The influence of lymphatic drainage in experimental Trypanosoma cruzi infection

The rapid disappearance of infective forms of Trypanosoma cruzi from the site of inoculation as well as the initial phase of infection produced by the parasite are not yet fully understood. To investigate this problem we used the hamster as an animal model considering the existence of the cheek pouch--a peculiar region devoid of lymphatic vessels. T. cruzi trypomastigotes were inoculated into the cheek pouch or into the footpad of animals previously infected or not with the same parasite. The results were followed from 3 up to 21 days postinoculation, by histological examination. In the cheek pouch of normal animals a large number of parasites could be seen up to 15 days post-inoculation and the inflammatory infiltrate had a focal distribution. Conversely, in the footpad the infiltrate was diffuse and no parasites could be detected. These observations indicate that the lymphatic system is the main route of T. cruzi dissemination from the site or inoculation. When hamsters were first inoculated in the footpad and 7 days later in the pouch, the inflammatory infiltrate at this point was less aggressive and no parasites could be detected.