The prevalence of Lawsonia intracellularis in swine herds in Poland

Proliferate enteropathy (PE) is an enteric disease that occurs primarily in weaning and fattening pigs. Various publications have noted that the perce ntage of infected herds in agriculturally developed countries is as high as 30-50%. The disease is widespread in swine and results mainly in growth-ra te losses and increased feed efficiency. The aim of the study was to perform an epidemiological survey on Polish pig farms in order to discover the prevalence of herds infected with L. intrac ellularis. Biological material for laboratory investigations was collected from 54 pig farms (36 farrow-to-finish, 8 breeding and 10 fattening herds). A number of pigs in all the farms surveyed showed clinical symptoms charac teristic for PE. The size of the herds differed, with the smallest herd hav ing 10 and the biggest 2,540 sows. The number of pigs in fattening farms al so varied. The smallest had an annual production of 2500 fatteners and the largest - 23 000 animals. Biosecurity measures were disregarded,: and "all in all out" procedures were not applied. Weaning time differed throughout t he farms and varied between 24-42 days. Faecal samples were taken directly from each animal and kept in refrigerate d storage for further examinations. The sampled pigs were selected amongst those showing possible signs of the disease (poor growth, diarrhoea). A tot al of 957 faecal samples were collected to find the genetic material of L. intracellularis. Total DNA was extracted from the faeces which had been tak en from the weaned piglets and fatteners having diarrhoea by using the Geno mic DNA Prep Plus (R) kit (Helicionus, A&A Biotechnology). Five micro liter s of DNA were amplified by one tube nested - PCR technique, using two sets of PCR primers, which consisted of 20 - base pair (bp) oligonucleotides cor responding to 319 bp and 270 bp regions of p78 L. intracellularis sequence. The results indicated that 10 fattening farms were infected with L. intrace llularis. Herds in 7 out the 8 breeding farms 7 (87,5%) were susceptible to infection. 23 (63,8%) out of a total of 36 farrow-to-finish farms were fou nd to be positive. Small farms, which counted less then 50 sows, were negat ive for L. intracellularis. The highest percentage of positive faecal sampl es (84,2%) was found in fattening farms. An average of 30,8 % of pigs were infected in farrow-to-finish farms. The lowest percentage of infected anima ls was noted in nucleus herds (19,7%). Adding growth promoters to the feed did not significantly influence the pre sence of the infections in the farms. No evidence of the acute form of ilei tis (Porcine haemorrhage enteropathy - PHE) was found to be present or conf irmed in any of the investigated farms. Most PE-infected herds in Poland re vealed a chronic form of the disease. An epidemiological study showed that distribution of L. intracellularis inf ections is widespread within populations of Polish swine herds.