Post-weaning Multisystemic Wasting Syndrome (PMWS)
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Introduction to PMWS Postweaning multisystemic wasting syndrome (PMWS) is a pig disease affecting pigs aged 6- 16 weeks. It is characterised by wasting, pale, hairy pigs with enlarged lymph nodes, scouring (diarrhoea) and often dyspnoea (respiratory distress). PMWS in a herd is characterised by a significant and prolonged increase in mortality that eventually declines but only to a level that remains significantly above that observed before the outbreak. PMWS has a morbidity rate of approximately 5-20% of pigs in the affected age range and a mortality of 80% of affected pigs. To put this into context, it has been reported that on a farm PMWS can increase the postweaning mortality from 1-2% to 10-25%. This increase in mortality would represent significant financial losses. Since entering England in 1999, PMWS has spread throughout the UK, reaching Scotland in 2002 (Woodbine et al, In Press) Currently BPEX estimates that approx 6000 units in the UK were affected with PMWS in 2006, and an estimated 83% of British pig units were affected in March 2007. The Warwick Cross- sectional study The Warwick PMWS project was a study of 114 UK pig farms visited between June 2003 and August 2004. Data was collected by both a pre-visit self administered and an interview style questionnaire to the farmer and vet and by observation of the conditions of the buildings and pens occupied by the pigs. Blood samples of
were collected from each farm and tested for antibodies against Porcine Circovirus type 2 (PCV2), Porcine parvovirus (PPV) and Porcine Reproductive & Respiratory Syndrome (PRRS) virus. 1 healthy pig and up to 3 sick pigs were also taken from each farm for post-mortem examination and histology. Their lymph nodes were tested for PCV2 antigen. Results The first results from this study can be viewed in the Farmers' section of this website. Preliminary findings from part of the study were presented in 3 posters at the Annual Meeting of the Society for Veterinary Epidemiology and Preventive Medicine, 2005. Brief summary of results
A cohort study on PMWS A cohort study was carried out on a farm which had just broken down wth PMWS. This farm was previously recruited into the cross-sectional study of factors associated with PMWS and had a negative PMWS status at this time The farm reported a breakdown with PMWS in March 2004 and at consequently was re-visited to obtain another PCV2 serological profile. It was then recruited for this study and visited 2-3 days a week between July 2004 and March 2005 The study farm was a multiplier unit, producing female breeding pigs (gilts) for sale to commercial pig units, in order to minimise the risk of economic losses to the farm, only male piglets were recruited for the current study. Litters were selected with preference to litters from sows that had been sampled in the cross- sectional study visit, and those that were sampled in the second visit. A total of 200 piglets from 36 litters were enrolled to the study and upon enrolment the pigs were ear tagged. All the pigs, aged 0-16 weeks, on the farm that died during the study period were taken for post mortem examination (PME) to Leeds Veterinary Laboratory (LVL). The inguinal, trachobronchial and ileocaecocolic lymph nodes were removed and half of each was submitted for histological examination and the other half was used to determine the PCV2 antigen concentrations. Results
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   MLC/BPEX   People involved: We are grateful to: |
