Detecting Acute Stages

In endemic areas of Chagas’ disease it is important to detect acute and even asymptomatic infections in children so that specific therapy can be started immediately. Serologic profiles of eighty‑six chagasic children and fifty‑six healthy children from a highly endemic area in Cochabamba, Bolivia, indicate that alpha‑2‑macroglobulin (A2M) and C‑reactive protein (CRP) were significantly increased in acute chagasic children (MedranoMercado et al. 1996). Because parasites are commonly present in blood and tissues during the acute phase, it is possible that the high levels of A2M may act as inhibitors of a high level of proteinases, derived from the parasites, from host cell damage, or from both. These results open a route to discern different stages in the acute infection by examination of sera and using humoral criteria:

1) an early acute stage, with an increase only in specific anti‑T. cruzi immunoglobulin M (IgM) levels (group 1);

2) an intermediate acute stage having high specific IgM levels and/or high immunoglobulin G (IgG) levels and/or high anti‑galactose (anti‑Gal) levels and increased A2M and/or CRP levels;

3) a late acute stage, with low IgM levels but high A2M, CRP, anti‑Gal, and specific IgG levels.

The detection of high immunoglobulin G alone is indicative of the chronic/indeterminate stage of Chagas’ disease (Medrano‑Mercado et al. 1996).

In Bolivia, however, serological methods involve many problems, including difficulties in sample collection and storage until the time of screening; difficulties in the standardization of the diagnostic methods commonly used, such as the indirect hemagglutination test, the indirect immunofluorescence test, ELISA, or complement fixation; and the absence of a clear correlation of the results of tests performed in different laboratories (Pless et al. 1992). The procedures and techniques to quantify five relevant proteins are easy to perform and to automate for large‑scale screening, in contrast to other immunologic techniques that are used for serodiagnosis of Chagas’ disease. They would consititute a tool in detecting acute Chagas’ disease, especially in endemic rural areas.