ABSTRACT Climate change affects the dynamics of vector-borne diseases. Culex pipiens Linnaeus is the main vector of West Nile fever; a widely distributed arbovirus, it is continuously increasing its distribution. Using a species distribution model, maps of suitable habitats of Cx. pipiens were generated for Chile in the current climate and three climate change scenarios, using global and regional georeferenced vector presence records as input, plus bioclimatic variables. Since this virus has not yet arrived in Chile, the purpose of this study is to anticipate potential risk areas and to prevent the establishment and spread of the virus. Cx. pipiens is widely distributed in Chile. The suitable habitats in Chile were concentrated mostly from 32º to 35ºS, increasing in future scenarios up to 113 % in the northern zone and moving towards the mountains. This species conserves around 90 % of its niche in the future, and shows a reduction of 11.4 % in the severe climate change scenario. It is anticipated that Chile will experience an increase in the environmental suitability for Cx. pipiens moving from the Andes to the coastal zone throughout the country, mainly in the center-south. This will raise the risk of local virus transmission if the virus is introduced to the country via diverse routes.

RESUMEN El cambio climático afecta la dinámica de las enfermedades transmitidas por vectores. Culex pipiens Linnaeus es el vector principal de la fiebre del Nilo Occidental, un arbovirus que aumenta continuamente su distribución. Usando un modelo de distribución de especies, se generaron mapas hábitats favorables para Cx. pipiens en los escenarios de cambio climático actuales y tres futuros. Se utilizaron registros de presencia de vectores georreferenciados globales y regionales como entrada, más un conjunto de variables bioclimáticas. Dado que este virus aún no ha llegado a Chile, el propósito de este estudio es anticipar áreas de riesgo potencial y prevenir el establecimiento y la propagación del virus. Cx. pipiens está ampliamente distribuido en Chile. Las mayores probabilidades de presencia en Chile se concentraron principalmente de 32º a 35ºS, aumentando en escenarios futuros hasta el 113 % en la zona norte y avanzando hacia la cordillera. Esta especie conserva alrededor del 90 % de su nicho en el futuro y muestra una reducción del 11,4 % en el escenario de cambio climático severo. Se propone que Chile experimentará un aumento en los hábitats favorables para Cx. pipiens, el vector clave del WNV, que se moverá desde los Andes a la zona costera en todo el país, principalmente en el centro-sur. Esto producirá un aumento en el riesgo de transmisión del virus local si se introduce en el país a través de diversas rutas.

BACKGROUND Vector transmission of Trypanosoma cruzi appears to be interrupted in Chile; however, data show increasing incidence of Chagas' disease, raising concerns that there may be a reemerging problem. OBJECTIVE To estimate the actual risk in a changing world it is necessary to consider the historical vector distribution and correlate this distribution with the presence of cases and climate change. METHODS Potential distribution models of Triatoma infestans and Chagas disease were performed using Maxent, a machine-learning method. FINDINGS Climate change appears to play a major role in the reemergence of Chagas' disease and T. infestans in Chile. The distribution of both T. infestans and Chagas' disease correlated with maximum temperature, and the precipitation during the driest month. The overlap of Chagas' disease and T. infestans distribution areas was high. The distribution of T. infestans, under two global change scenarios, showed a minimal reduction tendency in suitable areas. MAIN CONCLUSION The impact of temperature and precipitation on the distribution of T. infestans, as shown by the models, indicates the need for aggressive control efforts; the current control measures, including T. infestans control campaigns, should be maintained with the same intensity as they have at present, avoiding sylvatic foci, intrusions, and recolonisation of human dwellings.

In this contribution we studied the developmental phenotypic plasticity of respiratory structures involved in the exchange of gases in an altricial rodent, the leaf-eared mouse {Phyllotis darwini). We studied morphological pulmonary parameters of warm (30 °C) and cold acclimated animals 15 °C) at different developmental stages. We found that acclimation treatments did not affect neither lung volume, the alveolo-capillary barrier thickness nor the respiratory surface density. In consequence the oxygen diffusion capacity was not affected. Although Phyllotis darwini exhibited structural respiratory changes expected by its ontogenetic development, these structures were not affected by thermal acclimation during the post-natal development.

Estudiamos la plasticidad fenotípica del desarrollo de las estructuras respiratorias responsables del intercambio de oxígeno en el roedor altricial Phyllotis darwini. Investigamos los parámetros morfológicos del pulmón en animales aclimatados a alta temperatura (bajo requerimiento energético de termorregulación: 30 °C) y a baja temperatura (alto requerimiento: 15 °C) en diferentes etapas del desarrollo. Encontramos que la temperatura ambiental no afectó el volumen pulmonar, el grosor de la barrera alvéolo-capilar ni la densidad de superficie alveolar. Y en consecuencia, tampoco la capacidad de difusión de oxígeno. Aun cuando Phyllotis darwini mostró los cambios respiratorios esperados de acuerdo a su desarrollo ontogénico, las estructuras evaluadas no fueron afectadas por la aclimatación térmica durante el desarrollo postnatal.