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The immunological response during early human Trypanosoma cruzi infection is not completely understood, despite its role in driving the development of distinct clinical manifestations of chronic infection. Herein we report the results of a descriptive flow cytometric immunophenotyping investigation of major and minor peripheral blood leucocyte subpopulations in T. cruzi-infected children, characterizing the early stages of the indeterminate clinical form of Chagas' disease. Our results indicated significant alterations by comparison with uninfected children, including increased values of pre-natural killer (NK)-cells (CD3- CD16+ CD56-), and higher values of proinflammatory monocytes (CD14+ CD16+ HLA-DR++). The higher values of activated B lymphocytes (CD19+ CD23+) contrasted with impaired T cell activation, indicated by lower values of CD4+ CD38+ and CD4+ HLA-DR+ lymphocytes, a lower frequency of CD8+ CD38+ and CD8+ HLA-DR+ cells; a decreased frequency of CD4+ CD25HIGH regulatory T cells was also observed. These findings reinforce the hypothesis that simultaneous activation of innate and adaptive immunity mechanisms in addition to suppression of adaptive cellular immune response occur during early events of Chagas' disease. Comparative cross-sectional analysis of these immunophenotypes with those exhibited by patients with late chronic indeterminate and cardiac forms of disease suggested that a shift toward high values of macrophage-like cells extended to basal levels of proinflammatory monocytes as well as high values of mature NK cells, NKT and regulatory T cells, may account for limited tissue damage during chronic infection favouring the establishment/maintenance of a lifelong indeterminate clinical form of the disease. On the other hand, development of an adaptive cell-mediated inflammatory immunoprofile characterized by high levels of activated CD8+ cells and basal levels of mature NK cells, NKT and CD4+ CD25HIGH cells might lead to late chronic pathologies associated with chagasic heart disease.

Trypanosoma cruzi‐infected children was treated with benznidazole (Bz) during the early‐indeterminate disease (E‐IND) and the cytokine pattern of innate and adaptive immune compartments were evaluated prior to the treatment and 1 year after it. At first, we observed that the ex vivo cytokine profile of circulating leukocytes from E‐IND (n = 6) resembled the one observed for healthy schoolchildren (n = 7). Additionally, in vitro stimulation with T. cruzi antigens drove the E‐IND cytokine pattern toward a mixed immune profile with higher levels of IFN‐γ+, TNF‐α+ and IL‐4+ NK cells, increased numbers of IFN‐γ+, TNF‐α+ and IL‐10+ CD4+ T cells in addition to enhanced frequency of TNF‐α+/IL‐4+ CD19+ lymphocytes. Interestingly, upon T. cruzi antigen in vitro stimulation, E‐IND CD8+ lymphocytes displayed a selective enhancement of IFN‐γ expression, accounting for a global type 1‐modulated cytokine microenvironment. A shift toward a type 1‐modulated profile was also the hallmark of Bz‐treated children (E‐INDT). In this context, despite the mixed overall ex vivo cytokine profile observed for NK and CD8+ T cells, increased ability of these leukocytes to produce IFN‐γ in response to T. cruzi antigens was reported. Most noteworthy was the IL‐10 production evidenced at T lymphocytes, mainly CD4+ cells, as well as B lymphocytes, both ex vivo and upon antigen stimulation. Together, these findings gave evidence that NK cells and CD8+ T lymphocytes are the major sources of IFN‐γ, a pivotal cytokine for successful therapeutic response in human Chagas’ disease. Moreover, our data have also brought additional information, pointing out IL‐10 production by CD4+ cells and B lymphocytes, as the putative key element for parasite clearance in the absence of deleterious tissue damage.

The Caatinga is a semi-arid domain, characterized by reduced humidity and high rates of anthropogenic impact. In addition to the low availability of water, carnivorous mammals are still exposed to a number of threats related to landscape modifications.We used data from camera traps and occupancy models to investigate the habitat use by carnivores in an area of Caatinga in northeastern Brazil. We found a negative correlation between the distance from wind farms and the occupancy probability of the jaguar, and a positive correlation with the occupancy probability of the jaguarundi. Puma and jaguarundi occupied primarily sites near watercourses, whereas the occupancy of the crab-eating fox was correlated positively with the presence of poachers. The ocelot was detected more frequently at sites distant from human settlements, whereas the jaguar was detected more often in areas far from wind farms.We found a negative correlation between the distance of water and the detection of the ocelot. The detection of the crab-eating fox was influenced positively by the detection of cattle. In addition to the negative influence of some anthropic activities, our results indicate that water is a very important resource for species, and the few permanent sources of this resource available in the area must be preserved. The replication of our research in other systems, worldwide, that are experiencing similar pressures, should permit a systematic evaluation of the management and conservation strategies needed to rebuild or maintain populations, restore ecosystems, and support conservation policies in human-altered landscapes.Abstract in Portuguese is available with online material. K E Y W O R D Sbiodiversity, habitat use, human activities, semi-arid environment, wind farm S U PP O RTI N G I N FO R M ATI O NAdditional supporting information may be found online in the Supporting Information section at the end of the article.

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