Highly diluted medication reduces parasitemia and improves experimental infection evolution by Trypanosoma cruzi

BACKGROUND: There is no published information about the use of different protocols to administer a highly diluted medication. Evaluate the effect of different protocols for treatment with biotherapic T. cruzi 17 dH (BIOT(Tc17dH)) on clinical/parasitological evolution of mice infected with T. cruzi-Y strain. METHODS: A blind, randomized controlled trial was performed twice, using 60 28-day-old male Swiss mice infected with T. cruzi-Y strain, in five treatment groups: CI - treated with a 7% ethanol-water solution, diluted in water (10 μL/mL) ad libitum; BIOT(PI) - treated with BIOT(Tc17dH) in water (10 μL/mL) ad libitum during a period that started on the day of infection; BIOT(4DI) - treated with BIOT(Tc17dH) in water (10 μL/mL) ad libitum beginning on the 4(th) day of infection; BIOT(4-5–6) - treated with BIOT(Tc17dH) by gavage (0.2 mL/ animal/day) on the 4(th), 5(th) and 6(th) days after infection; BIOT(7-8–9) - treated with BIOT(Tc17dH) by gavage (0.2 mL/ animal/day) on the 7(th), 8(th) and 9(th) days after infection. We evaluated: parasitemia; total parasitemia (P(total)); maximum peak of parasites; prepatent period (PPP) - time from infection to detection of the parasite in blood; patent period (PP) - period when the parasitemia can be detected in blood; clinical aspects; and mortality. RESULTS: Parasitological parameters in the BIOT(PI) and mainly in the BIOT(4PI) group showed better evolution of the infection compared to the control group (CI), with lower P(total), lower maximum peak of parasites, higher PPP, lower PP and longer survival times. These animals showed stable body temperature and higher weight gain and water consumption, with more animals having normal-appearing fur for longer periods. In contrast, groups BIOT(4-5–6) and BIOT(7-8–9) showed worse evolution of the infection compared to the control group, considering both parasitological and clinical parameters. The correlation analysis combined with the other data from this study indicated that the prepatent period is the best parameter to evaluate the effect of a medication in this model. CONCLUSIONS: The BIOT(4DI) group showed the best clinical and parasitological evolution, with lower parasitemia and a trend toward lower mortality and a longer survival period. The prepatent period was the best parameter to evaluate the effect of a medication in this model.