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Ciudad Real, Spain

Nugent G.,Landcare Research | Gortazar C.,SaBio IREC UCLM CSIC JCCM | Knowles G.,TBfree New Zealand
New Zealand Veterinary Journal | Year: 2015

Abstract: In New Zealand, wild deer and feral pigs are assumed to be spillover hosts for Mycobacterium bovis, and so are not targeted in efforts aimed at locally eradicating bovine tuberculosis (TB) from possums (Trichosurus vulpecula), the main wildlife host. Here we review the epidemiology of TB in deer and pigs, and assess whether New Zealand's TB management programme could be undermined if these species sometimes achieve maintenance host status. In New Zealand, TB prevalences of up to 47% have been recorded in wild deer sympatric with tuberculous possums. Patterns of lesion distribution, age-specific prevalences and behavioural observations suggest that deer become infected mainly through exposure to dead or moribund possums. TB can progress rapidly in some deer (<10%), but generalised disease is uncommon in wild deer; conversely some infected animals can survive for many years. Deer-to-deer transmission of M. bovis is rare, but transmission from tuberculous deer carcasses to scavengers, including possums, is likely. That creates a small spillback risk that could persist for a decade after transmission of new infection to wild deer has been halted. Tuberculosis prevalence in New Zealand feral pigs can reach 100%. Infections in lymph nodes of the head and alimentary tract predominate, indicating that TB is mostly acquired through scavenging tuberculous carrion, particularly possums. Infection is usually well contained, and transmission between pigs is rare. Large reductions in local possum density result in gradual declines (over 10 years) in TB prevalence among sympatric wild deer, and faster declines in feral pigs. Elimination of TB from possums (and livestock) therefore results in eventual disappearance of TB from feral pigs and wild deer. However, the risk of spillback infection from deer to possums substantially extends the time needed to locally eradicate TB from all wildlife (compared to that which would be required to eradicate disease from possums alone), while dispersal or translocation of pigs (e.g. by hunters) creates a risk of long-distance spread of disease. The high rate at which pigs acquire M. bovis infection from dead possums makes them useful as sentinels for detecting TB in wildlife. It is unlikely that wild deer and feral pigs act as maintenance hosts anywhere in New Zealand, because unrestricted year-round hunting keeps densities low, with far less aggregation than on New Zealand farms. We conclude that active management of wild deer or feral pigs is not required for local TB eradication in New Zealand. © 2015 Landcare Research. Published by Taylor & Francis. Source

Segura A.,University of Oviedo | Acevedo P.,University of Porto | Rodriguez O.,SaBio IREC UCLM CSIC JCCM | Naves J.,CSIC - Donana Biological Station | Obeso J.R.,University of Oviedo
European Journal of Wildlife Research | Year: 2014

The population dynamics of wild ungulates, particularly wild boar (Sus scrofa), are modulated by biotic (e.g. predation) and abiotic (environmental) determinants. Despite the evident potential interference of predation in the environmental patterns of wild boar population abundance, studies including both predation and abiotic factors are scarce. Here, using spatially explicit predictive models, we investigated the effects of habitat features on the relative abundance of wild boar populations and how the abundance of boars is related to frequency of Iberian wolf (Canis lupus signatus; hereafter, wolf) in the area. Wild boar relative abundance was determined by hunting bag statistics, including hunting effort-related variables (in order to avoid problems derived from modeling rates) as covariates, while wolf attacks to livestock were considered as a proxy of wolf frequency in the drive. After modeling, variation partitioning procedures were used to determine the relative importance of each factor and their overlaid effects. Our results showed that wild boar and wolf relative abundances are associated. According to previous knowledge on the wild boar ecology, we found that the species abundance is positively related to the percentage of surface occupied by mature forest and heather providing high food diversity and refuge, but these environmental variables achieved a low explanatory capacity in the models in relation to wolf frequency. The holistic approach followed in this study was attended to open new perspectives for thinking on the wolf-livestock conflict and to adequate wild boar management strategies taking into account hunting interests and natural processes. © 2014 Springer-Verlag Berlin Heidelberg. Source

Acevedo P.,University of Porto | Acevedo P.,Autonomous University of Barcelona | Quiros-Fernandez F.,SaBio IREC UCLM CSIC JCCM | Casal J.,Autonomous University of Barcelona | Vicente J.,SaBio IREC UCLM CSIC JCCM
Ecological Indicators | Year: 2014

The Eurasian wild boar (Sus scrofa) is growing in numbers and has been expanding its distribution in Europe from some decades ago. This increasing trend, in some circumstances, leads to conflicts involving several sectors, among others, agriculture damages, conservation problems and health risks. The disease-related conflicts are especially relevant; wild boar was raised as a potential host for numerous pathogens provoking economic losses to the livestock industry. In a wildlife management context, reliable indicators of wild boar abundance at large spatial scales are highly demanded. Thus, our main aim was to handle hunting bag data available for the 2006-2007 to 2009-2010 hunting seasons in order to develop a predictive model able to account for wild boar abundance in overall mainland Spain. For modelling, the response variable was the number of wild boars annually hunted per 100 km2 in each hunting estate, as a well-established wild boar abundance index. Using data for 6280 hunting estates (∼44% of the study area), and 21 ecogeographical predictors (geography, climate and land cover), we modelled the species abundance by means of generalized linear models with a negative binomial distribution. Three analytical approaches were comparatively assessed, which differed in how the five bioregions considered in the Spanish Wildlife Disease Surveillance Scheme were considered in modelling. In terms of predictive performance on independent datasets, the approach in which five independent models were adjusted (one per bioregion) achieved the highest scores. These models were used to predict wild boar abundance in overall mainland Spain by using UTM 10 × 10 km squares (n = 5245) and municipalities (n = 8050) as territorial units, in order to enhance the representativeness of the model at national scale and their usefulness in epidemiological studies, respectively. The pattern for wild boar abundance obtained in this study enlarges the knowledge of this species in mainland Spain. The analytical procedure developed here is valuable in itself, and it can be considered to model the spatial patterns of wild boar - or other relevant species - elsewhere, which is information highly demanded for wildlife managers in general and epidemiologists in particular. © 2013 Elsevier Ltd. Source

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