We investigated the in vitro action of an hydrosoluble 2-nitroimidazole, Etanidazole (EZL), against Trypanosoma cruzi, the etiologic agent of Chagas disease. EZL displayed lethal activity against isolated trypomastigotes as well as amastigotes of T. cruzi (RA strain) growing in Vero cells or J774 macrophages, without affecting host cell viability. Although not completely equivalent to Benznidazole (BZL), the reference drug for Chagas chemotherapy, EZL takes advantage in exertingits anti-T. cruzi activity for longer periods without serious toxic side effects, as those recorded in BZL-treated patients. Our present results encourage further experiments to study in depth the trypanocidal properties of this drug already licensed for use in human cancers.

The ELISA technique for detection of T. cruzi circulating antigens (cAg) and immune complexes (CIC) in the sera of chronic chagasic patients was field-tested in a well-known endemic area of Argentina (San Luis province). Of 215 individuals screened, 51 were positive for ELISA-CIC and 45 for ELISA-cAg. Seventy four subjects were considered por T. cruzi-infected, as they showed Serologic reactivity at least by two different techniques. In this group, 49 (66.21%) were ELISA-CIC positive, whereas in 43 (58.11%) of them cAg was found by ELISA. Unspecific reactions were observed in only 2 cases with reactive serology for Chagas disease. Within the group considered as noninfected, a false-positive outcome was obtained at low dilution by one of the Serologic tests in 16 (11.35%) of 141 individuals. These sera yielded consistently negative results by ELISA-CIC and cAg, showing the utility of antigen detection in situations of conflictive serology. While antibody determination merely provides an indirect proof of infection, our ELISA tests for demonstration of T. cruzi-specific antigenic fractions in the host's circulation allow a parasitologic diagnosis in chronic patients, with higher sensitivity than that exhibited by traditional methods for detection of the whole parasite

En una zona endémica de la República Argentina se llevó a cabo un ensayo de campo de la prueba inmunoenzimática ELISA para la detección de antígenos (cAg) y complejos inmunes circulantes (CIC) en sueros de pacientes chagásicos crónicos. Del total de 215 muestras de sangre analizadas, 51 fueron positivas para ELISA-CIC y 45 lo fueron para ELISA-cAg. De los 74 (34,32% de la población) sujetos considerados infectados con dos reacciones serológicas positivas, 49 (66,21%) presentaron CIC en suero, en tanto que en 43 (58,11%) de ellos se encontró cAg por ELISA. Solo en 2 casos serológicamente no reactivos, se detectaron inespecíficamente CIC y cAg. Dentro del grupo considerado no infectado, se observó reactividad inespecífica de bajo título por una de las pruebas serológicas en 16 (11,35%) de 141 individuos. Estos sueros arrojaron resultados consistentemente negativos por ELISA-CIC y cAg demostrando la utilidad de estos métodos de diagnóstico antigénico en casos de serología conflictiva. La determinación de fracciones antigénicas circulantes por ELISA en individuos chagásicos crónicos permite evidenciar la infección por T. cruzi de manera más directa que midiendo la respuesta inmune humoral en el huésped, presentando además mayor sensibilidad que el diagnóstico parasitológico clásico