Dogs infected with the blood trypomastigote form of Trypanosoma cruzi display an increase expression of cytokines and chemokines plus an intense cardiac parasitism during acute infection.

The recent increase in immigration of people from areas endemic for Chagas disease (Trypanosoma cruzi) to the United States and Europe has raised concerns about the transmission via blood transfusion and organ transplants in these countries. Infection by these pathways occurs through blood trypomastigotes (BT), and these forms of T. cruzi are completely distinct of metacyclic trypomastigotes (MT), released by triatomine vector, in relation to parasite-host interaction.

Development of chronic cardiomyopathy in canine Chagas disease correlates with high IFN-gamma, TNF-alpha, and low IL-10 production during the acute infection phase.

When infected with Trypanosoma cruzi, Beagle dogs develop symptoms similar to those of Chagas disease in human beings, and could be an important experimental model for a better understanding of the immunopathogenic mechanisms involved in chronic chagasic infection. This study evaluates IL-10, IFN-gamma and TNF-alpha production in the sera, culture supernatant, heart and cervical lymph nodes and their correlation with cardiomegaly, cardiac inflammation and fibrosis in Beagle dogs infected with T. cruzi.

Trypanosoma cruzi: Serum levels of nitric oxide and expression of inducible nitric oxide synthase in myocardium and spleen of dogs in the acute stage of infection with metacyclic or blood trypomastigotes.

The participation of nitric oxide (NO) in the control of blood parasitemia and parasitism during the acute phase of infection in dogs inoculated with blood trypomastigotes (BT) or metacyclic trypomastigotes (MT group) of Berenice-78 Trypanosoma cruzi strain has been evaluated. Animals of the MT group (n=4) presented increased levels of serum NO throughout the infection when compared with the BT (n=4) or control (n=4) groups, and a delay in parasitemia peak compared with the BT group. In spleen fragments, tissue parasitism was not observed but the MT group presented larger areas associated with inducible NO synthase (iNOS) in relation to BT and control groups.

Trypanosoma cruzi high infectivity in vitro is related to cardiac lesions during long-term infection in Beagle dogs.

Trypanosoma cruzi is a hemoflagelate parasite associated with heart dysfunctions causing serious problems in Central and South America. Beagle dogs develop the symptoms of Chagas disease in humans, and could be an important experimental model for better understanding the immunopathogenic mechanisms involved in the chagasic infection. In the present study we investigated the relation among biological factors inherent to the parasite (trypomastigote polymorphism and in vitro infectivity) and immunoglobulin production, inflammation, and fibrosis in the heart of Beagle dogs infected with either T.