Background

Bovine tuberculosis (bTB) is a chronic infectious disease mainly caused by Mycobacterium bovis. Although eradication is a priority for the European authorities, bTB remains active or even increasing in many countries, causing significant economic losses. The integral consideration of epidemiological factors is crucial to more cost-effectively allocate control measures. The aim of this study was to identify the nature and extent of the association between TB distribution and a list of potential risk factors regarding cattle, wild ungulates and environmental aspects in Ciudad Real, a Spanish province with one of the highest TB herd prevalences.

Results

We used a Bayesian mixed effects multivariable logistic regression model to predict TB occurrence in either domestic or wild mammals per municipality in 2007 by using information from the previous year. The municipal TB distribution and endemicity was clustered in the western part of the region and clearly overlapped with the explanatory variables identified in the final model: (1) incident cattle farms, (2) number of years of veterinary inspection of big game hunting events, (3) prevalence in wild boar, (4) number of sampled cattle, (5) persistent bTB-infected cattle farms, (6) prevalence in red deer, (7) proportion of beef farms, and (8) farms devoted to bullfighting cattle.

Conclusions

The combination of these eight variables in the final model highlights the importance of the persistence of the infection in the hosts, surveillance efforts and some cattle management choices in the circulation of M. bovis in the region. The spatial distribution of these variables, together with particular Mediterranean features that favour the wildlife-livestock interface may explain the M. bovis persistence in this region. Sanitary authorities should allocate efforts towards specific areas and epidemiological situations where the wildlife-livestock interface seems to critically hamper the definitive bTB eradication success.

Background

The goal of this study was describing the temporal evolution of Aujeszky's disease virus (ADV) contact prevalence among Eurasian wild boar (Sus scrofa) populations under different management regimes and contact likelihoods with domestic pigs. Given the recent increase in wild boar abundance throughout Europe, we hypothesized that wild boar contact with ADV would remain stable in time even after significant reduction of ADV prevalence in domestic pigs.

Results

Sera from 1659 wild boar were collected from 2000 to 2010 within 6 areas of the Iberian Peninsula and tested for the presence of antibodies against ADV by ELISA. According to sampling date, wild boar were grouped into three time periods. ADV prevalence was compared through period both globally and by geographic area. Overall seroprevalence for the ten-year study period was 49.6 ± 2.4%. The highest seroprevalence was recorded in areas with intense wild boar management. The annual proportion of positive wild boar sampling sites remained stable through the study period, while the percentage of domestic pig AD positive counties decreased from 70% in 2003 to 1.7% in 2010.

Conclusions

Results presented herein confirmed our hypothesis that ADV would remain almost stable in wild boar populations. This evidences the increasing risk wild boar pose in the final stages of ADV eradication in pigs and for wildlife conservation.

Background

The roe deer is the most abundant and widespread wild Eurasian cervid. Its populations are expanding and increasingly in contact with livestock. This may affect the distribution of infectious diseases shared with other wild and domestic ungulates.

Methods

We investigated the antibody seroprevalence against Pestivirus, Herpesvirus, Bluetongue (BT) virus, M. avium paratuberculosis (MAP), and Brucella sp. in 519 roe deer from different regions in Spain, south-western Europe.

Results

No antibodies were detected against BT and Brucella sp. However, antibodies were detected against Pestivirus (1.5%), Herpesvirus (0.2%) and MAP (9.2%). MAP antibodies were detected in seven of the eight populations (range 5-16.4%).

Conclusions

The detection of MAP antibodies in samples from most roe deer populations suggests that contact with MAP is widespread in this wildlife species. The highest prevalence was detected in sites with abundant dairy cattle and frequent use of liquid manure on pastures. Considering the results obtained regarding exposure to different pathogens, we suggest that antibody prevalences in this non-gregarious browser are largely determined by environmental factors, potentially modulating vector populations or pathogen survival in the environment.

Background

Bovine tuberculosis (bTB) remains a significant problem in some parts of Spain largely because of contacts between cattle and wildlife reservoirs in extensive grazing systems. European Wild boar (Sus scrofa) is one of the species involved in the transmission of the disease to other species. Fast and simple detection methods would be critical for assessing infection prevalence, study the mechanisms of pathogen transmission and monitoring the effects of TB control measures.

Results

An enzyme-linked immunosorbent assay (ELISA) to detect antibodies against Mycobacterium bovis in wild boar serum was developed and validated on 185 sera from TB positive and negative wild boar. Based on antigen inoculation of captive animals as well as tuberculosis compatible lesions, culture results and molecular analysis of hunted individuals, animals were allocated into two groups: tuberculosis positive group and tuberculosis negative group. After optimization of the positive to negative ratio using different combinations of serum dilutions and conjugate concentrations, the test yielded a sensitivity of 72.60% and a specificity of 96.43% for the best cut-off.

Conclusion

Although some negative group animals showed an ELISA positive reaction (< 3%), this assay showed a high potential for accurate diagnosis of TB in wild boar, as its large dynamic range supported a good discriminatory power and a satisfactory balance between sensitivity and specificity.