served for comparison for the Biosynex quick test. The rapid test performance was also compared with OPERON Chagas Test. In the present study, the rapid diagnostic test correctly detected 99 of the 100 positive results identified by the conventional assays, yielding 99% sensitivity. Likewise, of the 102 negative results according to conventional assays, 94 were correctly categorized by this rapid test, yielding 92.2% specificity. For the same panel OPERON Kit sensibility and specificity was 95% and 96%, respectively. The results of this evaluation indicate that the Biosynex quick test has great potential as a new rapid assay for scrrening purposes.