BPEX Pig Health Scheme: a useful monitoring system for respiratory disease control in pig farms?

<p>Abstract</p> <p>Background</p> <p>Respiratory diseases account for significant economic losses to the UK pig industry. Lesions indicative of respiratory disease in pig lungs at slaughter e.g. pneumonia and pleuritis are frequently recorded to assess herd health or provide data for epidemiological studies. The BPEX Pig Health Scheme (BPHS) is a monitoring system, which informs producers of gross lesions in their pigs' carcasses at slaughter, enabling farm-level decisions to be made. The aim of the study was to assess whether information provided by the BPHS regarding respiratory lesions was associated with respiratory pathogens in the farm, farm management practices and each other.</p> <p>Results</p> <p>BPHS reports were obtained from a subset of 70 pig farms involved in a cross-sectional study conducted in 2008-09 investigating the epidemiology of post-weaning multi-systemic wasting syndrome. The reports were combined with data regarding the presence/absence of several pathogens in the herd and potential farm-level risk factors for respiratory disease. Principal component analysis (PCA) performed on BPHS reports generated three principal components, explaining 71% of the total variance. Enzootic pneumonia score, severe pleurisy and acute pleuropneumonia had the highest loadings for the principal component which explained the largest percentage of the total variance (35%) (BPHS component 1), it was thought that this component identifies farms with acute disease. Using the factor loadings a score for each farm for BPHS component 1 was obtained. As farms' score for BPHS component 1 increased, average carcass weight at slaughter decreased. In addition, farms positive for H1N2 and porcine reproductive and respiratory disease virus (PRRSV) were more likely to have higher levels of severe and mild pleurisy reported by the BPHS, respectively.</p> <p>Conclusions</p> <p>The study found statistical associations between levels of pleurisy recorded by BPHS at slaughter and the presence H1N2 and PRRSV in the herd. There is also some evidence that farms which submit pigs with these lesions may have reduced productivity. However, more research is needed to fully validate the scheme.</p

Herd-level prevalence of selected endemic infectious diseases of dairy cows in Great Britain

To implement appropriate and effective disease control programs at national level, up-to-date and unbiased information on disease frequency is needed. The aim of this study was to estimate the prevalence of selected endemic infectious diseases in the population of dairy herds in Great Britain. Bulk milk tank (BMT) samples from 225 randomly selected dairy farms stratified by region and herd size were tested for antibodies against bovine viral diarrhoea virus (BVDV), bovine herpesvirus type 1 (BHV-1), Mycobacterium avium subspecies paratuberculosis (MAP), Leptospira hardjo , Salmonella spp., Coxiella burnetii , Fasciola hepatica , Neospora caninum , and Ostertagia ostertagi . Furthermore, the presence of BVDV, C. burnetii and Chlamydia-like organisms was determined by polymerase chain reaction (PCR). The apparent herd prevalence was estimated as a weighted proportion of positive herds. The true prevalence was calculated when a test was used with known test characteristics for the cut-off value used. Amongst unvaccinated herds, the true prevalence ofBMT antibodies against BVDV was estimated at 66% (95% Confidence 47 Interval, CI: 56-77%), MAP 68% (95% CI: 59-77%), BHV-1 62% (95% CI: 52-73%), L. hardjo 47% (95% CI: 34-60%) and Salmonella spp. 48% (95% CI: 39-56%). The apparent prevalence of BMT antibodies against C. burnetii was 80% (95% CI: 75-85%), F. hepatica 55% (95% CI: 48- 62%), N. caninum 46% (95% CI: 38-54%), and O. ostertagi 95% (95% CI: 91-98%). BVDV, C. burnetii and Chlamydia-like antigens were detected in 5% (95% CI: 2-9%), 29% (95% CI: 21-36%) and 31% (95% CI: 24-38%) of herds, respectively. Our results show that dairy cows across GB are frequently exposed to the studied pathogens, which are endemic at high levels with some geographical variations. These prevalence estimates provide a much needed basis to assess whether nationwide control programs for the studied pathogens are justified by their potential economic, environmental and public health implications. Should surveillance and control programs be initiated, the estimates presented here are a baseline against which progress can be assessed