Examinando por Autor "Medina-Vogel, G."
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Ítem Characterization of Campylobacter spp. isolated from wild birds in the antarctic and Sub-Antarctic(Public Library of Science, 2018-11) Johansson, H.; Ellström, P.; Artursson, K.; Berg, C.; Bonnedahl, J.; Hansson, I.; Hernandez, J.; Lopez-Martín, J.; Medina-Vogel, G.; Moreno, L.; Olsen, B.; Engvall, E.O.; Skarin, H.; Troell, K.; Waldenström, J.; Ågren, J.; González-Acuña, D.A lack of knowledge of naturally occurring pathogens is limiting our ability to use the Antarctic to study the impact human-mediated introduction of infectious microorganisms have on this relatively uncontaminated environment. As no large-scale coordinated effort to remedy this lack of knowledge has taken place, we rely on smaller targeted efforts to both study present microorganisms and monitor the environment for introductions. In one such effort, we isolated Campylobacter species from fecal samples collected from wild birds in the Antarctic Peninsula and the sub-Antarctic island of South Georgia. Indeed, in South Georgia, we found Campylobacter lari and the closely related Campylobacter peloridis, but also distantly related human-associated multilocus sequence types of Campylobacter jejuni. In contrast, in the Antarctic Peninsula, we found C. lari and two closely related species, Campylobacter subantarcticus and Campylobacter volucris, but no signs of human introduction. In fact, our finding of human-associated sequence types of C. jejuni in South Georgia, but not in the Antarctic Peninsula, suggests that efforts to limit the spread of infectious microorganisms to the Antarctic have so far been successful in preventing the introduction of C. jejuni. However, we do not know how it came to South Georgia and whether the same mode of introduction could spread it from there to the Antarctic Peninsula. © 2018 Johansson et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Ítem Ecology and Geography of Transmission of Two Bat-Borne Rabies Lineages in Chile(Public Library of Science (PLoS), 2013) Escobar, L.; Peterson, T.; Favi, M.; Yung, V.; Pons, D.; Medina-Vogel, G.Rabies was known to humans as a disease thousands of years ago. In America, insectivorous bats are natural reservoirs of rabies virus. The bat species Tadarida brasiliensis and Lasiurus cinereus, with their respective, host-specific rabies virus variants AgV4 and AgV6, are the principal rabies reservoirs in Chile. However, little is known about the roles of bat species in the ecology and geographic distribution of the virus. This contribution aims to address a series of questions regarding the ecology of rabies transmission in Chile. Analyzing records from 1985-2011 at the Instituto de Salud Pública de Chile (ISP) and using ecological niche modeling, we address these questions to help in understanding rabies-bat ecological dynamics in South America. We found ecological niche identity between both hosts and both viral variants, indicating that niches of all actors in the system are undifferentiated, although the viruses do not necessarily occupy the full geographic distributions of their hosts. Bat species and rabies viruses share similar niches, and our models had significant predictive power even across unsampled regions; results thus suggest that outbreaks may occur under consistent, stable, and predictable circumstances.Ítem Phylogeography of the Patagonian otter Lontra provocax: Adaptive divergence to marine habitat or signature of southern glacial refugia?(Springer Nature, 2011) Vianna, J.; Medina-Vogel, G.; Chehébar, C.; Sielfeld, W.; Olavarría, C.; Faugeron, S.A number of studies have described the extension of ice cover in western Patagonia during the Last Glacial Maximum, providing evidence of a complete cover of terrestrial habitat from 41°S to 56°S and two main refugia, one in south-eastern Tierra del Fuego and the other north of the Chiloé Island. However, recent evidence of high genetic diversity in Patagonian river species suggests the existence of aquatic refugia in this region. Here, we further test this hypothesis based on phylogeographic inferences from a semi-aquatic species that is a top predator of river and marine fauna, the huillín or Southern river otter (Lontra provocax). Results: We examined mtDNA sequences of the control region, ND5 and Cytochrome-b (2151 bp in total) in 75 samples of L. provocax from 21 locations in river and marine habitats. Phylogenetic analysis illustrates two main divergent clades for L. provocax in continental freshwater habitat. A highly diverse clade was represented by haplotypes from the marine habitat of the Southern Fjords and Channels (SFC) region (43°38' to 53°08'S), whereas only one of these haplotypes was paraphyletic and associated with northern river haplotypes. Conclusions: Our data support the hypothesis of the persistence of L. provocax in western Patagonia, south of the ice sheet limit, during last glacial maximum (41°S latitude). This limit also corresponds to a strong environmental change, which might have spurred L. provocax differentiation between the two environments.Ítem Population assessment and habitat use by marine otter Lontra felina in southern Chile(Nordic Council for Wildlife Research [Client Organisation] Oikos Editorial Office [Associate Organisation], 2006-06) Medina-Vogel, G.; Bartheld, J.; Pacheco, R.; Rodriguez, C.The marine otter Lontra felina lives along the Pacific coast of South America from 6°S to 56°S. A method for estimating marine otter abundance is described and a comparison of the characteristics of the terrestrial habitat of this species in southern Chile is made. From June 1999 to June 2000, we conducted eight hours of observations on one day each month at four study sites. An average of 3.8 observable otters/km were recorded, with significant differences between sites but no systematic trends with regard to season. Observable pups were recorded year-round. Otters spent 80% of their time out of view, engaged in behaviours other than feeding; observable otters were mostly seen feeding. The methodology described is effective for indexing abundances at small geographic scales. The marine otter needs both an aquatic habitat for foraging and a terrestrial habitat with an abundance of safe shelters, which, in turn, could limit the distribution of the species when human settlers and domestic dogs utilise the terrestrial habitats.Ítem Spatial and temporal trends of bat-borne rabies in Chile(Cambridge University Press, 2015-05) Escobar, L.E.; Restif, O.; Yung, V.; Favi, M.; Pons, D.J.; Medina-Vogel, G.In Chile, while dog rabies has decreased markedly over the last 30 years, bat rabies is still reported frequently. In order to shed new light on the spatiotemporal trends of these reports, we analysed active and passive data from years 1985 and 2012, which included 61 076 samples from 289 counties of Chile. We found that from 1994 to 2012, more than 15 000 bat samples were submitted for diagnostics through passive surveillance, 9·5% of which tested positive for rabies. By contrast, the prevalence of infection was only ∼0·4% among the nearly 12 000 bat samples submitted through active surveillance. We found that the prevalence of dog rabies dropped steadily over the same period, with just a single confirmed case since 1998. None of the 928 samples from wild animals, other than bats, were positive for rabies. Although there has been only one confirmed case of human rabies in Chile since 1985, and a single confirmed case in a dog since 1998, bats remain a reservoir for rabies viruses. While active surveillance indicates that rabies prevalence is low in bat colonies, the high proportion of positive bats submitted through passive surveillance is a concern. To prevent human rabies, local public health agencies should increase research on the basic ecology of bats and the role of stray dogs and cats as potential rabies amplifiers. © 2014 Cambridge University Press.Ítem Toxoplasma gondii infection in wild mustelids and cats across an urban-rural gradient(Public Library of Science, 2018-06) Barros, M.; Cabezón, O.; Dubey, J.P.; Almería, S.; Ribas, M.P.; Escobar, L.E.; Ramos, B.; Medina-Vogel, G.The increase in human population and domestic pets, such as cats, are generating important consequences in terms of habitat loss and pathogen pollution of coastal ecosystems with potential to generate negative impacts in marine biodiversity. Toxoplasma gondii is the etiological agent of zoonotic disease toxoplasmosis, and is associated with cat abundance and anthropogenic disturbance. The presence of T. gondii oocysts in the ocean has negatively affected the health status of the threatened Southern sea otter (Enhydra lutris nereis) populations. The present study analyzed seroprevalence and presence of T. gondii DNA in American mink (Neovison vison), Southern river otters (Lontra provocax) and domestic cats (Felis silvestris catus) in four different areas in Southern Chile comprising studies in rivers and lakes in Andean foothills and mountains, marine habitat and island coastal ecosystems. Mean seroprevalence of T. gondii in the study was 64% of 151 total animals sampled: 59% of 73 American mink, 77% of 13 Southern river otters, 68% of 65 domestic cats and in two of two kodkods (Leopardus guigna). Toxoplasma gondii DNA was detected in tissues from one American mink and one Southern river otter. The present study confirms the widespread distribution of T. gondii in Southern Chile, and shows a high exposure of semiaquatic mustelids and domestic cats to the parasite. Cats and anthropogenic disturbance have a role in the maintenance of T. gondii infection in ecosystems of southern Chile. © 2018 Barros et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.