Navegando por Autor "Abrahão, Carlos R."

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Artigo
Density matters
(ResearchGate, 2024) Moinet, Marie; Abrahão, Carlos R.; Gasparotto, Vinícius P. O.; Wilkinson, David A.; Vallée, Emilie; Benschop, Jackie; Russell, James C.
Rodents are maintenance hosts of numerous pathogens, and both their density and the pathogen prevalence determine the risk they pose to other animals or humans. However, density is often overlooked. We investigated a capture-mark-recapture-sampling strategy to study introduced mice (Mus musculus) and Leptospira as a model and demonstrate the advantages of a combined approach. We estimated population density and Leptospira prevalence in mice in a replicated longitudinal survey conducted between 2016 and 2018. Capture-mark-recapture sessions were undertaken at two sites in Spring and Autumn and blood and kidney samples were collected at the end of each session. Mouse density and areas of activity were estimated using spatially explicit capture–recapture (SECR) models and both were compared between Leptospira positive and negative mice. Leptospira exposure and shedding status were estimated using Microscopic Agglutination Test, and a combination of culture and lipL32 PCR on kidneys. Leptospira prevalence was higher in spring (83%–86%) than in autumn (31%–37%) and mouse densities simultaneously varied from 3.6 to 55.9/ha. However, despite these variations in prevalence and density, the density of infected animals remained relatively constant over time (3–8/ha). Shedding or being seropositive was also associated with the activity of mice. Shedding or seropositive mice had a larger activity area, and seropositive mice were trapped on average 1 day earlier than seronegative mice. Synthesis and applications: Our results show how understanding the population dynamics of pathogen-carrying rodents is critical in epidemiology. The wider movement patterns and easier encounters of positive mice highlight the possibility of biases in classical prevalence surveys and have implications for disease transmission within and between species. Importantly, and quite counter-intuitively, Leptospira prevalence was negatively associated with mouse density, resulting in a constant density of shedders that contradicts the conventional view of higher exposure risk at high rodent density. More broadly, such sampling designs can improve animal and disease control policies and better inform modelling studies by providing more parameter estimates than classical prevalence surveys.
Artigo
Habitat selection by Bothrops atrox (Serpentes: Viperidae) in central Amazonia, Brazil.
(Bioone, 2019-03-28) de Fraga, Rafael; Magnusson, William E.; Abrahão, Carlos R.; Sanaiotti, Tania; Lima, Albertina P.
Tropical rainforests often appear relatively homogeneous on satellite images, but responses to landscape characteristics may be found on finer scales if habitat characteristics are considered as continuous variables. In this study, we used 30 uniformly distributed plots and 16 plots beside streams to evaluate the effects of distance from stream, litter depth, altitude, slope, and tree density on abundance of Amazonian Lancehead Pitviper (Bothrops atrox). We estimated densities and probabilities of detection of snakes in riparian and upland plots in Reserva Ducke, Manaus, Amazonas,Brazil. Apparent density of individuals of B. atrox was about 6.4 times higher near streams, but the number of individuals in the landscape more than 10 m away from streams was about 3.9 times higher than the number of individuals within 10 m of streams. Movement data from two adult B. atrox evaluated by radio telemetry indicate that individuals can disperse out of plots and away from streams over a period of several months. Detectability of B. atrox varied little among riparian and upland plots, so differences in detectability are unlikely to be responsible for large differences in encounter rates of snakes between riparian and non-riparian areas. There were small differences in body size of individuals near streams and individuals far from streams. The distribution of B. atrox is not uniform within the forest. However, as with most other tropical-forest organisms studied to date, this species occurs across wide environmental gradients and shows only subtle habitat specificity.
Artigo
Population assessment of a novel island invasive: tegu (Salvator merianae) of Fernando de Noronha. In: C.R. Veitch, M.N. Clout, A.R. Martin, J.C. Russell and C.J. West (eds.) (2019). Island invasives
(Occasional Paper SSC no. 62. Gland, Switzerland: IUCN., 2019) Abrahão, Carlos R.; Russell, James Charles; Silva, Jean Carlos Ramos; Ferreira, F. E. Rodrigues; Dias, Ricardo Augusto
Fernando de Noronha is an oceanic archipelago in the Atlantic Ocean, 345 km o൵shore from the Brazilian coast. It comprises 21 islands and islets, of which the main island (FN) is 17 km2 with a rapidly growing tourism industry in the last decades. Despite being a protected area and bearing Ramsar and UNESCO World Heritage site status, it is threatened by multiple terrestrial invasive species since its colonisation in the early 16th century. Invasive species and the increasing tourism contributes to a list of at least 15 endangered or critically endangered species according to IUCN criteria. The black and white tegu (Salvator merianae) is the largest lizard in South America, occurring in most of the Brazilian territory and reaching up to 8 kg and 1.6 m from head to tail. As an omnivorous and opportunistic lizard, it feeds on a variety of available items, including smaller vertebrates and eggs. The introduction of the tegu to FN as well as its immediate impact on local fauna were not recorded; however, its ongoing impact is expected to be high. We captured and marked 103 tegu in FN during the months of February and November of 2015 and 2016. We also counted animals by line-transect census in a sparsely inhabited and an uninhabited area of FN. Body size a൵ected the capture probabilities, while season and sex had little or no e൵ect. Densities estimated by capture-recapture in the sparsely inhabited area varied from 2.29 to 8.28 animals/ha according to sampling season. Line transect census in the same area revealed a density of 3.98 (±1.1) animals/ha and in the uninhabited area 13.83 (±3.9) animals/ha. Home range was 10.54 ha, ranging from 7.36 to 15.33 hectares. Tegu activity decreased in the months of July and August of 2015. Results from this study can assist conservation managers and decision makers to implement a science-based tegu management programme in the future.
Artigo
Salmonella enterica in Invasive Lizard from Fernando de Noronha Archipelago:
(Microorganisms, 2017) Abrahão, Carlos R.; Moreno, Luisa Z.; Silva, Jean C. R.; Benites, Nilson R.; Matajira, Carlos E. C.; Ferreira, Fernando; Moreno, Andrea M.; Dias, Ricardo A.
Salmonella infection can pose serious health issues, especially to children, elders or immunosuppressed humans. Wild populations of reptiles can reach Salmonella prevalence of up to 100% and the direct or indirect transmission from reptiles to humans have been extensively reported. Fernando de Noronha (FN) is an inhabited oceanic archipelago in the northeast coast of Brazil, with an economy based on tourism. The tegu (Salvator merianae) is the largest lizard native to South America and was introduced to the archipelago in the early 20th century. This study determines the prevalence, serotypes, antimicrobial resistance, and molecular epidemiology of Salmonella enterica in the tegu population from FN archipelago. Results show that S. enterica is widely distributed in the FN tegu population, with 43.8% prevalence. The bacteria were isolated from 70.5% of the sampled sites and a total of 15 serotypes were detected in 98 S. enterica isolates. Strains were further classified into 31 genotypes. Recaptured animals presented distinct genotypes in each season, demonstrating a seasonal strain turnover. Most S. enterica isolates from FN tegus presented low antimicrobial resistance. This is possibly due to geographical isolation of the island population, hampering contact with strains from livestock from the continent, where antimicrobial resistance is common.
Artigo
Using genetics to plan black rat (Rattus rattus) management in Fernando de Noronha archipelago, Brazil.
(Perspectives in Ecology and Conservation, 2020) Gatto-Almeida, Fernanda; Pichlmueller, Florian; Micheletti, Tatiane; Abrahão, Carlos R.; Mangini, Paulo R.
Invasive mammals such as rats are associated with negative impacts on native fauna and their eradication on islands around the world has been proved to result in substantial conservation gains. Fernando de Noronha is an archipelago located off the north-east coast of Brazil and has records of native fauna negatively impacted by introduced rats. We used D-Loop sequences and 14 microsatellite markers to investigate gene flow between three populations of Rattus rattus across two islands of Fernando de Noronha. Using both methods we found very great differentiation between the two islands, indicating very low or no gene flow. Our findings suggested if Rata Island were cleared of rats it would have a low probability of reinvasion occurring from the main island. Thus, we recommend an eradication program be implemented on Rata Island following the successful program on nearby Meio Island. © 2020 Associac¸ ao˜ Brasileira de Ciencia ˆ Ecologica ´ e Conservac¸ ao. ˜ Published by Elsevier Editora Ltda. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/).