Chagas disease represents one of the major health issue in Latin America. Epidemiological control is focused on disease vectors, so studies on the ecology of triatomine vectors constitute a central strategy. Recently, research at large spatial scale has been produced, and authors commonly rely on the assumption that geographical regions presenting good environmental conditions for most vector species are also those with high risk of infection. In the present work, we provide an explicit evaluation for this assumption. Employing species distribution models and epidemiological data for Chagas disease in Brazilian territory, our results show that species richness is a poor predictor for the observed pattern of Chagas disease occurrence. Species composition proved to be a better predictor. We stress that research on macroecology of infectious diseases should go beyond the analysis of biodiversity patterns and consider human infections as a central part of the focal ecological systems.
Chagas disease is a life-threatening disorder caused by the protozoan parasite Trypanosoma cruzi. Parasite-specific antibodies, CD8+ T cells, as well as IFN-γ and nitric oxide (NO) are key elements of the adaptive and innate immunity against the extracellular and intracellular forms of the parasite. Bim is a potent pro-apoptotic member of the Bcl-2 family implicated in different aspects of the immune regulation, such as negative selection of self-reactive thymocytes and elimination of antigen-specific T cells at the end of an immune response. Interestingly, the role of Bim during infections remains largely unidentified. To explore the role of Bim in Chagas disease, we infected WT, Bim+/−, Bim−/− mice with trypomastigotes forms of the Y strain of T. cruzi. Strikingly, our data revealed that Bim−/− mice exhibit a delay in the development of parasitemia followed by a deficiency in the control of parasite load in the bloodstream and a decreased survival compared to WT and Bim+/− mice. At the peak of parasitemia, peritoneal macrophages of Bim−/− mice exhibit decreased NO production, which correlated with a decrease in the pro-inflammatory Small Peritoneal Macrophage (SPM) subset. A similar reduction in NO secretion, as well as in the pro-inflammatory cytokines IFN-γ and IL-6, was also observed in Bim−/− splenocytes. Moreover, an impaired anti-T. cruzi CD8+ T-cell response was found in Bim−/− mice at this time point. Taken together, our results suggest that these alterations may contribute to the establishment of a delayed yet enlarged parasitic load observed at day 9 after infection of Bim−/− mice and place Bim as an important protein in the control of T. cruzi infections.
This investigation aimed to assess the effect of N-acetylcysteine (NAC) as an adjuvant treatment to alleviate visceral leishmaniasis (VL). The present work includes both blinded randomized clinical intervention and experimental in vitro studies. The clinical trial included 60 patients with VL randomly allocated into two groups: a test group (n = 30) treated with meglumine antimoniate plus NAC (SbV + NAC) and a control group (n = 30) treated with meglumine antimoniate only (SbV). The primary outcome was clinical cure (absence of fever, spleen and liver sizes reduction, and hematological improvement) in 180 days. The cure rate did not differ between the groups; both groups had similar results in all readout indices. The immunological parameters of the patients treated with SbV + NAC showed higher sCD40L in sera during treatment, and the levels of sCD40L were negatively correlated with Interleukin-10 (IL-10) serum levels. In addition, data estimation showed a negative correlation between the sCD40L levels and the spleen size in patients with VL. For the in vitro experiments, peripheral blood mononuclear cells (PBMCs) or PBMC-derived macrophages from healthy donors were exposed to soluble Leishmania antigen (SLA) or infected with stationary promastigotes of Leishmania infantum in the presence or absence of NAC. Results revealed that NAC treatment of SLA-stimulated PBMCs reduces the frequency of monocytes producing IL-10 and lowers the frequency of CD4+ and CD8+ T cells expressing (pro-)inflammatory cytokines. Together, these results suggest that NAC treatment may modulate the immune response in patients with VL, thus warranting additional investigations to support its case use as an adjuvant to antimony therapy for VL.
Estudos anteriores sobre a doença de Chagas em grandes escalas espaciais não exploraram como a interação com humanos pode afetar as projeções para a distribuição geográfica da aptidão ambiental das espécies de vetores. Aqui, comparamos modelos de distribuição de espécies usando apenas variáveis climáticas como preditores (SDMClim) com modelos que incluem variáveis climáticas + densidade populacional humana (SDMHuman). Nossos resultados mostram que considerar a densidade da população humana ajuda a refinar os modelos para escalas geográficas mais finas. Além disso, diferentes padrões espaciais de adequabilidade ambiental acumulada foram obtidos por SDMClim e SDMHuman. Ainda, as projeções foram mais precisas para SDMHuman do que para SDMClim. Nossos resultados mostram que considerar fatores antropogênicos em SDMs para espécies de triatomianos epidemiologicamente relevantes pode melhorar nossa compreensão da macroecologia e biogeografia para vetores da doença de Chagas.
Objectives: to estimate the detection rate on prenatal screening pathologies on paper filter in the South and Southwest in the State of Bahia, as well as to delineate the epidemiological profile of these pregnant women, calculate and estimate the rate of adherence and the coverage of the Program. Methods: a descriptive study was carried out from August 2013 to August 2015, and the data were obtained from the Labimuno/ICS/UFBA. Results: 64,743 pregnant women were included; the mean ages were 25 years for the Southwest macro-region and 23 for the South. The results on the screening tests showed positivity of 0.13% and 0.29% for HBsAg, 0.17% and 0.22% for cytomegalovirus, 0.07% and 0.09% for HCV, 0.13% and 0.38% for HTLV, 0.04% and 0.19% for HIV, 1.2% and 2.84% for syphilis, and 0.54% and 0.73% for toxoplasmosis in the Southwest and South macro-regions, respectively. The estimates on coverage were considered satisfactory. Sickle cell anemia showed positivity of 0.02% and of 0.04% and 5% and 6.3% presented sickle cell trait in the Southwest and South macro-regions, respectively. Conclusions: the frequencies of infections in maternal-fetal health were considered low, highlighting on syphilis and the presence for sickle cell trait.
People living in endemic areas of Chagas disease are submitted to multiple infections during their lives. This is an important factor in the development and morbidity of the disease. In the present investigation, evaluate the treatment outcome of triple infection mice with 21SF clones compared to the parental strain and with clones were investigated. Mice were infected and divided into groups: G1, infected with 21SF strain; G2, infected with 3 clones of the 21SF strain; and G3, infected with each clone alone. Subsequently, the groups were subdivided in treated and untreated controls. After the treatment the mice were euthanized. Serological tests and parasitological tests were performed. Sections of the heart and skeletal muscle were collected, fixed and then processed for the histopathological study in sections stained with Hematoxilin end Eosin. Parasitological tests for animals treated have shown positive results that varied from 25 to 66.7% and the serology titers varied from 1:10 a 1:280 in treated mice. Cure rates ranged from 11.1 to 30.8%. Histopathological examination revealed that treated animals presented clear reduction of lesions in myocardium and in skeletal muscle. Animals subjected to multiple infections have low rates of cure and worsening of tissue lesions.
Previous work on Chagas Disease disease at large spatial scales has not explored how interaction with humans can affect projections for geographical distribution of environmental suitability of vector species. Here, we compare niche-based species distribution models with climatic variables as predictors (SDM clim ) and with climatic variables + human population density (SDM Human ). Our results show that accounting for human population density helps refine the models to finer geographical scales. Also, different spatial patterns of accumulated environmental suitability were obtained by SDM clim and SDM Human . Moreover, projections were more accurate for SDM Human than for SDM clim . Our results show that considering human populations in SDMs for epidemiologically relevant triatomiane species can improve our understanding of macroecology and biogeography of environmental suitability for vectors of Chagas disease.
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