The tissue specific tropism in Trypanosoma cruzi. Is it true?

Systematic microscopical observations on tissues from mice, inoculated with different Trypanosoma cruzi isolates, were carried out in order to assess whether the parasite expresses tissue-specific tropism, or if it can invade tissues pervasively within the mammal host. A total of ninety mice were included in the study. Sixty, subcutaneously-inoculated with 15 × 10⁴T. cruzi-blood trypomastigotes were dissected and examined daily for detecting and counting parasites during 12 days of acute infection. Additionally, two long-term experiments using mice inoculated with 5 × 10³ metacyclic-forms were performed. A group of 10 mice inoculated intraperitoneally and another group of 20 mice inoculated intradermally. Results demonstrated that T. cruzi does not exhibit a tissue-specific tropism, revealing characteristics of a paninfective species able to invade tissues of ectodermal, mesodermal, and endodermal embryonic origin, irrespective of the parasite's lineage, infective form, route of entry, or size of the inoculum causing the host's infection. Details on T. cruzi-tissue invasion, tissue-parasite load during the course time, and the hypothetical potential pseudocyst/amastigote whole-body burden in the murine model is analyzed. The importance of the findings and its interpretation related to human Chagas disease and the tissue-parasite persistence is also discussed.