[Highly homogeneous Trypanosoma cruzi populations in a low endemic region for Chagas disease: importance in the pathogenesis of Chagas disease in Chile].

Trypanosoma cruzi from 23 chronic and acute cases of Chagas disease were isolated and further characterized. They displayed a remarkable similarity, after typification by schizodeme analysis using restriction endonuclease Eco Ri. All T cruzi isolates belonged to the isoenzymatic Zymodeme 2 Bol. These findings were corroborated analyzing cases from families with demonstrated congenital transmission. The acute cases were newborns or offspring of infected mothers or patients with AIDS. All T cruzi strains isolated in these cases were very similar with almost identical schizodemes. Patients with AIDS had severe clinical manifestations whereas children with congenital infections had a great variety of clinical symptoms. In chronic cases, little clinical differences were observed for the different T cruzi strains. It is concluded that there is a low correlation between the T cruzi strain and the clinical prognosis of Chagas disease, being of greater relevance the host's genetic background and immune response.