SCOTLAND - Results from a recent survey indicate that more than 60 per cent of slaughter pigs suffer some degree of Ileitis during their lives. The findings, collected from a comprehensive blood-testing programme carried out in Scotland, provides valuable information on the disease and how control methods could be improved.
Quality Meat Scotland, in collaboration with Boehringer Ingelheim, completed the large scale surveillance programme for the production-limiting disease, porcine ileitis or porcine proliferative enteropathy (PPE).
Blood samples from six slaughter pigs from each of 157 units belonging to the 'Wholesome Pigs Scotland' (WPS) abattoir monitoring scheme were tested. These farms represent over 90 per cent of Scottish pig herds.
The study found that:
- 68 per cent of all the pigs sampled from the 157 units (641/942) had antibodies to L. intracellularis indicating that they had been infected at some time in the growing period.
- 90 per cent of herds sampled had at least one positive sample out of the 6 tested. (Statistically this level of sampling is only capable of detecting a "positive herd" if the number of infected animals is above a certain threshold. Some farms with no positive samples may still therefore have Lawsonia infection making the true herd prevalence even higher than 90 per cent)
- Most herds had more than four out of six pigs giving positive results.
Ileitis is known to have a worldwide distribution. Previous surveys have determined a high prevalence of the infection in the UK pig herd but this is the first time such a detailed census has been performed in the UK. This study not only gives an overview of the overall prevalence in the Scottish national herd but also gives all WPS member producers knowledge of the ileitis status of their own individual farms. This should allow producers and their veterinary surgeons to make more informed decisions on further disease investigation and control strategies, including the use of Enterisol® Ileitis vaccine.
Guidance Needed
Although this type of survey provides valuable information about the prevalence of the disease, it gives no clear guidance as to the impact of the infection on the individual herds assessed.
It is likely however that many of these units are suffering from some degree of clinical disease.
A survey of 319 pig farms in England and Scotland conducted in 1998 suggested that 31 per cent of farms had experienced one or more clinical outbreaks of disease in the previous 3 years (Smith et al., 1998) and that the picture is unlikely to be very different today, even with the complicating effects of post-weaning multisystemic wasting syndrome (PMWS). It is also estimated that up to 30 per cent of infected herds may also be sub-clinically affected in that although there are no obvious signs of disease, deleterious effects on growth rate and feed conversion efficiency are present.
The results obtained in this study broadly agree with those of a UK and Eire survey carried out in 2000 which estimated a 62% of pigs tested had been infected and around 95 per cent of herds housed infected pigs (Mortimer et al., 2000).
References
Mortimer, I., Green, L. and Hodge, A. (2000) Serological prevalence of Lawsonia intracellularis across UK and Irish pig herds. In Proc. Int. Congr. Pig Vet. Soc. 16:110
Smith, S.H., McOrist, S. and Green, L.E. (1998) Questionnaire survey of proliferative enteropathy on British pig farms. Vet. Rec. 190: 690-693