Transmission potential, skin inflammatory response, and parasitism of symptomatic and asymptomatic dogs with visceral leishmaniasis

<p>Abstract</p> <p>Background</p> <p>Visceral leishmaniasis in Brazil is caused by the protozoan <it>Leishmania (Leishmania) chagasi </it>and it is transmitted by sandfly of the genus <it>Lutzomyia</it>. Dogs are an important domestic reservoir, and control of the transmission of visceral leishmaniasis (VL) to humans includes the elimination of infected dogs. However, though dogs are considered to be an important element in the transmission cycle of <it>Leishmania</it>, the identification of infected dogs representing an immediate risk for transmission has not been properly evaluated. Since it is not possible to treat infected dogs, they are sacrificed when a diagnosis of VL is established, a measure that is difficult to accomplish in highly endemic areas. In such areas, parameters that allow for easy identification of reservoirs that represents an immediate risk for transmission is of great importance for the control of VL transmission. In this study we aimed to identify clinical parameters, reinforced by pathological parameters that characterize dogs with potential to transmit the parasite to the vector.</p> <p>Results</p> <p>The major clinical manifestations of visceral leishmaniasis in dogs from an endemic area were onicogriphosis, skin lesions, conjunctivitis, lymphadenopathy, and weight loss. The transmission potential of these dogs was assessed by xenodiagnosis using <it>Lutzomyia longipalpis</it>. Six of nine symptomatic dogs were infective to <it>Lutzomyia longipalpis </it>while none of the five asymptomatic dogs were infective to the sandfly. <it>Leishmania </it>amastigotes were present in the skin of all clinically symptomatic dogs, but absent in asymptomatic dogs. Higher parasite loads were observed in the ear and ungueal region, and lower in abdomen. The inflammatory infiltrate was more intense in the ears and ungueal regions of both symptomatic and asymptomatic dogs. In clinically affected dogs in which few or none <it>Leishmania </it>amastigotes were observed, the inflammatory infiltrate was constituted mainly of lymphocytes and macrophages. When many parasites were present, the infiltrate was also comprised of lymphocytes and macrophages, as well as a larger quantity of polymorphonuclear neutrophils (PMNs).</p> <p>Conclusion</p> <p>Dogs that represent an immediate risk for transmission of <it>Leishmania </it>in endemic areas present clinical manifestations that include onicogriphosis, skin lesions, conjunctivitis, lymphadenopathy, and weight loss. Lymphadenopathy in particular was a positive clinical hallmark since it was closely related to the positive xenodiagnosis.</p

A study on the immunological basis of the dissociation between type I-hypersensitivity skin reactions to Blomia tropicalis antigens and serum anti-B. tropicalis IgE antibodies

<p>Abstract</p> <p>Background</p> <p>Two conditions are used as markers of atopy: the presence of circulating anti-allergen IgE antibodies and the presence of positive skin prick test (SPT) reactions to allergenic extracts. The correlation between these conditions is not absolute. This study aimed at investigating immunological parameters that may mediate this lack of correlation. Individuals whose sera contained anti-<it>B. tropicalis </it>extract IgE antibodies (α<it>-Bt</it>E IgE) were divided into two groups, according to the presence or absence of skin reactivity to <it>B. tropicalis </it>extract (<it>Bt</it>E). The following parameters were investigated: total IgE levels; α<it>-Bt</it>E IgE levels; an arbitrary α<it>-Bt</it>E IgE/total IgE ratio; the proportion of carbohydrate-reactive α<it>-Bt</it>E IgE; the proportion of α<it>-Bt</it>E IgE that reacted with <it>Ascaris lumbricoides </it>extract (<it>Al</it>E); the production of IL-10 by <it>Bt</it>E- and <it>Al</it>E-stimulated peripheral blood cells (PBMC).</p> <p>Results</p> <p>Total IgE levels were similar in the two groups, but α<it>-Bt</it>E IgE was significantly higher in the SPT-positive group (SPT<b>+</b>). A large overlap of α<it>-Bt</it>E IgE levels was found in individuals of both groups, indicating that these levels alone cannot account for the differences in SPT outcome. Individuals of the two groups did not differ, statistically, in the proportion of α-<it>Bt</it>E IgE that reacted with carbohydrate and in the production of IL-10 by <it>Bt</it>E- and <it>Al</it>E-stimulated PBMC. Both groups had part of α-<it>Bt</it>E IgE activity absorbed out by <it>Al</it>E, indicating the existence of cross-reactive IgE antibodies. However, the α-<it>Bt</it>E IgE from the SPT-negative individuals (SPT-) was more absorbed with <it>AlE </it>than the α-<it>Bt</it>E IgE from the SPT+ individuals. This finding may be ascribed to avidity differences of the α-<it>Bt</it>E IgE that is present in the two groups of individuals, and could occur if at least part of the α-<it>Bt</it>E IgE from the SPT- individuals were elicited by <it>A. lumbricoides </it>infection.</p> <p>Conclusion</p> <p>The present results suggest that a low ratio of specific IgE to total IgE levels (in a minority of individuals), and differences in α-<it>Bt</it>E IgE avidities (which would have high affinities for <it>A. lumbricoides </it>antigens in SPT- than in SPT<b>+ </b>individuals) may play a role in the down-modulation of type-I hypersensitivity reaction against aeroallergens described in helminth-infected individuals.</p

Dietary Habits And Functional Limitation Of Older Brazilian Adults: Evidence From The Brazilian National Health Survey (2013)

OBJECTIVE: To compare the consumption of selected healthy and unhealthy food groups among elderly Brazilians with daily living activity limitations relative to those with no limitations. DESIGN: Cross-sectional analyses of a nationally representative survey. Setting: The Brazilian National Health Survey, conducted in 2013. SUBJECTS: 11,177 Brazilians aged 60 and over. RESULTS: The prevalence of daily living limitations was 29% (95% CI 27.6,30.5). The consumption of daily meat, beans on a regular basis, and recommended fruit and vegetables intake were 67.1% (95% CI 66.5,68.7), 71.3% (95% CI 69.9,72.8) and 37.3% (95% CI 35.6,39.9), respectively. Compared to those without functional limitation, the consumption of these three food groups was significantly lower among those older adults with functional limitation (Prevalence Ratio = 0.89, 95% CI 0.80,0.98; 0.90, 95% CI 0.82,0.99 and PR 0.86, 95% CI, 0.76,0.96, respectively), independently of age, sex, marital status, living arrangements and education. Level of education showed a strong positive association with fruit and vegetable consumption, and a negative association with bean consumption, a staple diet in Brazil. CONCLUSIONS: Our findings highlight the need for public health policies to increase consumption healthy food consumption among those older adults with functional limitations, especially fruit and vegetable intake among those who have low education levels

Identification and functional characterization of a novel arginine/ornithine transporter, a member of a cationic amino acid transporter subfamily in the Trypanosoma cruzi genome

Background: Trypanosoma cruzi, the etiological agent of Chagas disease, is auxotrophic for arginine. It obtains this amino acid from the host through transporters expressed on the plasma membrane and on the membranes of intracellular compartments. A few cationic amino acid transporters have been characterized at the molecular level, such as the novel intracellular arginine/ornithine transporter, TcCAT1.1, a member of the TcCAT subfamily that is composed of four almost identical open reading frames in the T. cruzi genome. Methods: The functional characterization of the TcCAT1.1 isoform was performed in two heterologous expression systems. TcCAT subfamily expression was evaluated by real-time PCR in polysomal RNA fractions, and the cellular localization of TcCAT1.1 fused to EGFP was performed by confocal and immunoelectron microscopy. Results: In the S. cerevisiae expression system, TcCAT1.1 showed high affinity for arginine (Km = 0.085 ± 0.04 mM) and low affinity for ornithine (Km = 1.7 ± 0.2 mM). Xenopus laevis oocytes expressing TcCAT1.1 showed a 7-fold increase in arginine uptake when they were pre-loaded with arginine, indicating that transport is enhanced by substrates on the trans side of the membrane (trans-stimulation). Oocytes that were pre-loaded with [3H]-arginine displayed a 16-fold higher efflux of [3H]-arginine compared with that of the control. Analysis of polysomal RNA fractions demonstrated that the expression of members of the arginine transporter TcCAT subfamily is upregulated under nutritional stress and that this upregulation precedes metacyclogenesis. To investigate the cellular localization of the transporter, EGFP was fused to TcCAT1.1, and fluorescence microscopy and immunocytochemistry revealed the intracellular labeling of vesicles in the anterior region, in a network of tubules and vesicles. Conclusions: TcCAT1.1 is a novel arginine/ornithine transporter, an exchanger expressed in intracellular compartments that is physiologically involved in arginine homeostasis throughout the T. cruzi life cycle. The properties and estimated kinetic parameters of TcCAT1.1 can be extended to other members of the TcCAT subfamily