Eco-Epidemiology of Chagas Disease in Chile

There are four vector species of Chagas disease in Chile: Triatoma infestans, responsible for the domestic cycle; Mepraia spinolai, the main wild vector; and M. gajardoi and M. parapatrica, two coastal wild species whose importance as vectors is not well known. They are species of dry environments of the central-north region of Chile, whose best predictors of distribution are warm average temperatures and low rainfall. They are found in rock quarries, nests of birds, and small mammals, and T. infestans has sylvatic foci associated with a Bromeliaceae species. While human blood represents 70% of the diet of T. infestans, in M. spinolai this value is 7%, which means that a large part of Chagas disease in Chile is due to T. infestans. However, all species have high percentages of T. cruzi infection. Chagas disease in Chile follows the distribution of T. infestans, and although the cycle of domestic transmission by this vector is interrupted, there is still a constant prevalence and mortality and ascending incidences. Models predict that although climate change will not vary greatly the north-south distribution of vectors, it could increase the reproductive number of the disease, increasing risk areas of Chagas disease

Thermal ecology of small animals

One of the most representative cases in which the relation individual-environment is evident is the heat exchange between animals and their physical environment. Based on the physical laws regulating heat exchange and on the geometrical relationships between areas and volumes, I show in this articles some strategies for avoiding heat loss used by small animals. The article is organized in four sections. The introduction deals with the laws of radiation, conduction, convection and evaporation, and how they constraint the strategies for avoiding heat loss. Next, how these strategies are related to the larger area of small animals (with regard to their volume). The remaining sections refer to some aspects of the thermal ecology of both exothermic and endothermic animals, based on Chilean examples. Emphasis is place on the responses to heat exhibited by bugs (exothermic animals), which may select substrate temperatures and use the thermal key for host attraction, and on the huddling behav

Development and population parameters of cohorts of the chilean recluse spider Loxosceles laeta Desarrollo de cohortes y parámetros poblacionales de la araña del rincón Loxosceles laeta

© 2014 Sociedad Chilena de Infectologia. All rights reserved.Background: Despite the abundant eco-epidemiological knowledge of the Chilean reclusive spider, Loxosceles laeta, which causes all forms of loxoscelism in Chile, the main characteristics of this species its stages of development remains poorly known especially in the medical area. Objective: In this study we address these issues with the goal of providing clear images of the development of this species and for the first time on population projections as well as the relationship between mature and immature instars, useful data for the control and prevention of accidental bites. Results: We found that L. laeta is an r-selected species, with R0= 2.1, a generation time of G = 2.1 years, with a concentration of the reproductive value of females between the first and second year of life. We determined the average sizes and development times of all instars. The first vary between 2.3 mm at birth and about 13 mm at adulthood. The to

Development and population parameters of cohorts of the chilean recluse spider Loxosceles laeta Desarrollo de cohortes y parámetros poblacionales de la araña del rincón Loxosceles laeta

© 2014 Sociedad Chilena de Infectologia. All rights reserved.Background: Despite the abundant eco-epidemiological knowledge of the Chilean reclusive spider, Loxosceles laeta, which causes all forms of loxoscelism in Chile, the main characteristics of this species its stages of development remains poorly known especially in the medical area. Objective: In this study we address these issues with the goal of providing clear images of the development of this species and for the first time on population projections as well as the relationship between mature and immature instars, useful data for the control and prevention of accidental bites. Results: We found that L. laeta is an r-selected species, with R0= 2.1, a generation time of G = 2.1 years, with a concentration of the reproductive value of females between the first and second year of life. We determined the average sizes and development times of all instars. The first vary between 2.3 mm at birth and about 13 mm at adulthood. The to

Effect of Colony, Patch Distance, And Trajectory Sense on Movement Complexity in Foraging Ants

Artículo de publicación ISIAnimals display foraging trajectories when exploiting food patches. These displacements have been studied, particularly in organisms that forage from a central place. The complexity of a movement path may be analyzed by means of the fractal dimension, an index that estimates the tortuosity of a trajectory. In field experiments we studied the effect of trajectory sense, distance to the resource patch and colony on the movement complexity in a common ant of central Chile. We found that these factors and their interactions significantly affected the complexity of movement paths. We discuss whether mortality risk determines more linear trajectories when the resource patch is distant from the nest, and whether the information acquired from the environment by workers determines less complex return trips.This work was financed by grants PG/15/2000 (Depto. Postgrado y Postítulo, Universidad de Chile) and FONDECYT 2010001 to H T-C

Respiratory refinements in the mygalomorph spider Grammostola rosea Walckenaer 1837 (Araneae, Theraphosidae)

In this study we hypothesized that Grammostola rosea Walckenaer 1837, an active predator of large size that depends on its two paired book lungs for respiration, would have a refined low energy strategy based on its thin air-hemolymph barrier. The morphology of book lungs and the oxygen consumption at 20° and 30°C under normal and starvation conditions were studied. The oxygen consumption was low compared to that expected for spiders from the allometric relationship, 0.027 ± 0.01 ml O2 g-1 h-1 (average ± standard deviation), and it was depressed at 30°C under starvation. The harmonic mean thickness of the air-hemolymph barrier was 0.14 ± 0.03 μm, the respiratory surface density was 122.99 ± 35.84 mm-1, and the book lung volume ranged from 12.2 to 37.5 mm3. With these parameters a high oxygen diffusion capacity was estimated. The combination of low resting oxygen consumption and high pulmonary oxygen conductance results in very low gradients of partial oxygen pressures across the air-h

Pneumonia in the inmunocompromised host: Perspective through images diagnosis and a Bayesian inference Neumonías en el inmunocomprometido: Perspectiva desde el diagnóstico por imágenes, e inferencia Bayesiana

Introduction: The population of immunocompromised patients has increased in recent decades. Many of these patients eventually present infectious complications including pneumonia, which is a diagnostic that must to be prompt and accurate. Objective: To review the basis of the diagnosis of pneumonia in the immunocompromised patient. Sorted by the methodology of Bayesian inference, very relevant in the diagnostic attribution, we review the main basis of the diagnosis of pneumonia of immunocompromised patients: the epidemiology, the clinical history including the type of immunosuppression that weigh the likelihood of attribution a priori of an etiologic agent, and finally, the findings in the image (or likelihood function). Conclusion: Although in general the findings are not pathognomonic and there is much overlap in the images, there are several features that orient in one direction or another. Proper assessment of the prior probability and the likelihood function is allowing ultimatel