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

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. cruzi Y or Berenice-78 strains. In vitro infectivity of Vero cells as well as the extension of cardiac lesions in infected Beagle was higher for Y strain when compared to Berenice-78 strain. These data suggested that in vitro infectivity assays may correlate with pathogenicity in vivo. In fact, animals infected with Y strain, which shows prevalence of slender forms and high infectivity in vitro, presented cardiomegaly, inflammation, and fibrosis in heart area. Concerning the immunoglobulin production, no statistically significant difference was observed for IgA, IgM or IgG levels among T. cruzi infected animals. However, IgA together IgM levels have shown to be a good marker for the acute phase of Chagas disease.

Estudo quantitativo e qualitativo dos plexos de Auerbach e Meissner do esôfago de cäes inoculados com o Trypanosoma cruzi / A quantitative and qualitative study of the Auerbach and Meissner plexus in dogs inoculated with Trypanosoma cruzi

A quantitative and qualitative study was conducted on the Auerbach and Meissner plexuses of the esophagus of four chagasic dogs sacrificed during the acute phase of infection. Ganglionitis and periganglionitis of the Auerbach plexus ranged from mild to moderate and induced significant neuronal lesions, especially in two animals. The ganglions of the Meissner plexus were observed in small number which did not permit any analysis. Mild or moderate myositis was observed mainly in the lower third of the esophagus and was rarely associated with amastigote nests. Ganglion and neuron counts did not demonstrate denervation. Although the formation of megaesophagus was not induced in any dog, lesions of the Auerbach plexus and myocells of the esophagus were observed during the acute phase of chagasic infection. To our knowledge, this is the first systematic quantitative and qualitative study of the Auerbach and Meissner plexuses of the esophagus in experimental trypanosomiasis cruzi.

Cardiac plexus of dogs experimentally infected with Trypanosoma cruzi: inflammatory lesions and quantitative studies

Qualitative and quantitative aspects of the superficial and profound cardiac plexus of dogs experimentally infected with Be-62 and Be-78 strains of Trypanosoma cruzi were studied. Animals were autopsied in the acute phase ofinfection. The inflammatory process, lesions and number of parasites were more intense and frequent in animals infected with the Be-78 strain than in those infected with Be-62. espite this, no statistically significant differences could be found between the number of neuron bodies in the ganglia of infected and control dogs.