FIG 3.

Curative benznidazole treatment of C3H/HeN mice infected with T. cruzi strain JR prevents the development of cardiac fibrosis. Infected mice (see Materials and Methods) were either nontreated (NT; n = 24), or treated (T) with benznidazole for 20 days, as outlined in the legend to Fig. 1, commencing day 14 postinfection (n = 10), or day 73 (n = 12). Groups of noninfected mice, either nontreated (NT; n = 16), or treated (T) (starting on day 14, n = 8, or on day 73, n = 8) were run in parallel. Cardiac tissue was harvested (day 150 to 153) and assessed for inflammation and fibrosis (see Materials and Methods). (A) Quantitative histopathological analysis of inflammation. The number of nuclei per 6 × 10⁴ μm² was quantified as a cellular myocarditis index. Data are shown as mean ± standard deviation. Inflammation in nontreated infected mice was slightly but significantly greater than that in noninfected controls or in drug cured mice. (B) Representative myocardial sections stained with H&E and used to assess inflammation. (C) Quantification of collagen content (blue area in Masson's trichrome-stained sections) as a marker of cardiac fibrosis (see the text for more details and Materials and Methods for description of statistical procedures). (D) Masson's trichrome-stained photomicrographs demonstrating fibrosis in mice heart sections. In panels B and D, the magnification is 400×. Bar, 30 μm.