Distribution and risk factors of the seroprevalence of Lawsonia intracellularis

Based on 6,500 blood samples from 126 pig farms the prevalence of Lawsonia intracellularis infections in Germany was investigated in comparison to the serological results from other European countries. Furthermore, data from an epidemiological questionnaire completed at the same time the pigs were bled was analysed to show the influence of production parameters on the serological profiles. As early as 10 weeks of age, 44 % of the tested farms were classified as Lawsonia intracellularis positive. Weaning to mid-period fattening pigs in farms located in the south of Germany showed significantly greater antibody levels than pigs in eastern German farms. These results clearly support that pigs in the South of Germany become infected shortly after weaning. Seroconversion patterns among pigs from all European countries revealed that Danish pigs show significantly greater antibody levels in all tested age groups. Farm size and production systems were identified to have a significant influence on the antibody titres. Pigs with a good feed conversion ratio below 2.75 had significant lower antibody titre values than pigs with a feed conversion ratio above 2.75. Independent of the analysed parameter there were no significant differences seen in the antibody titre values of slaughter pigs. It is only a question of time and not of influencing parameters until all pigs in a Lawsonia-positive farm are actively infected with Lawsonia intracellularis.