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We have focused on the role played by a carnivore, the coati (Nasua nasua), in the transmission cycle of Trypanosoma cruzi in the Brazilian Pantanal biome. We collected data during 2000/01 and 2005-07. Prevalence and pattern of T. cruzi infection were determined by serological tests and hemoculture. Isolates were characterized by miniexon molecular assay. Our results demonstrate that T. cruzi transmission cycle among coatis in the southern Pantanal seems to be well established, as we found high serum prevalences and high parasitemias throughout the two studied periods. Single infections by TCII (32.1%), TCI (28.0%) and Z3 (7.1%) were observed. Mixed infections by TCI/TCII (10.7%) and TCI/Z3 (3.6%) were also detected. Distinct genotypes of T. cruzi could be recovered during the 8 months follow-up of the same animals. As free-living coatis have high densities and inhabit all habitats, they may play an important role in the maintenance and dispersion of the main T. cruzi subpopulations. Considering that the Pantanal connects some of the major biomes of South America, it may be acting as a corridor for the spread of the main T. cruzi subpopulations. Our data give support that predator-prey links are important mechanisms for T. cruzi transmission and perpetuation in the wild.

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Anthropic activities are frequently related in many ways to forest fragmentation and alteration of natural communities. In this study, we correlate the presence of hunting, tourism activity, agriculture/pasturing, and the distance of the study sites to the nearest human residences with the species composition of small Atlantic forest mammals. To do this, we utilize a multiple regression analysis of similarity matrices. The presence of both agriculture/pasturing and human residences near the study sites proved to be determinant factors in species composition of small mammals of the studied areas. Working with socioeconomic variables related directly with the study site could be a reliable and a direct way to predict the influence of human presence and entailed activity on small mammal communities.

Conservation and management of animal populations often require knowledge about the age structure, but this information is usually difficult to discern. We propose a method to estimate the age of carnivores based on dental condition and body size measurements, and we apply the method to populations of brown‐nosed coatis Nasua nasua and crab‐eating foxes Cerdocyon thous in the Brazilian Pantanal. We sexed, weighed and measured 31 coatis and 45 foxes of known‐age, and characterized and quantified their pattern of dental eruption and wear for the construction of a teeth condition index. Scores of the first factors of a principal component analysis including data on six body size measurements and the teeth condition index of the individuals were then used in a discriminant analysis to generate functions that can be used for estimating age of animals of unknown age. Models were validated using subsets of individuals of known age through a 3‐fold cross validation process. The first functions accounted for over 90% of the discriminatory power for both species. Whereas in coatis, the first function was mainly explained by the body size measurements, in crab‐eating foxes it was represented mainly by the teeth condition index. During model validation, individuals were on average classified with 88 and 80% average confidence for coatis and foxes, respectively. Our method is as accurate as other methods that are commonly applied to assess age, but less subjective. While it requires animal capturing, it is less invasive than methods requiring tissue removal such as analyses of teeth cementum annuli. The method we outlined can be used for age estimation of other populations, as long as the models are validated with a subset of animals from the region studied. It could also be useful as a model for estimating age of other carnivore species.

Background: The nematode Angiostrongylus cantonensis is a zoonotic parasite and the most important cause of eosinophilic meningitis worldwide in humans. In Brazil, this disease has been reported in the states of Espírito Santo and Pernambuco. The parasite has been detected in the naturally infected intermediate host, in the states of Rio de Janeiro, Pernambuco and Santa Catarina. The murid Rattus norvegicus R. rattus were recently reported to be naturally infected in Brazil. In this study, we conducted a two-year investigation of the dissemination pattern of A. cantonensis in R. norvegicus in an urban area of Rio de Janeiro state, Brazil, and examined the influence of seasonality, year, host weight and host gender on parasitological parameters of A. cantonensis in rats. Methods: The study was conducted in an area of Trindade, São Gonçalo municipality, Rio de Janeiro, Brazil. Prevalence of infected rats, intensity and abundance of A. cantonensis were calculated, and generalized linear models were created and compared to verify the contribution of host gender, host weight, year and seasonality to the variations in A. cantonensis abundance and prevalence in rats. Results:The prevalence of A. cantonensis infection was stable during the rainy (71%, CI 58.9-81.6) and dry seasons (71%, CI 57.9-80.8) and was higher in older rats and in females. Seasonality, host weight (used as a proxy of animal age) and gender were all contributing factors to variation in parasite abundance, with females and heavier (older) animals showing larger abundance of parasites, and extreme values of parasite abundance being more frequent in the dry season. Conclusions: The high prevalence of this parasite throughout the study suggests that its transmission is stable and that conditions are adequate for the spread of the parasite to previously unaffected areas. Dispersion of the parasite to new areas may be mediated by males that tend to have larger dispersal ability, while females may be more important for maintaining the parasite on a local scale due to their higher prevalence and abundance of infection. A multidisciplinary approach considering the ecological distribution of the rats and intermediate hosts, as well as environmental features is required to further understand the dynamics of angiostrongyliasis.

This is a long-term follow-up of infection by Trypanosoma cruzi (TC) and Trypanosoma evansi (TE) in the free-ranging coatis (Procyonidae: Nasua nasua) from Pantanal region (Mato Grosso do Sul, Brazil). We evaluated TC and TE infection by immunofluorescence assay, hemoculture (HC), and microhematocrit centrifuge techniques (MHCT). We also examined coatis health by quantifying hematological parameters including packed cell volume (PCV), white blood cell (WBC) count, and differential leukocyte count. TC isolates thought HC were typed by miniexon gene. Mixed infections by both parasites and the two main lineages of TC (76% TCI, 3% TCII, and 14% TCI/TCII) were observed. Trypanosoma rangeli was also isolated (7%). Overall, seroprevalence of TC and TE infection were 53.5% and 42.0%, respectively. Positive HC (indicating high TC parasitemia) occurred in 34% of seropositive coatis for TC, and positive MHCT (high TE parasitemia) were observed in 36.4% of seropositive coatis for TE. We detected higher prevalence of positive HC in females (72%) than males (43%), and also during the dry season, indicating a seasonal potential of this host species on TC transmission. These features did not occur for TE infection. However, prevalence of TE based on serology and MHCT was higher among adults than subadults. Coatis with positive HC or MHCT displayed a slight decrease in their WBC. In contrast to the animals with positive HC, coatis with positive MHCT displayed a decrease on their PCV. Moreover, concurrent high TC and TE parasitemia caused a larger decrease of PCV values. This study corroborates the importance of coatis in the maintenance of TC and TE transmission cycles in the southern Pantanal and shows a seasonal character of TC transmissibility to its vector by the coati population from the study area.